A low-fat plant-based diet may lead to greater weight loss than Ozempic, the medication whose active ingredient is semaglutide, researchers have found. A study indicated that individuals following a vegan diet lost an average of 5.9 kilograms (approximately 13 pounds) over 16 weeks, a figure that exceeds the weight loss observed in some trials of semaglutide.
Previous research on semaglutide has shown varying results. A 2017 study in The Lancet Diabetes and Endocrinology journal reported that patients taking a 0.5mg semaglutide injection lost about 3.7kg (around 8lb) over 30 weeks, while those on a 1mg dose lost approximately 4.5kg (nearly 10lb) in the same period. A separate 2021 study in the same journal found that participants on the highest dose of 2mg lost about 6.9kg (just over a stone) after 40 weeks.
The vegan diet study, originally conducted in 2020, involved 224 overweight adults, predominantly women with an average age of 54. Participants were divided into two groups: one adopted a low-fat plant-based diet, while the other maintained their usual eating habits. Those on the vegan diet were permitted to consume unlimited fruits, vegetables, grains, and legumes but were instructed to avoid meat, fish, dairy, and eggs.
After 16 weeks, the vegan diet group significantly reduced their meat and dairy intake, consuming around 1g per day, and eliminated egg consumption almost entirely. Concurrently, their intake of vegetables increased by approximately 150g, fruit intake rose by about 80g, legume consumption nearly tripled, and their consumption of plant-based meat alternatives more than doubled.
A secondary analysis of the original research sought to explain these results. Researchers discovered that individuals on the vegan diet were consuming nearly 500 fewer calories daily compared to those who continued to eat meat, dairy, fish, and eggs. Their daily calorie intake dropped from an average of 1,834 to 1,343 calories, a decrease of more than a quarter. The study authors noted that plant-based foods are high in water and fiber and low in fat, which increases food volume without a proportional increase in energy content, thereby promoting satiety and reducing energy intake without deliberate caloric restriction.
Beyond weight loss, the initial study also found that participants on the vegan diet demonstrated improved blood sugar control, reduced liver and muscle fat, and burned more calories during food digestion. The new analysis suggests that dietary composition, particularly an emphasis on plant foods, can significantly influence energy intake regulation, contributing to both weight loss and metabolic improvements.
While the findings are promising, the researchers acknowledged certain limitations. The study relied on self-reported food consumption, and the participants volunteered, meaning they may not be representative of the general population. Approximately 3.5 million people in the UK currently follow a plant-based diet. Experts suggest plant-based diets offer various health benefits, with separate studies indicating lower risks of heart disease, diabetes, and cancer among vegans compared to meat-eaters. However, concerns exist regarding potential vitamin deficiencies, particularly vitamin B12, which is not naturally found in plant-based foods and is crucial for nerve function. The NHS advises vegans to take a daily vitamin B12 supplement to avoid potential neurological symptoms.