Effects of Different Exercises Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and network meta-analysis of randomized controlled trials
PubMed 39275322 · doi:10.3390/nu16173007
What was done
Authors conducted a systematic review and network meta-analysis searching PubMed, Web of Science, Embase, and Cochrane Library through May 2024 (PROSPERO CRD42024542184). They included randomized controlled trials of healthy adults aged 18 to 65 years comparing four combined interventions: exercise with calorie restriction (CR+EX), exercise with time-restricted eating (TRF+EX), exercise with 5/2 intermittent fasting (5/2F+EX), and exercise with a ketogenic diet (KD+EX). Risk of bias was evaluated using the Cochrane risk of bias tool, and intervention efficacy was ranked using Surface Under the Cumulative Ranking (SUCRA) curves across body composition outcomes.
What was found
The review included 78 randomized controlled trials with 5,219 participants. For weight reduction, CR+EX ranked highest (CR+EX > KD+EX > TRF+EX > 5/2F+EX); relative to CR+EX, effect sizes were 2.94 (95% CI: -3.64, 9.52) for 5/2F+EX, 2.37 (-0.40, 5.15) for TRF+EX, and 1.80 (-1.75, 5.34) for KD+EX. For BMI, CR+EX ranked highest (CR+EX > KD+EX > 5/2F+EX > TRF+EX); relative to CR+EX, effect sizes were 1.95 (-0.49, 4.39) for 5/2F+EX, 2.20 (1.08, 3.32) for TRF+EX, and 1.23 (-0.26, 2.71) for KD+EX. For body fat percentage, CR+EX ranked highest (CR+EX > 5/2F+EX > TRF+EX > KD+EX); relative to CR+EX, effect sizes were 2.66 (-1.56, 6.89) for 5/2F+EX, 2.84 (0.56, 5.13) for TRF+EX, and 3.14 (0.52, 5.75) for KD+EX. For lean body mass in males, CR+EX ranked highest (CR+EX > TRF+EX > KD+EX); relative to CR+EX, effect sizes were -1.60 (-6.98, 3.78) for TRF+EX and -2.76 (-7.93, 2.40) for KD+EX. For lean body mass in females, TRF+EX ranked highest (TRF+EX > CR+EX > 5/2F+EX > KD+EX); relative to TRF+EX, effect sizes were -0.52 (-2.58, 1.55) for CR+EX, -1.83 (-4.71, 1.04) for 5/2F+EX, and -2.46 (-5.69, 0.76) for KD+EX.
Why it matters
This network meta-analysis establishes a comparative hierarchy among popular diet-exercise combinations, showing that traditional calorie restriction with exercise generally yields superior weight and fat loss compared to ketogenic or intermittent fasting regimens, while time-restricted feeding may better preserve lean mass in females.
Limits
Many relative effect size estimates had wide confidence intervals spanning zero, indicating substantial statistical imprecision in pairwise network comparisons. The abstract combines different exercise modalities (aerobic, resistance, mixed) under broad combined categories, limiting granularity regarding specific exercise types. Findings are limited to healthy adults aged 18 to 65 and cannot be generalized to populations with metabolic disease or older adults. Intervention duration, dietary compliance, and specific macronutrient details were not reported in the abstract.
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