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RESEARCH ARTICLE
Health, environmental, and animal rights
motives for vegetarian eating
Christopher J. HopwoodID*, Wiebke Bleidorn, Ted Schwaba, Sophia Chen
University of California, Davis, CA, United States America
Abstract
Health, the environment, and animal rights represent the three main reasons people cite for
vegetarian diet in Western societies. However, it has not been shown that these motives can
be distinguished empirically, and little is known about what kind of people are likely to be com-
pelled by these different motives. This study had three goals. First, we aimed to use construct
validation to test whether develop health, environmental, and animal rights motives for a veg-
etarian diet could be distinguished. Second, we evaluated whether these motivations were
associated with different demographic, behavioral, and personality profiles in three diverse
samples. Third, we examined whether peoples’ motivations were related to responses to veg-
etarian advocacy materials. We created the Vegetarian Eating Motives Inventory, a 15-item
measure whose structure was invariant across three samples (N = 1006, 1004, 5478) and
two languages (English and Dutch). Using this measure, we found that health was the most
common motive for non-vegetarians to consider vegetarian diets and it had the broadest
array of correlates, which primarily involved communal and agentic values. Correlates of
environmental and animal rights motives were limited, but these motives were strong and
specific predictors of advocacy materials in a fourth sample (N = 739). These results provide
researchers with a useful tool for identifying vegetarian motives among both vegetarian and
non-vegetarian respondents, offer useful insights into the nomological net of vegetarian moti-
vations, and provide advocates with guidance about how to best target campaigns promoting
a vegetarian diet.
Eating is an important day to day behavior at the interface of individual differences, social
dynamics, economics, health, and ethics. Vegetarianism has emerged as a significant dietary
movement in Western cultures [1–3]. The benefits of vegetarian diets include improved indi-
vidual health [4–8], a more sustainable environment [4,9–11], and a more humane approach
to inter-species relationships [12–19].
Health, environment, and animal rights also appear to represent the primary non-religious
motives for a plant-based diet [1,20–24]. However, thus far there is very little evidence that
these motives can be distinguished empirically, and no existing measures of eating behavior is
available to measure health, environment, and animal rights as distinct motives for vegetarian
diet. One consequence of this gap in the literature is that relatively little is known about the
PLOS ONE
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 1 / 20
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OPEN ACCESS
Citation: Hopwood CJ, Bleidorn W, Schwaba T,
Chen S (2020) Health, environmental, and animal
rights motives for vegetarian eating. PLoS ONE
15(4): e0230609. https://doi.org/10.1371/journal.
pone.0230609
Editor: Valerio Capraro, Middlesex University,
UNITED KINGDOM
Received: December 18, 2019
Accepted: March 3, 2020
Published: April 2, 2020
Peer Review History: PLOS recognizes the
benefits of transparency in the peer review
process; therefore, we enable the publication of
all of the content of peer review and author
responses alongside final, published articles. The
editorial history of this article is available here:
https://doi.org/10.1371/journal.pone.0230609
Copyright: © 2020 Hopwood et al. This is an open access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: Pre-registration,
methods, measures, scripts, and supplemental
results for samples 1-3 as well as data for samples
1 and 2 are available at https://osf.io/52v6z/. Data
for sample 3 cannot be shared publicly because it
psychological implications of these different reasons for a vegetarian diet. Initial research sug-
gests that extraverted and sociable individuals tend to be more motivated by health [25,26]
whereas factors such as agreeableness, openness, altruism, and empathy may be more related
to ethical motivations [27,28]. However, findings are often inconsistent, and a wide range of
potentially important correlates have not been examined. Understanding these motives is
important for advancing knowledge about this increasingly important behavior, and it may
also have practical value in the area of advocacy.
Advocates for plant-based diets typically focus on at least one of these three motives when
trying to convince people to adopt a plant-based diet or join a vegan organization [20,29–31].
Advocacy campaigns may be more effective to the degree that they target the specific motives
of different groups and individuals [30,32] because people are more likely to respond to mes-
sages that target their personal needs and interests [33]. Moreover, focusing on issues that do
not resonate with individuals’ motives may negatively impact animal advocacy, such as when
the exposure to animal rights advocacy creates an unpleasant emotional reaction [34] that
worsens opinions of vegetarians and animal advocacy [31]. Thus, it is in the interest of advo-
cacy groups to better understand the kinds of people who are more or less likely to respond to
activism that emphasizes health, the environment, or animal rights. From an advocacy per-
spective, it is particularly important to understand the motives to which non-vegetarians are
most sympathetic, given that these are the individuals that are targeted by advocacy
campaigns.
The goals of this research were to 1) evaluate the structure of common motives for a vege-
tarian diet, 2) to use that measure to develop behavioral and psychological profiles of people
who would be most likely to adopt a plant-based diet for different reasons, and 3) examine
whether this profile predicts responses to advocacy materials.
Motives for a plant-based diet
Many instruments have been developed to assess diet-related motives. Early work tended to
focus on specific motives of interest for a particular research topic. For example, Jackson,
Cooper, Mintz, and Albino [35] created a scale focused on eating motives in the context of sub-
stance abuse, which included four dimensions: coping, social motives, compliance, and plea-
sure. While this instrument outlines a useful model of psychological eating motives, it is less
suitable for research on vegetarian diet because any of these four motives could lead a person
to eat either vegetarian or non-vegetarian food, depending on other considerations.
Several instruments tap eating motives that are more likely to distinguish vegetarian from
non-vegetarian eaters. The Food Choice Questionnaire (FCQ; [36]) focuses on nine motives: convenience, price, health, sensory appeal, weight control, natural content, mood, familiarity,
and ethical concerns. Renner, Sproesser, Strohbach, & Schupp [37] developed The Eating Moti- vations Survey (TEMS), a broad, multidimensional measure of 15 different motives including liking, habits, hunger, health, convenience, pleasure, tradition, nature, sociability, price, visual
appeal, weight control, affect regulation, social norms, and social image. These multiscale mea-
sures provide a general taxonomy of individual motivations in food choice, but they do not dis-
tinguish the three core motives most central to vegetarian diets, and they include a variety of
motives that are less relevant for plant-based diets such as mood or affect regulation.
Other measures have focused more specifically on ideological or ethical factors potentially
more relevant to vegetarianism. Lindeman and Stark [38] created a measure with scales
designed to distinguish ideological reasons, weight control, health, and pleasure. In a similar
project, Arbit, Ruby, and Rozin [39] crafted the Meaning in Food Life Questionnaire (MFLQ), which has three dimensions, social, sacred (i.e., religious), and aesthetic, that are not relevant
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 2 / 20
is not owned by the authors. It can be requested at
https://www.lissdata.nl. Preregistration, materials,
and data for sample 4 are available at https://osf.io/
9wre4/.
Funding: Funding was provided to Christopher J.
Hopwood and Wiebke Bleidorn by Animal Charity
Evaluators (https://animalcharityevaluators.org).
The funding agency advised on study design
issues prior to data collection; all decisions about
study design were determined by the authors.
Competing interests: The authors have declared
that no competing interests exist.
to our study, and two that are: moral (which could include animal rights and environmental
motives) and health. Lindeman and Väänänen [40] set out to enhance the FCQ by developing
four scales focused on ethical dimensions, including animal welfare, the environment, politics
(e.g., human rights related to food production), and religion. However, in their study, the ani-
mal welfare and environment scales were so highly correlated that they collapsed into a single
factor. Measures focused on ethical motivations for food choice begin to capture variation in
motives that might be specific to vegetarian diets, but they tend to collapse different ethical
concerns relevant to vegetarian diet into a single factor and don’t always include health. Indeed,
distinguishing various ethical factors may be difficult in practice [21,41,42], as results from
these studies also show that even when items are identified to distinguish moral from health-
related motives, it is challenging to distinguish these motives in terms of external correlates. An
important exception is the Dietarian Identity Questionnaire [2], which has scales designed to measure a range of dimensions that link dietary behavior to identity, including the emphasis an
eater places on prosocial as opposed to moral concerns when making food choices. This frame-
work has considerable promise for identifying the mechanisms underlying these different
motivations for vegetarian diets (e.g., Rosenfeld, 2019 [43]), but it does not provide scales to
directly measure health, environmental, and animal rights motives for a vegetarian diet.
