A 12-week vegetarian diet can lead to clinically meaningful weight loss and improve blood sugar control in overweight adults and patients with type 2 diabetes, according to a meta-analysis of 11 randomized trials involving nearly 800 participants (18 years and older) in Maastricht. , presented at this year’s European Congress on Obesity (ECO) in the Netherlands (4–7 May). The study is by Anne-Dette Termansen and colleagues at the Steno Diabetes Center in Copenhagen, Denmark.
However, a vegetarian diet rich in fruits, vegetables, nuts, legumes and seeds, with the exception of all animal-derived foods, did not affect blood pressure or triglycerides (a type of fat in the blood) compared to other diets.
For this study, researchers conducted a systematic review and meta-analysis of all relevant English-language randomized trials published through March 2022, comparing the effects of a vegetarian diet with other types of diet on cardiometabolic risk factors — body weight, body mass index. [BMI]Blood sugar levels, systolic and diastolic blood pressure, total cholesterol, low-density lipoprotein cholesterol (so-called ‘bad cholesterol’), high-density lipoprotein cholesterol and triglycerides.
The vegan diet was compared with either a passive control group (participants continuing a normal diet without any dietary changes) or an active control group (following other dietary interventions such as the Mediterranean diet, various diabetes diets or portion-controlled diets).
Data were analyzed for 11 studies involving 796 individuals (mean age ranged from 48 to 61 years) with overweight (25 kg/m BMI).2 or more) or type 2 diabetes. Trials lasted at least 12 weeks (median duration 19 weeks) and a weight loss of at least 5 kg (11 lb) was considered clinically meaningful.
Analysis showed that compared to the control diet, vegetarian diets significantly reduced body weight (effect mean -4.1 kg) and BMI (-1.38 kg/m).2) but the effects on blood sugar levels (-0.18%-points), total cholesterol (-0.30 mmol/L) and low-density lipoprotein cholesterol (-0.24 mmol/L) were relatively small.
Further analysis revealed greater reductions in body weight and BMI when vegetarian diets were compared with normal diets without dietary modification (-7.4 kg and -2.78 kg/m2 respectively), compared to other intervention diets (-2.7 kg and -0.87 kg/m2)
“This rigorous evaluation of the best evidence available to date indicates with reasonable certainty that adherence to a vegetarian diet for at least 12 weeks can produce clinically meaningful weight loss and improve blood sugar levels, and therefore can be used to control overweight and type 2 diabetes, Termansen said. “Vegan diets likely lead to weight loss because they are associated with lower caloric intake due to lower amounts of fat and higher amounts of dietary fiber. However, more evidence is needed regarding other cardiometabolic outcomes.”
The researchers note several caveats to their findings, including that most studies had small sample sizes and that vegetarian diets varied considerably by carbohydrate, protein, and fat content, and that none of the studies specified a control diet that exactly matched the intervention. All other aspects of the diet except veganism. Therefore, the effect of the vegetarian intervention on cardiometabolic health may be partially due to differences in macronutrient composition and energy intake between groups.