Plain language summary
Being overweight or obese is a huge risk factor for many detrimental conditions. It is estimated that around one-third of the world’s population will be overweight or obese by 2025. Hence there is a need to look at dietary strategies in the prevention and treatment of overweight and obesity. Plant-based diets have always existed, however interest in the topic has increased recently and more research is being done on the health-related effects of different plant-based diets. There are many reasons why someone might convert to a plant-based diet, possible health benefits such as weight management are among the most common. The purpose of this review was to evaluate intervention studies assessing the effects of different plant-based diets on body mass index and weight. The results suggest that plant-based diets may improve weight status in some patient groups. It should be noted that only one study out of the 19 included in the review had normal weight, clinically healthy participants. The study populations for the rest were overweight, obese or had type 2 diabetes. Future research should aim to include a representative study population and apply study diets without dietary restrictions.
There is an increasing number of people who convert to a plant-based diet. The desire for health benefits, including weight management, is often a contributing factor behind this dietary choice. The purpose of this review was to evaluate intervention studies assessing the effects of different plant-based diets on body mass index and weight. A literature search was conducted in PubMed until December 2019. Twenty-two publications from 19 studies were included. The majority of them were randomized controlled trials comparing a low-fat vegan diet to an omnivore diet in participants with overweight, type 2 diabetes mellitus and/or cardiovascular disease. All studies reported weight reductions, of which seven revealed significant differences, and four revealed non-significant differences between the intervention and the control groups. The results suggest that plant-based diets may improve weight status in some patient groups. Due to restrictions in fat intake in many studies, followed by reduced energy intake, the effects of the different interventions differ depending on the specific plant-based diets investigated. Future research should aim to include a representative study population and apply study diets without dietary restrictions.