Thus, the first step in our research was to use a construct validation strategy to test whether
the three main reasons people might have adopted or be compelled to adopt a plant-based diet
—health, animal rights, and the environment—can be distinguished empirically. Given ambi-
guities in the literature, we focused specifically on differentiating environmental and animal
rights factors.
Identifying characteristic profiles of people with different
vegetarian motives
Variables related to plant-based eating in general include younger age [44,45], being female
[1,44,46–49], living in urban areas [50–54], and having liberal values [45,46,49,52,55–59].
Thus, vegetarians can be reliably characterized, to some degree, in broad strokes.
Yet, different vegetarians can arrive at a plant-based diet for very different reasons. How are
people who are primarily motivated by their personal health different from people who are
primarily motivated by their concerns about the environment or their compassion for ani-
mals? The second goal of this project is to distinguish people who are most likely to pursue
plant-based diets for reasons related to their personal health, the environment, or animal
rights. Distinct profiles of people with these different motives could help advocacy campaigns
reliably identify individuals and groups who are most likely to respond to their message.
Given the limited evidence regarding correlates of different motivations and the fact that
there is a wide range of plausible correlates, our overall approach was to include an extensive
array of possible attributes with plausible links to vegetarian motives and to use multiple sam-
ples and increasingly strict statistical tests to hone in on replicable associations. We included
attributes related to demographic characteristics, personality traits, values, hobbies, religious
background and behavior, habits, entertainment preferences, and patterns of social media use.
We then 1) identified potential correlates in an American undergraduate convenience sample,
2) identified which associations replicate in an American community convenience sample,
and 3) tested preregistered hypotheses, based on these replicated associations, about which
variables would replicate in a large representative Dutch sample. We reasoned that any associa-
tions observed consistently across all three of these samples would be sufficiently robust to be
useful for informing research on motives for plant-based eating and for guiding advocacy
efforts.
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Vegetarian motives and responsiveness to advocacy materials
The motivational complexity of vegetarian behavior implies that advocacy will generally be
most effective if it targets the specific motives of its audience. This is presumably why advocacy
groups tend to campaign on one of the three main reasons to adopt plant-based diets—health,
the environment, and animal rights. But is it true that people with different levels of health,
environmental, and animal rights motives will be differentially sensitive to advocacy materials
that target their primary motives? The third goal of this project was to use the measure we
developed to determine whether individual differences in motives for vegetarian eating predict
responsiveness to advocacy materials that focus on health, the environment, or animal rights.
Method
This study was approved by the UC Davis IRB #1145613–1 and #1372555–2.
Sample 1
Our first sample consisted of 1006 undergraduates attending a public university in the United
States who participated in exchange for course credit. The mean age of these students was
19.80 (SD = 3.33); 822 (81.7%) were female, 180 (17.9%) male, and 4 (0.4%) nonbinary. Racial
composition was 485 Asian (48.2%), 22 black (2.2%), 47 Latin American (4.7%), 27 Native
American (2.7%), 328 white (32.6%), 94 multiracial (9.3%), and 3 other (0.3%); 252 (25.0%)
reported Hispanic ethnicity. Eleven participants self-identified as vegan and 44 as vegetarian.
Sample 2
Our second sample consisted of 1004 Amazon MTurk Workers who completed a survey for
financial compensation (prorated at $10/hour). The average age in this sample was 36.46
(SD = 10.99); 471 (46.91%) were female, 532 (53.00%) were male, and 1 (0.1%) was nonbinary.
Ethnic/racial composition was 63 (6.7%) Asian, 113 (11.3%) black, 111 (11.1%) Hispanic, 10
(1.0%) Native American, 780 (77.7%) white, 32 (3.2%) multiracial, and 6 (0.6%) other. Partici-
pants in this sample were not restricted based on geography. Seventeen participants self-identi-
fied as vegan and 25 as vegetarian.
Sample 3
Our third sample included 5478 Dutch participants drawn from the Longitudinal Internet
Studies of the Social Sciences (LISS). The mean age in this sample was 51.34 (SD = 18.31);
3,106 (54.0%) were female and 2,642 (46.0%) were male. Sixty-nine participants self-identified
as vegan; vegetarian identity was not assessed in the LISS sample.
Sample 4
Our fourth sample consisted of 739 undergraduate participants (mean age = 20.01, SD = 3,60;
615 women (83.0%); 186 Hispanic (25.0%) ethnicity; 178 white (24.0%), 10 black (1.4%), 363
Asian (49.0%), 4 Pacific Islander (0.5%), 84 multiracial (11.4%), and 95 other race (12.9%).
Eight people reported vegan diet and 27 reported vegetarian diet.
The only exclusion criterion across samples was being 18 years or older. Participants were
not excluded based on dietary habits or preferences.
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Instrument development strategies
Based on an initial literature review, we generated 26 items designed to assess health, environ-
mental, and animal rights motives for a plant-based diet. We administered these items to par-
ticipants in Sample 1 and conducted a series of item-level factor analyses to identify a reduced
set of items that loaded onto the three factors with strong pattern coefficients and minimal
cross-loadings. We then administered and examined this reduced set of items in Sample 2. We
examined the fit of the measurement model within both samples and measurement invariance
across both samples using confirmatory factor analysis (CFA). Items, instructions, and
response scales for the final version of the instrument, which we called the Vegetarian Eating Motives Inventory (VEMI), are given in Table 1.
We translated the VEMI items into Dutch in order to administer it to Sample 3. We first
asked a native Dutch speaker who also speaks English to translate the items. We then asked a
native English speaker who also speaks Dutch to back translate them. The research team con-
firmed that the content was retained for all items through this process. We evaluated the fit of
the measurement model and measurement invariance using CFA. Items, instructions, and
response scales for the Dutch version of the VEMI are available at https://osf.io/wyfgb/.
Validating measures
We sought to measure a wide range of variables that could plausibly distinguish motives for a
plant-based diet. Our main constraint was the measures that already existed in the LISS data
(i.e., Sample 3) to whom we would administer the VEMI but whose data collection was other-
wise already planned. Overall, we assessed 260 characteristics (https://osf.io/y8nd5/). These
characteristics included demographic features, personality traits, terminal and instrumental
values, religious beliefs and behaviors, involvement in various organizations and volunteer
activities, employment/income, hobbies/interests, online behavior and preferences, social
behavior, and habits.
Table 1. Vegetarian Motives Inventory (VEMI). Please rate the importance of each of the following reasons for you
to eat less meat or animal products. Please rate these items even if you don’t intend to change your diet.
Scale:
ss1 2 3 4 5 6 7
Not important Moderately important Very important
1. I want to be healthy (H)
2. Plant-based diets are better for the environment (E)
3. Animals do not have to suffer (A)
4. Animals’ rights are respected (A)
5. I want to live a long time (H)
6. Plant-based diets are more sustainable (E)
7. I care about my body (H)
8. Eating meat is bad for the planet (E)
9. Animal rights are important to me (A)
10. Plant-based diets are environmentally-friendly (E)
11. It does not seem right to exploit animals (A)
12. Plants have less of an impact on the environment than animal products (E)
13. I am concerned about animal rights (A)
14. My health is important to me (H)
15. I don’t want animals to suffer (A)
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PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
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Strategy for identifying correlates of vegetarian motives
Our general approach to identifying specific motive-outcome associations in order to pre-reg-
ister hypotheses for Sample 3 was to estimate a series of multiple latent regressions using the R
package lavaan [60] in Sample 1 that we then attempted to replicate in Sample 2. First, we esti- mated six different models separately: one in which all associations between outcome and the
three latent eating motives variables were constrained to be equal (model All Equal), one in
which all motive-outcome associations were constrained to zero (model All Zero), three in
which one motive-outcome association was estimated freely but the other two motives were
constrained to have equal associations with the outcome (models Animal Free, Environment
Free, and Health Free), and one in which all motive-outcome associations were estimated
freely (model All Free).
