Combined versus independent effects of exercise training and intermittent fasting on body composition and cardiometabolic health in adults: a systematic review and meta-analysis.

Mousa Khalafi, Michael E Symonds, Aref Habibi Maleki, Mohammad Hossein Sakhaei, Mahsa Ehsanifar, Sara K Rosenkranz

Journal: Nutrition journal 2024;23(1):7

PMID: 38183054

Free Full Text on BioMed Central View on PubMed

Plain Language Summary

Overweight and obesity are significant risk factors for non-communicable chronic diseases, including cardiovascular and metabolic conditions such as type 2 diabetes mellitus. Exercise training (Ex) and intermittent fasting (IF) have been shown to improve body composition and cardiometabolic health in overweight and obese adults. However, it remains unclear whether combining Ex and IF results in additive or synergistic effects. This study aimed to compare the combined effects of Ex and IF with standalone Ex or IF interventions in adults. Specifically, it investigated changes in body composition (e.g., body weight, body mass index, body fat, lean body mass, visceral fat, and waist circumference) and cardiometabolic health markers (e.g., fasting glucose, insulin, cholesterol levels, blood pressure, and VO₂ max/peak). This study was a systematic review and meta-analysis of eleven randomised controlled trials. Results showed that Ex plus IF led to greater reductions in body weight, body mass index, body fat, visceral fat, and waist circumference compared to Ex alone. However, changes in body composition and cardiometabolic health markers were not significantly different between Ex plus IF and IF alone, except for VO₂ max/peak. Authors concluded that the combination of Ex and IF promotes weight and fat loss, maintains muscle mass and increases cardiorespiratory fitness. However, a combination of Ex and IF is not associated with greater improvements in lipid profiles, glycemic markers, or blood pressure.

Abstract

INTRODUCTION AND AIM

Exercise training (Ex) and intermittent fasting (IF) are effective for improving body composition and cardiometabolic health overweight and obese adults, but whether combining Ex and IF induces additive or synergistic effects is less well established. We therefore, performed a systematic review and meta-analysis to compare the combined versus independent effects of Ex and IF on body composition and cardiometabolic health in adults.

METHOD

An electronic search was conducted in three main online databases including PubMed, Web of Science, and Scopus, from inception to March 9, 2023 for studies involving Ex plus IF trials versus standalone Ex and/or IF interventions in adults. Interventions had a duration of ≥ 2 weeks. Standardized (SMD) or weighted mean differences (WMD) and 95% confidence intervals were calculated in order to compare effects on body weight, body mass index (BMI), body fat lean body mass (LBM), visceral fat, and waist circumference. For cardiometabolic health, outcomes included fasting glucose, insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL), triglycerides (TG), high-density lipoprotein cholesterol (HDL), systolic (SBP) and diastolic (DBP) blood pressure, and VOmax/peak.

RESULTS

Ex plus IF decreased body weight [WMD: -3.03 kg (95% CI: -3.44 to -2.61), p = 0.001], BMI [WMD: -1.12 kg.m (95% CI: -1.28 to -0.95), p = 0.001], body fat [SMD: -0.72 (95% CI: -1.23 to -0.21), p = 0.005], visceral fat [SMD: -0.34 (95% CI: -0.63 to -0.05), p = 0.01], and waist circumference [WMD: -2.63 cm (95% CI: -4.16 to -1.11), p = 0.001] more than Ex alone. However, changes in body composition and cardiometabolic health markers were not significantly different for Ex plus IF when compared with IF alone, with the exception of VOmax/peak [SMD: 0.55 (95% CI: 0.14 to 0.97), p = 0.009].

CONCLUSION

We demonstrate that a combination of Ex and IF produces superior changes in body composition, but not in markers of cardiometabolic health when compared with Ex or IF alone. Ex plus IF could therefore be effective for weight and fat loss but has no additive or synergistic effects for other cardiometabolic health markers.

Address: Department of Physical Education and Sport Sciences, Faculty of Humanities, University of Kashan, Kashan, Iran. [email protected].; Centre for Perinatal Research, Academic Unit of Population and Lifespan Sciences, School of Medicine, University of Nottingham, Nottingham, NG7 2UH, UK.; Department of Exercise Physiology and Corrective Exercises, Faculty of Sport Sciences, Urmia University, Urmia, Iran.; Department of Exercise Physiology, Faculty of Sport Sciences, University of Guilan, Guilan, Iran.; Department of Kinesiology and Nutrition Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA.

DOI: 10.1186/s12937-023-00909-x