Nutritional intervention strategies for the management of overweight and obesity in primary health care: A systematic review with meta-analysis.

A systematic review with meta-analysis (MA) was conducted to synthesize the effectiveness of nutrition intervention strategies for managing overweight and obesity in the adult population attending primary health care. Relevant articles were searched in the PubMed, Embase, Web of Science, Cochrane and LILACS databases from inception to January 2020. Seventy studies were identified: 45 randomized controlled trials (RCTs) and 25 uncontrolled before-after studies (UBAs). The MA of nutritional intervention revealed a reduced average estimate of the effect on weight in RCTs (weighted mean differences [WMD] = -1.80 kg, 95% confidence interval [CI], -2.40 to -1.19), BMI (WMD = -0.80 kg/m , 95% CI, -1.11 to -0.49), and WC (WMD = -2.28 cm, 95% CI, -3.06 to -1.49); and for UBAs showed reductions in weight (WMD = -4.17 kg; 95% CI, -5.18 to -1.70), BMI (WMD = -1.26 kg/m ; 95% CI, -1.81 to -0.72) and (WMD = -2.90 cm; 95%CI, -4.21 to -1.59). There was no association between treatment effect and follow-up for both designs. Nutritional interventions alone yielded a higher but nonsignificant average reduction on weight when compared with combined components intervention. Interventions delivered through individual or group sessions showed a similar positive effect on weight decrease. The dietary prescription approach yielded a greater effect on weight loss than did the behavioural approaches but only in UBA studies.