We then conducted a series of nested χ2 model comparison tests for each motive-outcome association to identify which of these six models best fit the data. We first compared the fit of
model All Equal to model All Zero. If model All Zero did not fit significantly worse (p < .05), we selected model All Zero as the best fit and concluded that no eating motives were signifi-
cantly associated with the outcome variable. If model All Zero fit worse than model All Free,
we compared the fit of model All Equal to whichever of Animal Free, Environment Free, and
Health Free fit best to the data (as these models have equal degrees of freedom, they were not
nested; the best-fitting model was identified as the one with the lowest χ2 and BIC values). If none of these models fit significantly better than model All Equal, we selected model All Equal
as the best fit and concluded that the three eating motives were not differentially associated
with the outcome variable. However, if Animal Free, Environment Free, or Health Free models
fit significantly better to the data than model All Equal, we compared the fit of that model ver-
sus the fit of model All Free. If model All Free fit significantly better, we concluded that eating
motives were differentially associated with the outcome variable. If All Free did not fit signifi-
cantly better, and Animal Free, Environment Free, or Health Free was the best fitting model,
we concluded that one specific motive was differentially associated with the outcome variable.
The R code used to perform these analyses is available at https://osf.io/49shv/.
Next, we examined whether any patterns of non-zero motive-outcome associations repli-
cated in the MTurk sample. To do this, we estimated two multiple-groups models in lavaan. In
the first model (model Replication), motive-outcome associations from the best-fitting model
identified in Sample 1 (model All Free, Animal Free, Health Free, Environment Free, or All
Equal) were imposed to be equal across both samples. In the second model (model Nonreplica-
tion), motive-outcome associations in Sample 1 were constrained to the best-fitting model,
while motive-outcome associations in Sample 2 were freely estimated. We compared the fits of
these two nested models using a χ2 model comparison test. If model Nonreplication fit the data significantly better (p < .05), we concluded that the pattern of associations did not repli- cate across samples. Otherwise, we concluded that the pattern of associations in Sample 1 rep-
licated in Sample 2.
Although the aforementioned steps described our primary procedure, it had two important
limitations. First, inspection of the path coefficients revealed instances when very similar effect
sizes across samples were classified as non-replications. Second, because these analyses used
multiple regressions, they were also prone to suppression effects. We therefore contextualized
these initial results with two additional rules. First, to restrict our interpretations to meaningful
effects, we examined whether any moderate-or-stronger associations between specific eating
motives and outcomes replicated across samples. To do this, we first identified all outcomes
for which one or more motive-outcome associations was stronger than Beta weights = |.15| in
both samples. We only retained variables with an effect of |.15| or larger. Second, to avoid
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
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interpreting effects that were only present due to statistical suppression, we examined the
bivariate correlations for each replicated motive-criterion association in the first two samples
and discarded the cases in which the regression coefficient and bivariate correlation were of
opposite signs or in which the bivariate correlation was < |.15|.
Vegetarian motives and responsivity to advocacy flyers
We conducted a pre-registered validation study to test the sensitivity of the VEMI scales to
attitudes about advocacy flyers specifically appealing to health, environmental, and animal
rights motives for a plant-based diet (see https://www.vegansociety.com). Participants
answered six questions about each flyer (e.g., this flyer made me want to be vegan) on a scale
from 1–7. Internal consistencies were above .90 for these sets of questions for all three flyers,
and an item-level factor analysis provided strong support for a single factor. We predicted
that scores on the VEMI motives scales would be specifically associated with positive atti-
tudes about the flyer targeting that motive (e.g., health motives would be related to positive
attitudes about the health flyer) as indexed by both significant bivariate correlations and sig-
nificant Beta weights in regression models in which all three VEMI scales are regressed upon
the attitude scales, one at a time.
Results
Pre-registration, methods, measures, scripts, and supplemental results for samples 1–3 as well
as data for samples 1 and 2 are available at https://osf.io/52v6z/. Data for sample 3 can be
requested at https://www.lissdata.nl. Preregistration, materials, and data for sample 4 are avail-
able at https://osf.io/9wre4/.
Developing the Vegetarian Motives Inventory (VEMI)
Fifteen items were chosen from the original pool of 26 (Table 1) based on exploratory factor
analyses in Sample 1. The model fit the data well and was invariant across all three samples
(Table 2). It was also invariant across men and women and across white vs. non-white partici-
pants in samples 1 and 2 (Table 2). Cronbach’s alpha estimates of internal consistency across
the three samples, respectively, were .88, .91, and .89 for the health scale, .90, .94, and .92 for
the environment scale, and .93, .96, and .94 for the animal rights scale. Latent correlations
between these scales in the three samples, respectively, were .33, .40, and .43 between health
and environment, .27, .35, and .49 between health and animal rights, and .57, .70, and .59
between environment and animal rights.
VEMI scale means across our first three samples are given in Table 3. In general, people
tended to respond above the raw midpoint of 4, indicating that health, the environment, and
animal rights are all considered to be generally compelling reasons to adopt a plant-based diet.
This was particularly the case for the health scale, for which the mean approached 6 (out of 7)
in all three samples. As a validity check, we also asked participants in Samples 1 and 2 to rank
the main reason they would choose to adopt a plant-based diet. Of the 1826 participants who
responded to this question, the standardized means for corresponding VEMI scales were con-
sistently ranked as the most important reason (e.g. people who rated Health highest on the
VEMI scale also tended to rank Health as their main reason to adopt a plant-based diet). Again,
these results showed that health is the most common reason among this primarily non-vegetar-
ian sample to consider eating less meat, as 75% of respondents ranked this motive first. Finally,
large effects distinguished the 97 vegans across all three samples from non-vegan respondents
for the health (d = .51), environment (d = 1.29), and animal rights (d = .97) scales (all p < .001; Table 4).
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
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Identifying correlates of plant-based eating motives
Based on an initial examination of criterion variable distributions, the following variables were
log-transformed in order to normalize distributions: gross monthly income, all values, weekly
hours volunteering, weekly hours spent watching sports, weekly hours watching tv, weekly
hours listening to the radio, number of books read in the last 30 days, frequency of social
media use, and hours per week spent online. We also log-transformed these variables in Sam-
ples 2 and 3. We excluded 49 binary variables with insufficient variance in either Samples 1 or
2 (i.e., less than 50 participants responding either “no” or “yes”) and 4 continuous variables
with no variance in Samples 1 or 2. We did not consider any other variables in the LISS sample
that were not also assessed in Samples 1 and 2. Given these exclusions, we examined associa-
tions between VEMI scales and 207 remaining criterion variables.
We first computed bivariate correlations between VEMI scales and the 207 criterion vari-
ables. The 56 criterion variables with replicated associations (p < .01) across all three samples
are presented in Table 5. Among those, most variables correlated with all three motives, with
health motives uniquely, or with both health and animal rights motives.
Table 2. CFA model fit for the VEMI in three samples.
df χ2 CFI RMSEA
Undergraduate sample 1 87 359.97 .975 .056
MTurk sample 2 87 462.52 .975 .065
LISS sample 3 87 3813.69 .948 .086
Invariance tests across three samples
Configural 261 4636.19 .955 .080
Constrain factor loadings 285 4804.38 .954 .078
Constrain intercepts 309 5978.15 .942 .084
Constrain latent means 315 6306.12 .939 .086
Invariance tests across males and females in three samples (N = 7,753)
Configural 174 3884.0 .962 .074
Constrain factor loadings 186 3906.7 .962 .072
Constrain intercepts 198 3969.1 .961 .070
Constrain latent means 201 4166.3 .959 .071
Invariance tests across white and non-white participants in samples 1 and 2 (N = 2,010)
Configural 174 767.38 .977 .058
Constrain factor loadings 186 784.62 .977 .057
Constrain intercepts 198 813.65 .976 .056
Constrain latent means 201 822.39 .976 .055
df = degrees of freedom. CFI = Confirmatory Fit Index. RMSEA = Root Mean Square Error of Approximation. We used model comparison tests based on fit indices to
examine measurement invariance. We established measurement invariance (all ΔCFI < .01 or all ΔRMSEA < .01; cf. Cheung & Rensvold, 2002). That is, we were able to
constrain configuration, factor loadings, intercepts, and latent means across groups without a significant decrease in model fit.
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Table 3. Means and standard deviations for VEMI scales in three samples.
