Purpose This study aimed at quantifying and ranking the effects of different foods or food groups on weight loss. Methods We searched PubMed, Scopus, Cochrane Central Register of Controlled Trials, and Embase to April 2021. We included randomized trials evaluating the comparative effects of two or more food groups, or compared a food group against a control group (usual diet, no intervention) for weight loss in adults. We conducted random-effects network meta-analysis with Bayesian framework to estimate mean difference [MD] and 95% credible interval [CrI] of the effect of food groups on weight loss. Results 152 RCTs with 9669 participants were eligible. Increased consumption of fish (MD - 0.85 kg, 95% CrI - 1.66, - 0.02; GRADE = low), whole grains (MD - 0.44 kg, 95% CrI - 0.88, 0.0; GRADE = very low), and nuts (MD - 0.37 kg, 95% CI - 0.72, - 0.01; GRADE = low) demonstrated trivial weight loss, well below minimal clinically important threshold (3.9 kg), when compared with the control group. Interventions with other food groups led to no weight loss when compared with either the control group or other food groups. The certainty of the evidence was rated low to very low with the point estimates for all comparisons less than 1 kg. None of the food groups showed an important reduction in body weight when restricted to studies conducted in participants with overweight or obesity. Conclusions Interventions with a single food or food group resulted in no or trivial weight loss, especially in individuals with overweight or obesity. Further trials on single foods or food groups for weight loss should be highly discouraged.

A systematic review was conducted of randomized trials of workplace weight management interventions, including trials with dietary, physical activity, environmental, behavioral, and incentive-based components. Main outcomes were defined as change in weight-related measures. Keywords related to weight management and workplace interventions were used to search relevant databases, and 23 eligible studies were reviewed in detail using a data extraction form and quality assessment checklist. The trials were conducted mainly in the USA and Europe, with four additional countries represented. Interventions were mostly multicomponent and were implemented in both sexes and in a range of employment categories. Intervention effectiveness appeared unrelated to region of the world and was highest in 6-12-month trials. The results ranged widely from clinically significant 8.8-kg weight loss in one trial to less effective than the control treatment in others. Some workplace interventions achieve clinically significant benefits, and further studies are needed to replicate those results in wider sociocultural and geographical contexts.