The Effect of Aerobic or Resistance Exercise Combined With a Low-Calorie Diet Versus Diet Alone on Cardiometabolic Outcomes in Adults with Overweight and Obesity: A Systematic Review and Meta-Analysis

CONTEXT: Individual studies examining the combined effects of exercise and a low-calorie diet on cardiometabolic factors have yielded inconsistent results. OBJECTIVE: In this systematic review and meta-analysis of randomized controlled trials we aimed to determine whether adding exercise to a low-calorie diet has impacts on glucose homeostasis, lipid profiles, and blood pressure in adults with overweight and obesity. DATA SOURCES: We searched the PubMed/MEDLINE, EMBASE, Web of Sciences, and Scopus databases from their inception to August 2024 to identify trials comparing the effects of exercise plus diet versus a low-calorie diet on cardiometabolic factors in adults with overweight and obesity. DATA EXTRACTION: Six reviewers independently performed title/abstract screening, data extraction, and quality assessment in duplicate. Meta-analyses were conducted using random-effects models to calculate summary estimates. DATA ANALYSIS: Ninety-seven eligible studies were included. Our findings demonstrated that incorporating exercise into a weight-loss diet significantly improved serum glucose, insulin levels, homeostatic model of insulin resistance, triglycerides, high-density lipoprotein cholesterol, and both systolic and diastolic blood pressure compared to diet alone. The analysis results highlighted the primary association of these benefits with aerobic exercise, rather than resistance training or combined aerobic and resistance exercises. Most improvements in cardiovascular risk factors were observed in supervised, high-intensity exercise programs, particularly cycling. The combination of aerobic exercise and a weight-loss diet was especially effective for metabolically healthy obese individuals. CONCLUSION: The moderate to low certainty of evidence found in this review suggests that to mitigate metabolic risk in individuals with overweight or obesity, dietary intervention combined with high-intensity aerobic exercise, particularly cycling, may offer greater benefits than resistance training. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number: CRD42020173434.