Health Environment Animal Rights
Undergraduate sample 1 5.93 (1.07) 4.38 (1.39) 4.64 (1.46)
Mturk sample 2 5.71 (1.30) 4.25 (1.73) 4.35 (1.79)
LISS sample 3 5.88 (1.09) 4.80 (1.20) 5.27 (1.47)
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PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
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As described above, our primary analytic approach used a regression-based strategy in a
latent-variable framework to test preregistered predictions in sample 3 based on results from
samples 1 and 2. Among the207 criterion variables, we identified 33 that were significantly
associated with at least one VEMI scale in both of the first two samples. Table 6 shows the
results of the best-fitting models for those criterion variables. We based predictions for Sample
3 based on two criteria from analyses of data from samples 1 and 2.: a positive standardized
path coefficient of |.15| or larger and a bivariate correlation of |.15| or larger. Based on these
results, we predicted that a) valuing peace would be related to all three motives (in this case we
relaxed our rule somewhat; although the regression coefficient for animal motives was .14 in
the second sample, bivariate correlations were virtually identical across variables), b) agreeable
personality, valuing truth, responsibility, hard work, forgivingness, courage, helpfulness, lov-
ingness, self-control, independence, instrumental happiness, intellect, family security, free-
dom, self-respect, terminal happiness, wisdom, national security, salvation, friendship,
accomplishment, harmony, comfort, and mature love would have specific associations with
health motives, c) being involved with an environmental organization would have a specific
association with environmental motives, and d) caring for plants or animals would have a spe-
cific association with animal rights motives. Seven variables with standardized regression coef-
ficients above our threshold in both samples did not have bivariate correlations < |.15| and
thus we predicted they would not be related to any plant-based eating motives in the LISS
data. The preregistration document for Sample 3 based on these findings can be found at
https://osf.io/rk4en/. We mistakenly made predictions about three variables based on results
in sample 1 and 2 that were not available in LISS—being vegetarian, eating meat, and being
involved in an animal organization.
Associations that met the replication criteria described in the preceding paragraph are
given in Table 7. Overall, 16 variables were related specifically and positively to health motives,
including the personality trait agreeableness and a number of different values. The only vari-
able that was related specifically to environmental motives was participation in an environ-
mental organization. No variables were related specifically to animal rights motives.
Vegetarian motives and responsivity to advocacy flyers
Participants from Sample 4 completed the VEMI and answered questions about advocacy fly-
ers targeting health, environment, and animal rights motives created by The Vegan Society.
We used these data to test pre-registered hypotheses about the specificity of correlations
between the VEMI scales and attitudes about flyers targeting health, environment, and animal
rights motives (https://osf.io/9wre4/). Table 8 shows that all bivariate correlations between
motives and responses to flyers were statistically significant (p < .05). As predicted, the stron- gest correlate of the environment flyer was the VEMI environment scale and the strongest cor-
relate of the animal rights flyer was the VEMI animal rights scale. Inconsistent with our
hypotheses, both the environment and animal rights scales were also more strongly correlated
with responses to the health flyer, suggesting that people who are motivated by health are not
particularly impacted by vegetarian advocacy, in general.
Table 4. Standardized means for three VEMI scales among people who ranked health, environment, and animal rights as most important factor in considering a
vegetarian diet.
Ranking N Health Scale Environment Scale Animal Rights Scale
Health 1366 .08 (.93) -.18 (.98) -.21 (.98)
Environment 247 -.25 (1.15) .54 (.88) .28 (.83)
Animal Rights 213 -.31 (1.26) .34 (1.04) .96 (.75)
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Table 5. Bivariate correlations between plant-based motives and criterion variables for which at least one motive correlated significantly (p < .01) across samples 1,
2, and 3.
Sample Health Environment Animal Rights
1 2 3 1 2 3 1 2 3
Male -.08 -.08 -.11 -.16 -.04 -.15 -.28 -.07 -.18
Extraversion .17 .16 .14 .06 .16 .03 -.01 .11 .04
Agreeableness .26 .32 .21 .15 .20 .19 .21 .17 .23
Conscientiousness .15 .23 .20 .06 .09 .07 .13 .07 .09
Neuroticism .10 .11 .09 -.05 -.02 -.03 -.05 -.06 -.08
Openness .13 .22 .00 .09 .15 .10 .11 .16 .01
Truth .28 .30 .14 .16 .12 .06 .22 .13 .10
Responsible .24 .31 .15 .08 .13 .07 .12 .13 .12
Hard-working .28 .27 .16 .12 .11 .00 .16 .07 .05
Forgiving .17 .28 .15 .10 .16 .14 .14 .12 .12
Open-minded .21 .16 .18 .17 .26 .12 .22 .25 .14
Courageous .21 .26 .20 .11 .19 .09 .15 .18 .13
Helpful .28 .32 .16 .14 .26 .11 .16 .20 .17
Loving .25 .34 .18 .14 .19 .11 .17 .17 .17
Capable .18 .31 .15 .15 .10 .07 .19 .09 .09
Clean .16 .29 .21 .13 .18 .03 .15 .16 .10
Self-controlled .22 .23 .19 .10 .07 .02 .13 .09 .08
Independent .17 .24 .12 .12 .11 .08 .13 .11 .13
Happy .29 .29 .20 .11 .15 .06 .14 .14 .10
Polite .19 .26 .19 .09 .12 .05 .15 .10 .13
Intellectual .19 .24 .11 .10 .17 .09 .13 .14 .04
Obedient .12 .18 .18 .00 .03 -.01 .03 .03 .05
Logical .12 .25 .10 .11 .07 .05 .08 .07 .03
Creative .13 .28 .12 .11 .25 .15 .14 .25 .14
Peace .27 .33 .26 .29 .30 .25 .30 .29 .27
Family Security .24 .33 .18 .05 .08 .01 .13 .09 .09
Freedom .26 .26 .17 .15 .05 .09 .21 .12 .16
Equality .23 .20 .17 .25 .35 .18 .29 .29 .21
Self-respect .30 .34 .22 .15 .14 .11 .15 .15 .17
Happiness .32 .32 .20 .10 .15 .07 .14 .14 .16
Wisdom .22 .34 .15 .10 .18 .14 .10 .17 .16
National Security .25 .27 .27 .09 .03 .10 .13 .07 .20
Salvation .15 .22 .20 .01 .04 .06 .06 .06 .13
Friendship .22 .33 .20 .11 .18 .10 .14 .18 .16
Accomplishment .24 .32 .17 .14 .16 .01 .14 .13 .05
Inner Harmony .24 .35 .24 .16 .25 .19 .15 .25 .22
A comfortable life .20 .24 .16 .10 .05 .02 .13 .07 .09
Mature love .23 .23 .20 .14 .13 .06 .11 .08 .11
Beauty .14 .25 .20 .15 .31 .12 .15 .30 .11
Pleasure .17 .21 .17 .13 .14 .04 .10 .12 .13
Recognition .17 .11 .14 .12 .17 .03 .07 .10 .02
Excitement .24 .17 .13 .14 .19 .03 .15 .17 .06
Leisure satisfaction .10 .14 .14 .00 .13 .04 .01 .06 .04
Social life satisfaction .13 .17 .13 .01 .15 .05 .06 .08 .04
Social Connectedness .18 .10 .09 .03 .01 .03 .05 -.05 -.01
(Continued)
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Regression models confirmed primary associations between the environment motives and
responses to the environment flyer and animal rights motives to the animal rights flyer. The
VEMI environment scale emerged as the only significant predictor in the regression model for
the health flyer. These preregistered regression models tested associations between vegetarian
motives and responses to the flyers, controlling for other vegetarian motives. We conducted
exploratory analyses in which we reversed the independent and dependent variables in our
regression analyses, to test whether flyers would have specific relations with motives, control-
ling for the responses to other flyers. In those models, responses to the health flyer emerged as
the only significant predictor of the VEMI health scale (β = .15). Likewise, responses to the environment and animal rights flyers were the only significant predictors of the VEMI envi-
ronment and animal rights scales, respectively. This pattern indicates that, controlling for
general motives to be a vegetarian, there are no specific links between health motives and
responses to health-focused advocacy, whereas controlling for general responsivity to advo-
cacy, there may be specific links between health-focused advocacy and health-related vegetar-
ian motives. Overall, the results support the utility of targeting advocacy based on the
environment or animal rights to people most likely to care about those issues, and provide
weak to mixed support for targeting advocacy based on health motives.
Discussion
The variety of pathways that can lead a person to vegetarian diet raises the possibility that-
people who select different pathways are also different in other ways, but little is known about
these differences or their importance for eating behavior. Thus, the purposes of this study were
to develop a measure of health, environmental, and animal rights motives for vegetarian eat-
ing, examine the correlates of these dimensions, and test whether motives differentially predict
responses to advocacy materials.
