When A Diet Is Not Only About You
We have all been there: we begin a dietary shift for one reason or another, and inevitably, we find ourselves slipping back into old habits. This study attempted to answer a fundamental question about diets: how are some people better able to commit to a diet? Does it depend on the individual, the kind of diet, or is there something else going on?
In this exploratory study, participants were asked to categorize themselves into one of the following “restrictive diet” groups: vegetarian, vegan, paleo, gluten-free, or weight-loss. They were then asked about the extent to which they commit to their diet (or how often they have “cheated” in the recent past). They were also asked what they perceive makes it easier or harder for them to do so, as well as questions about themselves (predictors).
The researchers evaluated both subjective and measured adherence — how people felt they vs. how they actually acted — to the diet through questionnaires. Surprisingly the two were not strongly related, and for that reason the researchers carried on the analyses for the two separately. (For example, vegans scored higher on measured adherence than they self-reported, while the gluten-free group reported higher adherence than the researchers measured).
The researchers also examined predictors of adherence to diet: personality (self-control; emotional eating; and a variation of the Five-Factor Model), mental health (disordered eating behavior; and depression, anxiety, and stress symptoms), motivational factors (dietary motivation; moral foundations); social identification with dietary group, and self-efficacy (the belief that one has in their ability to handle different situations).
Lastly, participants were asked to answer an open-ended question about what they think makes it easier for them to stick to their diet (facilitators), and what makes it harder to do so.
The study shows that, on average, across all dietary groups, participants considered ethical concerns, their own health, and their level of conscientiousness as facilitators. Factors that made it harder were mostly inconvenience, and a lack of willpower.
Participants who stated they follow a vegan diet were more likely to stick to their eating pattern than participants following a vegetarian, paleo, or gluten-free diet (including participants with coeliac disease). The weight-loss group was least likely to stick to their diet.
Furthermore, vegans were most likely to mention ethical concerns and identity as factors that made it easier to adhere to their diet. They were the least likely group to mention conscientiousness, and weight-loss as facilitators. They were also the least likely to report experiencing difficulties in sticking to their diet, or lacking the willpower to do so. Finally, vegans had the highest levels of self-efficacy and social identification with their group than the other groups did.
In the final model, it was shown that the predictors of adherence overarching all diets were self-efficacy, and social identification. Weight-control and mood motivation (eating to feel better) were risk factors for adherence, again across all diets.
It appears that for vegans, diet was intertwined with their social identity and a feeling of group belonging, which empowered them to commit to their diet. The researchers suggest that “when a dietary pattern becomes a positive and meaningful part of one’s identity, adherence is no longer a chore […], instead it becomes an enactment of one’s values; an expression of the self”.
The low-adherence groups (weight-loss and paleo) indicated that their main motivation was their well-being, for which they relied on personal strength and restraint. Even though the weight-loss group stated that they use weight-loss as a motivation to diet, the results show that this might have a counterproductive effect.
One limitation of this broad, exploratory study, is that the sample was quite homogeneous: mostly young, relatively healthy, Caucasian women. This likely explains why demographics were not associated with any variation in diet adherence. This also means that we can be a bit skeptical about whether the same predictors of sticking to a diet would apply to a more diverse population. Furthermore, this study depended on participants’ honesty about their past eating behavior in the “measured” as well as “subjective” adherence, which is not necessarily reliable.
Nevertheless, the study made some first steps in examining whether self-efficacy, as well as considering this diet as part of our social identity could be the “secret” to why we stick to our diet more than others. Advocates working on dietary change models may want to consider these findings in their messaging.