A low-fat, plant-based diet may contribute to more significant weight loss over a shorter period than popular weight-loss injections like Ozempic, according to research by U.S. scientists. The study found that participants who adopted a vegan diet lost an average of 13 pounds in four months, while trials indicate that individuals using semaglutide, the active ingredient in Ozempic and Wegovy, lose approximately a stone (about 14 pounds) over nine months.
Some studies on semaglutide show an even slower weight loss rate, with patients losing about 10 pounds over seven months. The new research, published in JAMA Network Open, involved 224 overweight adults, predominantly women, with an average age of 54. Participants were divided into two groups: one adopting a low-fat vegan diet and the other maintaining their usual eating habits.
Those on the vegan diet were permitted to consume unlimited amounts of fruits, vegetables, grains, and legumes but were instructed to avoid meat, fish, dairy, and eggs. After 16 weeks, this group increased their vegetable intake by about 150 grams and fruit intake by approximately 80 grams. Consumption of legumes nearly tripled, and intake of plant-based meat alternatives more than doubled.
The researchers noted that a key factor in the weight loss was the reduced energy density of plant-based foods. While the vegan participants consumed a similar volume of food as before, their daily calorie intake decreased by about 500 calories, from an average of 1,834 to 1,343. This reduction represents a decrease of more than a quarter in daily caloric intake. Plant-based foods are high in water and fiber and low in fat, which increases satiety without a proportional rise in energy content, thereby reducing calorie intake without deliberate restriction.
Beyond weight loss, the study observed that participants on the vegan diet experienced more stable blood sugar levels, reduced fat in the liver and muscles, and increased calorie expenditure during food digestion. The study's authors suggested that dietary composition, particularly an emphasis on plant foods, can significantly influence energy intake regulation, leading to weight loss and metabolic improvements.
The scientists acknowledged certain limitations, including reliance on self-reported food consumption and the fact that participants volunteered for the study, which might affect the generalizability of the findings to the wider population.
Approximately 3.5 million people in the UK follow a plant-based diet. While such diets are associated with health benefits, including a lower risk of heart disease, diabetes, and cancer, experts also highlight potential risks such as vitamin deficiencies. Vitamin B12, crucial for blood vessel and brain function, is notably absent in plant-based foods and is primarily found in animal products. The NHS advises vegans to take a daily B12 supplement to avoid potential neurological symptoms like anxiety, depression, and psychosis that can arise from deficiency.