Vegetarian eating motives inventory
Our first step was to develop the Vegetarian Eating Motives Inventory (VEMI), a measure that reliably distinguishes between health, environmental, and animal rights motives for plant-
Table 5. (Continued )
Sample Health Environment Animal Rights
1 2 3 1 2 3 1 2 3
Involved in religious organization .03 .12 .00 -.06 -.05 -.01 -.07 -.08 -.11
Involved in environmental organization .01 .06 -.02 .21 .25 .20 .13 .17 .11
Involved in humanity organization -.01 .06 -.02 .13 .17 .15 .12 .14 .04
Visited a museum -.02 .09 -.03 .08 .11 .13 .02 .07 -.03
Crafts .02 .07 .04 .07 .07 .11 .13 .08 .10
Care for plants/animals .07 .10 .09 .12 .16 .11 .17 .19 .13
Uses Linkedin .08 .07 -.07 -.01 .07 -.03 .00 .06 -.13
Self religious status .11 .17 .08 -.05 .00 .00 -.02 -.01 -.05
Believe in God .20 .22 .15 -.05 -.07 .05 .07 -.01 .02
Believe in afterlife .09 .15 .09 -.02 -.03 .06 -.02 -.13 .05
Believe in heaven .12 .11 .09 -.02 .01 .01 -.04 -.14 .00
Frequency of praying .12 .16 .08 -.05 -.02 .03 -.03 -.03 -.02
Significant correlations (p < .01) in bold.
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based diets. The scales of this brief instrument were internally consistent and demonstrated a
robust factor structure, including measurement invariance across three samples in two lan-
guages, men and women, and white and non-white participants. This measure has consider-
able promise for future research on the motivations for plant-based eating in Western
cultures. Moreover, although our goal was to develop the VEMI to assess the potential motives
of non-vegetarians in a general population, it can be easily adapted for research among vegans,
vegetarians, flexitarians, reducetarians, and other groups. It could also be used at an individual
level to better understand the kinds of factors that might be most influential for a particular
person. The VEMI thus provides researchers and advocates with a well-validated and flexible
Table 6. Variables with significant associations to plant-based eating motives in two convenience samples.
Variable Undergraduate Sample 1 MTurk Sample 2
Best Model Health Environment Animal Replicate Health Environment Animal
vegan Free All -.19 .56 .19 Yes -.17 .34 .35
peace Health Free .18 .16 .15 Yes .21 .15 .14
agreeableness Free All .22 -.01 .16 No .28 .10 .01
truth Free All .26 -.01 .16 Yes .26 -.01 .10
responsible Health Free .25 .02 .02 Yes .26 .02 .01
hard working Health Free .28 .04 .03 Yes .23 .02 .02
forgiving Health Free .15 .05 .05 Yes .19 .04 .04
courageous Health Free .20 .05 .04 Yes .19 .06 .05
helpful Health Free .26 .05 .05 No .23 .19 .00
loving Health Free .22 .06 .06 Yes .23 .05 .05
self-controlled Health Free .20 .04 .04 Yes .23 .02 .02
independent Health Free .16 .05 .05 Yes .20 .03 .03
happy Health Free .30 .03 .02 Yes .26 .03 .03
intellectual Health Free .17 .05 .04 Yes .19 .05 .04
family security Free All .25 -.08 .11 No .34 -.04 .01
freedom Free All .24 .00 .16 No .27 -.15 .14
self-respect Health Free .28 .05 .04 Yes .31 .03 .03
happiness Health Free .32 .02 .02 Yes .28 .02 .02
wisdom Health Free .21 .03 .03 Yes .27 .03 .03
national security Health Free .23 .03 .03 No .25 -.09 .05
salvation Health Free .16 -.01 -.01 Yes .17 -.01 -.01
friendship Health Free .21 .04 .04 Yes .22 .04 .04
accomplishment Health Free .21 .05 .05 Yes .24 .04 .04
harmony Health Free .22 .06 .06 Yes .26 .08 .08
comfort Health Free .18 .04 .04 Yes .20 .02 .01
mature love Health Free .19 .05 .05 Yes .19 .04 .03
connectedness Health Free .18 -.01 -.01 No .15 .05 -.14
environmental organization Environment Free -.01 .22 -.01 Yes -.02 .28 -.02
visited opera Environment Free -.17 .16 -.22 No -.01 .21 .02
conscientiousness Environment Free .10 -.06 .15 Yes .11 -.06 .15
capable Environment Free .12 .01 .18 Yes .14 -.05 .20
polite Environment Free .12 -.05 .17 Yes .11 -.04 .16
crafts Animal Free -.01 -.02 .19 Yes .03 -.02 .15
care for plants/animals Animal Free .03 .04 .19 Yes .04 .04 .22
Coefficients represent beta weights from Structural Equation Models.
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measure for assessing the primary motives for plant-based eating among various individuals
and groups.
Eating motivation profiles
We next used the VEMI scale to identify profiles of individuals who are most sympathetic to
different reasons to be vegetarian. Overall, findings from three diverse samples suggested that
health motives are the most common reason to consider adopting a plant-based diet in general
and that health motives have the broadest array of correlates.
A number of criteria reliably correlated with plant-based motives across samples. By this
standard, 21 variables correlated with all three motives. The common thread in this list seemed
to be a communal orientation to life (e.g., agreeableness, loving, and valuing peace). The pro-
file of people motivated by health was more conventional, as defined by 20 variables (e.g.,
male, hard-working, obedient, life satisfaction, and religiosity). The only variables that corre-
lated uniquely with environmental motives were openness to experience and having visited a
museum. Being involved in a religious organization and doing crafts were uniquely related to
Table 7. Replicated associations in the LISS sample.
Variable Path Coefficients Pearson Correlations
Health Environment Animal Health Environment Animal
agreeableness .15 .09 .09 .21 .19 .23
hard working .21 -.04 -.04 .16 .00 .05
courageous .19 .02 .02 .20 .09 .13
loving .15 -.01 .10 .18 .11 .17
self-controlled .23 -.09 .02 .19 .02 .08
happy .22 -.01 -.01 .20 .06 .10
family security .20 -.10 .05 .18 .01 .09
self-respect .20 -.02 .09 .22 .11 .17
happiness .18 -.07 .12 .20 .07 .16
national security .26 -.09 .13 .27 .10 .20
salvation .19 -.05 .08 .20 .06 .13
friendship .17 -.03 .10 .20 .10 .16
accomplishment .21 -.07 .00 .17 .01 .05
harmony .18 .08 .08 .24 .19 .22
comfort .18 -.09 .06 .16 .02 .09
mature love .22 -.05 .04 .20 .06 .11
environmental organization -.14 .23 .05 -.02 .20 .11
Coefficients represent beta weights from Structural Equation Models. Variables were included in this table if they replicated results from the first two samples.
https://doi.org/10.1371/journal.pone.0230609.t007
Table 8. Correlations and regression coefficients indicating associations between VEMI scale scores and attitudes about advocacy flyers.
Flyer Health Environment Animal Rights
VEMI Scale r β r β r β
Health .17� .06 .09� -.07 .15� -.02
Environment .32� .26� .45� .39� .36� .20�
Animal Rights .25� .09 .32� .14� .42� .32�
R2 .12� .21� .12�
� p < .05
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the animal rights motive. Valuing intellectual pursuits was related to both health and environ-
mental motives, whereas being involved in a humanity organization was related to both envi-
ronmental and animal rights motives. Finally, nine variables were related to both health and
animal rights motives. As a group, they seemed to involve morality (e.g., conscientiousness,
valuing truth, being self-controlled).
In our primary analytic approach, we used a more restrictive strategy with latent variables
to account for measurement error and regression models to identify unique associations with
each of the plant-based motives. Based on this approach, people who were primarily motivated
by their health tended to be more agreeable, to have instrumental values (i.e. preferred means
of achieving goals) involving hard work, courage, love, self-control, being happy, and to have
terminal values (i.e., desired end states) involving family security, self-respect, happiness,
national security, salvation, friendship, accomplishment, harmony, comfort, and mature love.
