The impact of exercise training plus dietary interventions on ectopic fat in overweight/obese population with and without chronic disease: a systematic review, meta‐analysis, and meta-regression of randomized clinical trials

Abstract

Background The growing prevalence of obesity and related chronic diseases has led to increased interest in interventions targeting ectopic fat reduction to which its accumulation is linked to metabolic dysfunction. This study aimed to evaluate the effects of combined exercise training combined with dietary interventions compared to dietary interventions alone on ectopic fat (visceral fat area [VFA], liver fat, intramuscular fat [IMF], pancreatic fat, renal sinus fat, and pericardial and epicardial fats) in overweight and obese adults, both with and without chronic diseases. Methods Web of Science, Scopus, and PubMed were searched for original articles up to March 1, 2024, that included exercise versus control interventions on body weight and ectopic fat in adults with overweight or obesity. Weighted mean differences (WMD) for body weight, liver fat, pancreatic fat, and renal sinus fat and standardized mean differences (SMD) for VFA, IMF, pericardial and epicardial fats, and 95% confidence intervals (95% CI) were determined using random effects models. Results Thirty-two studies, including 1488 participants and 38 intervention groups, met the inclusion criteria. The combined intervention of exercise and diet did not reduce body weight [WMD=-0.23 kg, p=0.180], liver fat [WMD=0.05%, p=0.730], IMF [SMD=-0.08, p=0.640], pericardial and epicardial fats [SMD=-0.12, p=0.280], pancreatic fat [WMD=-0.24%, p=0.370], and renal sinus fat [WMD=0.01 cm2, p=0.170] when compared with a diet only group. Interestingly, exercise combined with diet significantly reduced VFA in participants with obesity [SMD=-0.12, p=0.040] and healthy males [SMD=-0.33, p=0.001] when compared with a diet only group. Conclusions The findings suggest that combined exercise and dietary interventions did not lead to significant reductions in most ectopic fat depots when compared to diet alone. However, a modest reduction in VFA was observed in participants with obesity and healthy males. These results highlight the nuanced impact of exercise in combination with dietary interventions and the need to consider specific fat depots and participant characteristics in obesity management strategies.