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.

OBJECTIVES: It was estimated that approximately 60% of the world's population is classified as inactive or insufficiently active. This meta-analysis investigated the effect of web-based interventions on different types of physical activity (PA) measurements in general population and potential moderating variables. STUDY DESIGN: PubMed, CINAHL, EBSCOhost, PsycINFO, Scopus, Ovid, and ScienceDirect literature searches were conducted to identify studies investigating the effect of web-based interventions on PA. METHODS: Randomized controlled trials on PA changes reported in moderate to vigorous intensity, walking, and step count in the intervention group in comparison with the control group were pooled with a fixed-effects model separately. RESULTS: A total of 22 studies comprising 16,476 and 14,475 subjects in intervention and control groups respectively were included. Web-based interventions had positive and significant effect on increasing PA. Of 14 trials reporting moderate to vigorous physical activity (MVPA), five showed a significant increase in the MVPA level after the intervention. There was significant heterogeneity between studies (P < 0.001 and I2 = 67.8%). Of six trials that reported the number of steps by using the pedometer, three showed a significant increase for the step counts in intervention groups (P < 0.001 and I2 = 93.3%), of 14 trials assessed PA level by reporting walking minutes per week, four studies showed a significant increase in walking minutes. There was significant heterogeneity between studies (P < 0.001, I2 = 68.1%). Overall, the effect of web-based interventions seemed to be influenced by the characteristics of mean age of participants, trial duration, and study quality (P < 0.05). CONCLUSION: The web-based PA interventions had a positive significant effect on increasing all the three types of PA among the general population. However, the effects appear to depend on the design of the study, age, and duration of studies