This pattern paints a picture of a fairly conventional person who views working hard and get-
ting along with others as the formula for a good life. In general, people whose main motives
for considering a vegetarian diet are related to their health were not particularly compelled by
vegetarian flyers, regardless of their content.
The only criterion uniquely and reliably related to environmental motives was participation
in an environmental rights organization. No criteria were reliably related to animal rights
motives across all three samples based on our primary analytic strategy. These circumscribed
findings for the environment and animal rights scales surprised us given the large number of
correlates we examined. This could have to do with our relatively conservative analytic approach,
given the larger number of findings based on bivariate correlations that were significant at p < .01. However, by and large these results suggest that few traits, values, hobbies, habits, or demo-
graphic characteristics correlate in a way that is both robust and specific to the two major ethical
motives for plant-based eating. This may suggest that “ethical vegetarianism” is a moral issue
with relative specificity, as exemplified by the large numbers of people who actively promote
social justice and environmental protection yet continue to eat animals. While there was some
specificity between animal rights/environmental motives and responsivity to animal rights/envi-
ronmental flyers, a more general finding is that people with ethical motives to consider a vegetar-
ian diet were more responsive to advocacy flyers, including one that emphasized health benefits.
Implications for targeted advocacy
This pattern of results presents a kind of paradox for targeted advocacy. The most common
reason people say they would consider being vegetarian has to do with health, and this study
identified factors that could be used to identify those people. However, people driven primarily
by health motives are least likely to respond to vegetarian advocacy. One interpretation of
these results is that most people care about their health, but most people don’t connect health
to vegetarian diet because the connection is indeed tenuous empirically. The fact that the most
common reason people cite for considering a vegetarian diet is also the least compelling may
help explain why there continues to be relatively few vegetarians, and why people motivated by
health are also least strict [41,45,61–63] and compliant [1,64,65] with a vegetarian diet. Our
data also supports this view somewhat, in that being vegan was more strongly associated with
animal and plant motives than health motives in all three samples, although it did not surpass
our cutoff in Sample 1 (correlations were .12 with both the animal and environment scales).
Conversely, people who are sympathetic to the ethical arguments for a vegetarian diet can-
not easily be distinguished in other ways, but they are most likely to respond to vegetarian
advocacy. The one exception is the relatively unsurprising finding that people affiliated with
environmental advocacy groups are most likely to respond to an environmental argument
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supports the idea of encouraging individuals motivated by such concerns to see the connection
between plant-based diets and climate change (e.g., [66]). Indeed, it is likely that many individ-
uals who are passionate about this issue are not fully informed about the negative environmen-
tal impact of eating meat [67], and this information gap could be usefully exploited by animal
advocacy groups who target individuals with a demonstrated interest in environmental
activism.
However, overall these results do not seem to support the utility of selecting advocacy mate-
rials based on the kinds of people those materials would target. Instead, these results provide
important information about ways in which targeted advocacy might not be productive. For
instance, none of the demographic features that are known to be associated with plant-based
eating in general, such as being young [44,45], female [1,44,46–49,63] and liberal
[45,46,49,52,55–59], were differentially associated with health, environmental, or animal rights
motives. The higher rates of vegetarianism among such individuals suggest that they represent
fruitful targets for advocacy in general, but the results of this study do not provide guidance
about which motives to appeal to among them, in particular.
It is worth noting that approaches to advocacy may depend on the end goal and beliefs
about the best way to achieve that goal. Animal rights advocates [29,68] have argued that vege-
tarian advocacy should always focus on ethical motives. The more practical sector of plant-
based diet advocacy (e.g., Leenaert, 2017; Joy, 2008 [30,31]) may be relatively more receptive to
emphasizing health as a potential first step in reducing meat consumption. Our results about
the specific correlates of health motives may help guide this step. Ultimately, evidence that
links motives, advocacy approaches, and behavior change will determine the best way to reduce
meat consumption in general, and we suspect that a multipronged approach may prove most
effective [69].
Limitations and future directions
Although we examined a large number of criteria, we were constrained by the data collected
by LISS and it is likely that we missed important unmeasured variables that would specifically
correlate with different vegetarian motives. Likewise, while health, the environment, and ani-
mal rights are the most common motives for plant-based diets in Western societies, certain
individuals may have more specific reasons that are not sampled on the VEMI, such as those
related to religion or taste. Specificity may also be required to better understand the resistance
to vegetarian diets. For instance, concerns have been raised about the difficulties poorer people
have in finding healthy plant-based food, and this poses a considerable challenge to plant-
based diet advocates for whom positioning one form of social justice (i.e., animal rights)
against another (i.e., opportunities for the underprivileged) does little good.
A second major limitation is that the current results do not inform specific strategies to
encourage people with different motives to change their diets in practice. For instance, some
research suggested that people change their behavior upon becoming more aware of the
impacts of eating animals [34,65,70–72], whereas other research suggested that increasing peo-
ple’s awareness alone may not be sufficient to effectively change their behavior [31,73]. This
issue sits downstream from the goals of our work, but it is equally critical for the ultimate goals
of understanding the transition to vegetarian diets.
Third, in this study we exclusively employed self-report measures because we were inter-
ested in consciously accessible motives. However, future work examining attitudes that may be
outside of peoples’ conscious awareness as well as directly behavioral outcome variables would
be a useful extension of the current studies. Fourth, further work could be done to understand
the underlying mechanisms of different attitudes towards plant-based dieting and animals
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[74]. Fifth, we focused in this study on distinguishing among the three major non-religious
motives for vegetarian diet, because research suggests that these are the most common motives
in general and because advocacy focuses almost exclusively on these three reasons to avoid
meat. However, our results suggest that the VEMI scales could be combined into an overall
composite useful for examining motives for vegetarian diet in general, in that the scales were
intercorrelated and each distinguished vegan from non-vegan respondents. Moreover, there
may be considerable value in assessing motives beyond those measured by the VEMI.
Finally, different approaches to the one taken here may be useful for identifying profiles of
people who will tend to respond to different forms of activism. For example, machine learning
approaches can be used in very large samples of users to identify an array of online behaviors
that may be related to different motives for plant-based diets. This is a powerful tool that may
have applicability, for instance in sampling online behavior to produce algorithms that can tar-
get specified audiences from within social media platforms [75]. Another is that considering
the motives in favor of meat-eating [76] may prove useful in identifying the best way of encour-
aging plant-based diets. In a previous, preliminary study, we found that health motives were
unrelated to motives for eating meat, whereas the environmental and animal rights motives
were negatively related to seeing meat eating as “normal” or “nice” [77]. Future work that
examines the links between motives to avoid meat and motives to eat meat would accordingly
be informative.
Conclusion
In this study, we developed the Vegetarian Eating Motives Inventory (VEMI), a brief and
psychometrically robust measure of the three main motives for adopting a plant-based diet:
health, the environment, and animal rights. We used this measure to identify profiles of people
most likely to respond to appeals to these different motives and to test whether motives predict
responses to advocacy materials. In a general populati0n, health motives are the most common
and have the widest array of correlates, which generally involve agentic and communal values.
However, people who cite health motives were relatively unresponsive to advocacy materials
compared to people who cite environmental or animal rights motives.
Author Contributions
Conceptualization: Christopher J. Hopwood, Wiebke Bleidorn.
Data curation: Christopher J. Hopwood, Wiebke Bleidorn, Sophia Chen.
Formal analysis: Christopher J. Hopwood, Wiebke Bleidorn, Ted Schwaba, Sophia Chen.
Funding acquisition: Christopher J. Hopwood, Wiebke Bleidorn.
Investigation: Christopher J. Hopwood, Wiebke Bleidorn.
Methodology: Christopher J. Hopwood, Wiebke Bleidorn.
Project administration: Christopher J. Hopwood, Wiebke Bleidorn.
Resources: Christopher J. Hopwood, Wiebke Bleidorn.
Software: Christopher J. Hopwood, Wiebke Bleidorn.
Supervision: Christopher J. Hopwood, Wiebke Bleidorn.
Writing – original draft: Christopher J. Hopwood.
Writing – review & editing: Christopher J. Hopwood, Wiebke Bleidorn, Ted Schwaba.
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
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References 1. Ruby MB. Vegetarianism. A blossoming field of study. Appetite. 2012; 58:141–50. https://doi.org/10.
