Vegetarian diet is associated with a loss of 3.4 kg (or 4.6 kg depending on the type of data analysis).
Vegetarians are often leaner than omnivores, which could push people looking to slim to opt for the scheme. According to a meta-analysis published in the Journal of the Academy of Nutrition and Dietetics, being a vegetarian helps indeed to lose a few kilos.
Vegetarian diets (without meat) and vegan (no animal products: no meat, eggs or milk or honey …) have many benefits for cardiovascular health, blood pressure or diabetes. This is one reason why more and more people are interested in these schemes, even if they are sometimes difficult to keep over time.
To find out if vegetarian and vegan diets allow to lose weight and how exactly, US and Japanese researchers conducted a systematic literature review and meta-analysis on this topic. They searched clinical trials with adults, which lasted at least four weeks, and identified 15 clinical trials with 17 intervention groups, including 4 with witnesses.
Results: by switching to a vegetarian (or vegan), people lost an average of 3.4 kg in an analysis by “intention to treat”. Indeed, in a clinical trial, some patients do not properly follow the protocol, and may be excluded from the results. In an analysis by intention to treat all patients are taken into account, even if they did not follow the protocol correctly, allowing more stick to reality where patients can track their ill-treatment.
In another analysis, removing missing values (for example by not taking account of patients who dropped out along the way), weight loss reached 4.6 kg. There was no significant difference in weight loss between the lacto-ovo-vegetarian diets (with milk and eggs) and vegans(vegetarian).
In addition, the researchers observed a greater weight loss when starting weight was higher, when there were fewer women, the participants were older and longer. The authors stress that the studies remain relatively few and of variable quality.
To explain the weight loss associated with these diets, the researchers suggest the high fiber content, low in fat content (even if the fat content of the studied diets varied widely: from 9% to over 30%) and better Energetic cost.
In conclusion, becoming vegetarian or vegan can be a good choice for line and health. However, it must ensure adequate intake of vitamin B-12, which may be provided by food supplements.