The researchers analyzed data from 29 studies involving 20 randomized clinical trials spanning 22 years with 1,878 participants. They found that the results for the plant-based participants were consistently positive.
Weight loss was most pronounced in those at high risk of cardiovascular disease (loss of 3.6 kg), followed by those with type 2 diabetes (loss of 2.8 kg). An unexpected signal was observed in studies of calorie restriction versus non-restriction, with non-calorie-restricted plant-based people losing more than half the weight (1.8 kg) compared to restricted plant-based people (4.7 kg).
However, not all plant-based diets are created equal. For example, plant-based meals at fast food restaurants may contain high-calorie, refined carbohydrates, hydrogenated oils, high-fructose corn syrup, sucrose or artificial sweeteners, and salt.
Although it was not possible to control for the wide range of diets included in this meta-analysis, from vegan to lacto-ovo-vegetarian (including eggs and dairy products), the overall signal from these diverse plant-based diets was clear. Plant-based diets may have a synergistic (or at least non-antagonistic) effect that could enhance the effectiveness of optimal medical therapy in the prevention and treatment of a range of cardiometabolic diseases.