1016/j.appet.2011.09.019 PMID: 22001025
2. Rosenfeld DL, Burrow AL. Development and validation of the Dietarian Identity Questionnaire: Assess-
ing self-perceptions of animal-product consumption. Appetite. 2018; 127:182–94. https://doi.org/10.
1016/j.appet.2018.05.003 PMID: 29746880
3. Šimčikas S. IS THE PERCENTAGE OF VEGETARIANS AND VEGANS IN THE U.S. INCREASING? [Internet]. Animal Charity Evaluators. 2018. https://animalcharityevaluators.org/blog/is-the-percentage-
of-vegetarians-and-vegans-in-the-u-s-increasing/#review.
4. Aston LM, Smith JN, Powles JW. Impact of a reduced red and processed meat dietary pattern on dis-
ease risks and greenhouse gas emissions in the UK: a modelling study. BMJ Open. 2012; 2(5):
e001072. https://doi.org/10.1136/bmjopen-2012-001072 PMID: 22964113
5. Baines S, Powers J, Brown WJ. How does the health and well-being of young Australian vegetarian and
semi-vegetarian women compare with non-vegetarians? Public Health Nutr. 2007 May; 10(5):436–42.
https://doi.org/10.1017/S1368980007217938 PMID: 17411462
6. Dyett PA, Sabaté J, Haddad E, Rajaram S, Shavlik D. Vegan lifestyle behaviors. An exploration of con-
gruence with health-related beliefs and assessed health indices. Appetite. 2013 Aug; 67:119–24.
https://doi.org/10.1016/j.appet.2013.03.015 PMID: 23583444
7. Kaluza J, Wolk A, Larsson SC. Red meat consumption and risk of stroke: A meta-analysis of prospec-
tive studies. Stroke. 2012; 43:2556–60. https://doi.org/10.1161/STROKEAHA.112.663286 PMID:
22851546
8. Robinson-O’Brien R, Perry CL, Wall MM, Story M, Neumark-Sztainer D. Adolescent and Young Adult
Vegetarianism: Better Dietary Intake and Weight Outcomes but Increased Risk of Disordered Eating
Behaviors. J Am Diet Assoc. 2009; 109:648–55. https://doi.org/10.1016/j.jada.2008.12.014 PMID:
19328260
9. Godfray HCJ, Aveyard P, Garnett T, Hall JW, Key TJ, Lorimer J, et al. Meat consumption, health, and
the environment. Science. 2018; 361(6399):eaam5324. https://doi.org/10.1126/science.aam5324
PMID: 30026199
10. Green R, Milner J, Dangour AD, Haines A, Chalabi Z, Markandya A, et al. The potential to reduce green-
house gas emissions in the UK through healthy and realistic dietary change. Clim Change. 2015;
129:253–65.
11. Joyce A, Hallett J, Hannelly T, Carey G. The impact of nutritional choices on global warming and policy
implications: examining the link between dietary choices and greenhouse gas emissions. Energy Emiss
Control Technol. 2014; 2:33–43.
12. Bastian B, Loughnan S, Haslam N, Radke HRM. Don’t mind meat? The denial of mind to animals used
for human consumption. Pers Soc Psychol Bull. 2012 Feb; 38(2):247–56. https://doi.org/10.1177/
0146167211424291 PMID: 21980158
13. Bilewicz M, Imhoff R, Drogosz M. The humanity of what we eat: Conceptions of human uniqueness
among vegetarians and omnivores. Eur J Soc Psychol. 2011 Mar; 41(2):201–9.
14. Caviola L, Everett JAC, Faber NS. The moral standing of animals: Towards a psychology of speciesism.
J Pers Soc Psychol. 2019 Jun; 116(6):1011–29. https://doi.org/10.1037/pspp0000182 PMID: 29517258
15. Hirschler CA. “What pushed me over the edge was a deer hunter”: Being vegan in North America. Soc
Anim. 2011; 19:156–74.
16. Izmirli S, Phillips CJC. The relationship between student consumption of animal products and attitudes
to animals in Europe and Asia. Br Food J. 2011; 113:436–50.
17. Loughnan S, Haslam N, Bastian B. The role of meat consumption in the denial of moral status and mind
to meat animals. Appetite. 2010; 55:156–9. https://doi.org/10.1016/j.appet.2010.05.043 PMID:
20488214
18. Lund TB, McKeegan DEF, Cribbin C, Sandøe P. Animal ethics profiling of vegetarians, vegans and meat-eaters. Anthrozoos. 2016; 29:89–106.
19. Preylo BD, Arikawa H. Comparison of vegetarians and non-vegetarians on pet attitude and empathy.
Anthrozoos. 2008; 21:387–95.
20. Cooney N. Veganomics: the surprising science on vegetarians, from the breakfast table to the bedroom.
New York: Lantern Books; 2014. 194 p.
21. Fox N, Ward K. Health, ethics and environment: A qualitative study of vegetarian motivations. Appetite.
2008 Mar; 50(2–3):422–9. https://doi.org/10.1016/j.appet.2007.09.007 PMID: 17980457
22. Kerschke-Risch P. Vegan diet: Motives, approach and duration. Initial results of a quantitative sociologi-
cal study. Ernahrungs Umsch. 2015; 62:98–103.
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 17 / 20
23. Rosenfeld DL, Burrow AL. Vegetarian on purpose: Understanding the motivations of plant-based diet-
ers. Appetite. 2017; 116:456–63. https://doi.org/10.1016/j.appet.2017.05.039 PMID: 28551111
24. Rosenfeld DL, Burrow AL. The unified model of vegetarian identity: A conceptual framework for under-
standing plant-based food choices. Appetite. 2017; 112:78–95. https://doi.org/10.1016/j.appet.2017.01.
017 PMID: 28109732
25. Bobić J, Cvijetić S, Barić IC, Satalić Z. Personality traits, motivation and bone health in vegetarians. Coll Antropol. 2012 Sep; 36(3):795–800. PMID: 23213935
26. Vainio A, Niva M, Jallinoja P, Latvala T. From beef to beans: Eating motives and the replacement of ani-
mal proteins with plant proteins among Finnish consumers. Appetite. 2016; 106:92–100. https://doi.org/
10.1016/j.appet.2016.03.002 PMID: 26952560
27. Furnham A, McManus C, Scott D. Personality, empathy and attitudes to animal welfare. Anthrozoos.
2003; 16:135–46.
28. Mathews S, Herzog HA. Personality and attitudes toward the treatment of animals. Soc Anim. 1997;
5:169–75.
29. Ball M, Friedrich B. The animal activists’ handbook: maximizing our positive impact in today’s world.
New York: Lantern Books; 2009. 117 p.
30. Joy M. Strategic action for animals: a handbook on strategic movement building, organizing, and activ-
ism for animal liberation. New York: Lantern Books; 2008.
31. Leenaert T. How to create a vegan world: a pragmatic approach. New York: Lantern Books; 2017.
32. Lea E, Worsley A. Influences on meat consumption in Australia. Appetite. 2001; 36:127–36. https://doi.
org/10.1006/appe.2000.0386 PMID: 11237348
33. Rimer BK, Kreuter MW. Advancing tailored health communication: A persuasion and message effects
perspective. J Commun. 2006; 56:S184–201.
34. Tiplady CM, Walsh DB, Phillips JC. The ongoing impact of domestic violence on animal welfare. Anim
Stud J. 2015; 4:116–39.
35. Jackson B, Cooper ML, Mintz L, Albino A. Motivations to eat: Scale development and validation. J Res
Personal. 2003; 37:297–318.
36. Steptoe A, Pollard TM, Wardle J. Development of a measure of the motives underlying the selection of
food: The food choice questionnaire. Appetite. 1995; 25:267–84. https://doi.org/10.1006/appe.1995.
0061 PMID: 8746966
37. Renner B, Sproesser G, Strohbach S, Schupp HT. Why we eat what we eat. The Eating Motivation Sur-
vey (TEMS). Appetite. 2012; 59:117–28. https://doi.org/10.1016/j.appet.2012.04.004 PMID: 22521515
38. Lindeman M, Stark K. Pleasure, pursuit of health or negotiation of identity? Personality correlates of
food choice motives among young and middle-aged women. Appetite. 1999; 33:141–61. https://doi.org/
10.1006/appe.1999.0241 PMID: 10447986
39. Arbit N, Ruby M, Rozin P. Development and validation of the meaning of food in life questionnaire
(Mflq): Evidence for a new construct to explain eating behavior. Food Qual Prefer. 2017 Jul; 59:35–
45.
