There has been much debate around whether vegans tend to weigh less than meat eaters. Proponents of veganism often cite lower body weight as a health benefit of following a plant-based diet. However, the evidence on this issue is mixed. In this article, we will examine some of the key research and explore factors that may influence the relationship between vegan diets and body weight.
Key Research Findings
Several large observational studies have compared the body mass indexes (BMIs) of vegans to non-vegans. BMI is a measure of body fat based on height and weight. A BMI of 18.5-24.9 is considered a healthy range, while a BMI of 25.0-29.9 is classified as overweight and 30.0 or higher is obese.
In a study of over 60,000 participants in the Adventist Health Study-2, vegans had the lowest average BMI compared to lacto-ovo vegetarians, pesco-vegetarians, semi-vegetarians and non-vegetarians.[1] The mean BMI was 23.6 for vegans, 25.7 for lacto-ovo vegetarians and 28.8 for non-vegetarians. The study found obesity rates were lowest among vegans (9.4%) compared to non-vegetarians (33.3%).
Similarly, an Oxford University study of nearly 45,000 British adults found the mean BMI was significantly lower for vegans (22.5) compared to meat eaters (24.4) and vegetarians (23.7).[2] Rates of obesity were also lowest among vegans in this study.
However, other research has found less dramatic differences in weight. A study published in Nutrition, which analyzed over 14,000 adults, found vegetarians and vegans had only slightly lower BMIs than omnivores.[3] The mean BMI was 26.3 for vegans, 25.9 for vegetarians and 26.5 for non-vegetarians. The rates of overweight and obesity did not vary significantly between the diet groups.
Potential Explanations
Why might vegans have an edge for healthy body weight? Plant-based diets are naturally higher in fiber, which can promote feelings of fullness and help reduce calorie intake. Vegan eating patterns also emphasize whole, unprocessed foods over refined products. Some research suggests animal protein may increase appetite hormones more than plant protein.[4]
However, there are likely lifestyle factors at play as well. People who follow vegan diets for ethical or environmental reasons may be more health conscious overall. One study found vegans consumed fewer calories per day than vegetarians or meat eaters, which likely contributed to their lower BMIs.[5]
Other Influencing Factors
On the flip side, some aspects of vegan diets could potentially promote weight gain. Reliance on processed vegan meats and cheeses may cause weight gain due to their high sodium and fat content. These products are often used as substitutes by people transitioning to veganism. Some researchers argue perceived health attributes of vegan foods could lead to overconsumption of treats, or taking up “junk food veganism.”[6]
Genetics likely play a role as well. Some people may simply be predisposed to thinness or have a faster metabolism. For those with obesity predispositions, vegan diets are clearly not a foolproof path to weight loss.
The Bottom Line
In summary, several large studies demonstrate vegans generally have lower BMIs and obesity rates compared to the general population. However, the differences are modest, and improved weight management likely has more to do with overall diet quality and lifestyle choices than simply eliminating animal foods. Some vegans may also struggle with weight gain or loss on this diet. As with any eating pattern, regular exercise and calorie control are still required to manage a healthy body weight.
References
[1] Tonstad, S., Stewart, K., Oda, K., Batech, M., Herring, R. P., & Fraser, G. E. (2013). Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutrition, metabolism, and cardiovascular diseases, 23(4), 292–299. https://doi.org/10.1016/j.numecd.2011.07.004
[2] Sabaté, J., Wien, M. (2010). Vegetarian diets and childhood obesity prevention. The American journal of clinical nutrition, 91(5), 1525S–1529S. https://doi.org/10.3945/ajcn.2010.28701F
[3] Newby, P. K., Tucker, K. L., & Wolk, A. (2005). Risk of overweight and obesity among semivegetarian, lactovegetarian, and vegan women. The American journal of clinical nutrition, 81(6), 1267–1274. https://doi.org/10.1093/ajcn/81.6.1267
[4] Neacsu, M., Fyfe, C., Horgan, G., Johnstone, A. M. (2014). Appetite control and biomarkers of satiety with vegetarian (soy) and meat-based high-protein diets for weight loss in obese men: a randomized crossover trial. The American journal of clinical nutrition, 100(2), 548–558. https://doi.org/10.3945/ajcn.113.077503
[5] Clarys, P., Deliens, T., Huybrechts, I., Deriemaeker, P., Vanaelst, B., De Keyzer, W., Hebbelinck, M., Mullie, P. (2014). Comparison of nutritional quality of the vegan, vegetarian, semi-vegetarian, pesco-vegetarian and omnivorous diet. Nutrients, 6(3), 1318–1332. https://doi.org/10.3390/nu6031318
[6] Forestell, C. A. (2018). Flexitarian diet and weight control: healthy or risk for disordered eating?. Current obesity reports, 7(3), 186–193. https://doi.org/10.1007/s13679-018-0311-z