# Synergistic Effects of Combined Diet and Exercise on Body Composition in Adults: A Systematic Review and Meta-Analysis

## TL;DR

Combining diet and exercise leads to better body composition improvements in adults compared to using either method alone.

## Contribution

This study provides the first comprehensive meta-analysis comparing combined, diet-only, and exercise-only interventions for body composition in adults.

## Key findings

- Combined interventions significantly reduced BMI and body fat percentage.
- Total body water increased significantly with combined interventions.
- Exercise-only and diet-only approaches had limited effects on muscle mass and TBW.

## Abstract

Obesity and poor body composition are major contributors to chronic disease risk inadults. This review aimed to compare the effectiveness of exercise-only, diet-only, and combined interventions in improving body composition outcomes.

A systematic review and meta-analysis were conducted based on Judies published between 2016 and 2024 from Scopus, Web of Science, and ScienceDirect. Forty-six Judies involving 3,429 adults across five continents met inclusion criteria. Quality appraisal followed PRISMA and MMAT guidelines. A meta-analysis using RevMan 5.4 included six eligible Judies.

Combined interventions resulted in the most consistent improvements in body mass index (BMI) (SMD, -1.74; 95 % CI: -3.07 to -0.40; P = .01 ), body fat percentage (%BF) (SMD, -2.40; 95 % CI: -2.91 to -1.88; P < .00001), and total body water (TBW) (SMD, 1.54; 95 % CI: 1.04 to 2.04; P < .00001). Exercise-only and diet-only approaches also improved BMI and fat mass but had limited effects on muscle mass and TBW.

Integrated interventions combining physical activity and dietary changes are more effective than single-modality strategies. Programs of at least 12 weeks with supervision and cultural adaptation are recommended for optimal improvements in adult body composition.

This Systematic review is registered at PROSPERO (Reference number: CRD420251020596).