40. Lindeman M, Väänänen M. Measurement of ethical food choice motives. Appetite. 2000; 34:55–9.
https://doi.org/10.1006/appe.1999.0293 PMID: 10744892
41. Hoffman SR, Stallings SF, Bessinger RC, Brooks GT. Differences between health and ethical vegetari-
ans. Strength of conviction, nutrition knowledge, dietary restriction, and duration of adherence. Appetite.
2013; 65:139–44. https://doi.org/10.1016/j.appet.2013.02.009 PMID: 23416470
42. Jabs J, Devine CM, Sobal J. Model of the process of adopting vegetarian diets: Health vegetarians and
ethical vegetarians. J Nutr Educ Behav. 1998; 30:196–202.
43. Rosenfeld DL. Why some choose the vegetarian option: Are all ethical motivations the same? Motiv
Emot. 2019; 43:400–11.
44. Haddad EH, Tanzman JS. What do vegetarians in the United States eat? Am J Clin Nutr. 2003; 78
(3):626S–632S.
45. White RF, Seymour J, Frank E. Vegetarianism among US women physicians. J Am Diet Assoc. 1999;
99(5):595–8. https://doi.org/10.1016/S0002-8223(99)00146-7 PMID: 10333783
46. Beardsworth A, Bryman A. Meat consumption and vegetarianism among young adults in the UK: An
empirical study. Br Food J. 1999 May; 101(4):289–300.
47. Gale CR, Deary IJ, Batty GD, Schoon I. IQ in childhood and vegetarianism in adulthood: 1970 British
cohort study. Br Med J. 2007; 334(245).
48. Phillips CJC, Izmirli S, Aldavood SJ, Alonso M, Choe BI, Hanlon A, et al. Students’ attitudes to animal
welfare and rights in Europe and Asia. Anim Welf. 2012; 21:87–100.
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 18 / 20
49. Ruby MB, Heine SJ. Meat, morals, and masculinity. Appetite. 2011; 56:447–50. https://doi.org/10.1016/
j.appet.2011.01.018 PMID: 21256169
50. de Boer J, Aiking H. On the merits of plant-based proteins for global food security: Marrying macro and
micro perspectives. Ecol Econ. 2011 May; 70(7):1259–65.
51. Hoek AC, Luning PA, Stafleu A, De Graaf C. Food-related lifestyle and health attitudes of Dutch vege-
tarians, non-vegetarian consumers of meat substitutes, and meat consumers. Appetite. 2004; 42:265–
72. https://doi.org/10.1016/j.appet.2003.12.003 PMID: 15183917
52. Kalof L, Dietz T, Stern PC, Guagnano GA. Social Psychological and Structural Influences on Vegetarian
Beliefs. Rural Sociol. 2009 Oct 22; 64(3):500–11.
53. Rimal AP. Factors affecting meat preferences among American consumers. Fam Econ Nutr Rev. 2002;
14:36–43.
54. Vinnari M, Mustonen P, Räsänen P. Tracking down trends in non-meat consumption in Finnish house-
holds, 1966–2006. Br Food J. 2010; 112:836–52.
55. Allen MW, Wilson M, Ng SH, Dunne M. Values and beliefs of vegetarians and omnivores. J Soc Psy-
chol. 2000 Aug; 140(4):405–22. https://doi.org/10.1080/00224540009600481 PMID: 10981371
56. Chin MG, Fisak B, Sims VK. Development of the attitudes toward vegetarians scale. Anthrozoös. 2002
Dec; 15(4):332–42.
57. Dietz T, Frisch AS, Kalof L, Stern PC, Guagnano GA. Values and vegetarianism: an exploratory analy-
sis1. Rural Sociol. 2010 Feb 3; 60(3):533–42.
58. Spencer EH, Elon LK, Frank E. Personal and Professional Correlates of US Medical Students’ Vege-
tarianism. J Am Diet Assoc. 2007; 107:72–8. https://doi.org/10.1016/j.jada.2006.10.034 PMID:
17197274
59. Worsley A, Skrzypiec G. Teenage vegetarianism: Prevalence, social and cognitive contexts. Appetite.
1998; 30:151–70. https://doi.org/10.1006/appe.1997.0118 PMID: 9573450
60. Rosseel Y. Lavaan: An R package for structural equation modeling and more. J Stat Softw. 2012; 48:1–
36.
61. Radnitz C, Beezhold B, DiMatteo J. Investigation of lifestyle choices of individuals following a vegan diet
for health and ethical reasons. Appetite. 2015; 90:31–6. https://doi.org/10.1016/j.appet.2015.02.026
PMID: 25725486
62. Rothgerber H. A comparison of attitudes toward meat and animals among strict and semi-vegetarians.
Appetite. 2014; 72:98–105. https://doi.org/10.1016/j.appet.2013.10.002 PMID: 24148251
63. Rozin P, Markwith M, Stoess C. Moralization and becoming a vegetarian: The Transformation of Prefer-
ences into Values and the Recruitment of Disgust. Psychol Sci. 1997; 8:67–73.
64. Barr SI, Chapman GE. Perceptions and practices of self-defined current vegetarian, former vegetarian,
and nonvegetarian women. J Am Diet Assoc. 2002 Mar; 102(3):354–60. https://doi.org/10.1016/s0002-
8223(02)90083-0 PMID: 11902368
65. Haverstock K, Forgays DK. To eat or not to eat. A comparison of current and former animal product lim-
iters. Appetite. 2012; 58:1030–6. https://doi.org/10.1016/j.appet.2012.02.048 PMID: 22387715
66. Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Sci-
ence. 2018; 360:987–92. https://doi.org/10.1126/science.aaq0216 PMID: 29853680
67. Oppenlander RA. Food choice and sustainability: why buying local, eating less meat, and taking baby
steps won’t work. Minneapolis, MN: Langdon Street Press: Distributed by Itasca Books; 2013.
68. Francione GL, Charlton AE. Eat like you care: an examination of the morality of eating animals. 2015.
69. Mertens E, Van’T Veer P, Hiddink GJ, Steijns JM, Kuijsten A. Operationalising the health aspects of
sustainable diets: A review. Public Health Nutr. 2017; 20:739–57. https://doi.org/10.1017/
S1368980016002664 PMID: 27819199
70. Byrd-Bredbenner C, Grenci A, Quick V. Effect of a television programme on nutrition cognitions and
intended behaviours: Effect of a television programme. Nutr Diet. 2010 Aug 25; 67(3):143–9.
71. Macdiarmid JI, Douglas F, Campbell J. Eating like there’s no tomorrow: Public awareness of the envi-
ronmental impact of food and reluctance to eat less meat as part of a sustainable diet. Appetite. 2016;
96:487–93. https://doi.org/10.1016/j.appet.2015.10.011 PMID: 26476397
72. MacNair RM. The Psychology of Becoming a Vegetarian. Veg Nutr U K. 1998; 2(3):96–102.
73. Šedová I, Slovák Ľ, Ježková I. Coping with unpleasant knowledge: Meat eating among students of envi- ronmental studies. Appetite. 2016; 107:415–24. https://doi.org/10.1016/j.appet.2016.08.102 PMID:
27554181
74. Caviola L, Capraro V. Liking but Devaluing Animals: Emotional and Deliberative Paths to Speciesism.
2019;https://doi.org/10.31234/osf.io/sx5uw.
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 19 / 20
75. Bleidorn W, Hopwood CJ. Using machine learning to advance personality assessment and theory. Per-
sonal Soc Psychol Rev. 2019 May; 23(2):190–203.
76. Piazza J, Ruby MB, Loughnan S, Luong M, Kulik J, Watkins HM, et al. Rationalizing meat consumption.
The 4Ns. Appetite. 2015; 91:114–28. https://doi.org/10.1016/j.appet.2015.04.011 PMID: 25865663
77. Hopwood CJ, Bleidorn W. Psychological profiles of people who justify eating meat as natural, neces-
sary, normal, or nice. Food Qual Prefer. 2019; 75:10–4.
PLOS ONE Health, environmental, and animal rights motives for vegetarian eating
PLOS ONE | https://doi.org/10.1371/journal.pone.0230609 April 2, 2020 20 / 20
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