Effect of Carbohydrate-Restricted Dietary Patterns Based on Prescribed and Self-Reported Intake in Adults with Overweight and Obesity: A Systematic Review and Meta-Analysis

Background: Carbohydrate (CHO) restriction has regained attention as a dietary approach for weight management and cardiometabolic health, although evidence supporting its effectiveness remains controversial, particularly regarding degree of restriction. Objective: Examine effects of CHO-restricted vs higher CHO dietary approaches on weight- and cardiometabolic-related outcomes in adults with overweight or obesity without other established disease. Methods: Searches of MEDLINE, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases identified relevant randomized controlled trials published from 2010 to 2025. Primary outcomes were anthropometric outcomes (body weight, body mass index, waist circumference, and fat and lean body mass) and glycemic outcomes (fasting blood glucose and glycosylated hemoglobin levels). Meta-analyses were conducted using random-effects models for each outcome of interest. Heterogeneity was assessed using I2, evidence certainty using the Grading of Recommendations, Assessment, and Evaluation methodology, and publication bias was assessed using the Begg and Egger statistic and by generating funnel plots. Results: Twenty-three randomized controlled trials, represented in 28 articles, were included. Degree of CHO restriction varied across studies, with self-reported intake often less restrictive than prescribed levels. CHO restriction resulted in modest but significant reductions in body weight (mean difference [MD] –1.32 kg; 95% CI, –2.03 to –0.61), waist circumference (MD –0.89 cm; 95% CI, –1.44 to –0.34), and fat mass (standardized MD –0.29; 95% CI, –0.48 to –0.10) compared with higher CHO diets. CHO restriction reduced fasting blood glucose level (MD –0.08 mmol/L; 95% CI, –0.17 to 0.00) (to convert to mg/dL, multiply by 18.0), glycated hemoglobin concentration (MD –0.16%; 95% CI, –0.28% to –0.04%), triglyceride level (MD –0.17 mmol/L; 95% CI, –0.26 to –0.08) (to convert to mg/dL, multiply by 88.6), and systolic blood pressure (MD –4.86 mm Hg; 95% CI, –6.60 to –3.11). Conclusions: CHO restriction (<45% total daily energy intake) likely provides modest benefits for weight management and certain cardiometabolic risk factors in adults with overweight or obesity.