Experts at the University of Navarra have been assessing the benefits of “pro-vegetarian diets”, rich in vegetables, fruit and grains.
Plenty of studies have suggested these diets can have a protective role in relation to cardiovascular disease and diabetes, but much less is known about how they affect people’s chances of becoming obese.
The team has therefore been examining the association between varying degrees of pro-vegetarian diet and the incidence of obesity (body mass index in excess of 30).
Some 16,000 healthy, non-obese adults were tracked from 1999 for an average of 10 years. Participants completed detailed food questionnaires at the start of the study, and a pro-vegetarian diet index (PVI) was used to score each person on the types of food they ate.
Points were given for eating seven plant food groups: vegetables, fruits, grains, nuts, olive oil, legumes (such as peas, beans and lentils) and potatoes. Points were subtracted for five animal groups: animal fats, dairy, eggs, fish and other seafood, and meat.
Based on their scores, participants were categorised into five groups – from the 20% with the least pro-vegetarian diet (group one) to the 20% with the most (group five).
Meaty obesity levels
In all, 584 participants became obese. Modelling showed that, compared to the least-vegetarian participants in group one, the most vegetarian (group five) were 43% less likely to become obese.
In groups two, three and four the reduced risk of obesity, compared to group one, was 6%, 15% and 17% respectively.
The results held true irrespective of other influential factors including sex, age, alcohol intake, BMI, family history of obesity, snacking between meals, smoking, sleep duration and physical activity.
The research, which has yet to be published, is limited by the fact that it shows observational differences rather than evidence of cause and effect, the team acknowledged. However, it supports current recommendations to follow plant-rich diets with less meat and animal products.
“Our study suggests that plant-based diets are associated with substantially lower risk of developing obesity,” the authors explained in an abstract presented at the recent European Congress on Obesity in Porto, Portugal.
Academics at the University of Oxford last year estimated that if the world went vegetarian, 7.3 million deaths would be avoided – half of which would be down to a combination of increased fruit and vegetable consumption and reduced calorie intake, leading to fewer people being overweight or obese.
The researchers, from the Oxford Martin Programme on the Future of Food, said they didn’t expect everyone to become vegetarian or vegan, but the benefits of shifting diets were considerable, socially, environmentally and economically, they argued.
Professor Maira Bes-Rostrollo, who is leading the research at the University of Navarra, also suggested a “gradual and gentle” approach is required to shift people to more plant-based diets.