A 12-week vegan diet can lead to significant weight loss and improved blood sugar control in overweight adults and individuals with type 2 diabetes, according to a meta-analysis of 11 randomized trials.
The study, which involved nearly 800 participants, was presented at the European Congress on Obesity (ECO) in Maastricht, Netherlands.
The research team, led by Anne-Ditte Termannsen from the Steno Diabetes Center Copenhagen, Denmark, found no effect of the vegan diet on blood pressure or triglycerides.
Study Methodology
The researchers carried out a systematic review and meta-analysis of all relevant English language randomized trials published up to March 2022.
They compared the effect of vegan diets to other types of diets on cardiometabolic risk factors such as body weight, BMI, blood sugar levels, blood pressure, cholesterol levels, and triglycerides.
Vegan diets were compared with either passive control groups (participants continuing their normal diet) or active control groups (participants following other dietary interventions).
Findings of the Study
Data from 11 studies involving 796 individuals (average age ranging from 48 to 61 years) with overweight or type 2 diabetes were analyzed. Trials lasted for at least 12 weeks and considered weight loss of at least 5 kg clinically meaningful.
Compared to control diets, vegan diets significantly reduced body weight (average effect -4.1 kg) and BMI (-1.38 kg/m2).
However, effects on blood sugar level (-0.18 %-points), total cholesterol (-0.30 mmol/L), and low-density lipoprotein cholesterol (-0.24 mmol/L) were relatively small.
The researchers observed greater reductions in body weight and BMI when vegan diets were compared with continuing a normal diet without dietary changes, than compared with other intervention diets.
Implications of the Study
Termannsen suggests that this study provides reasonable certainty that adhering to a vegan diet for at least 12 weeks can lead to significant weight loss and improved blood sugar levels, making it a viable management strategy for overweight and type 2 diabetes.
Vegan diets likely lead to weight loss due to reduced calorie intake, owing to a lower fat content and higher dietary fiber content. However, further evidence is needed regarding other cardiometabolic outcomes.
Caveats to the Findings
The researchers note several limitations to their findings, including the small sample sizes of most studies, and the substantial variation in the vegan diets in terms of carbohydrate, protein, and fat content.
They caution that the effects of vegan interventions on cardiometabolic health could be partially caused by differences in macronutrient composition and energy intake between the groups.
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