A meta-analysis of 116 randomized clinical trials found that increased aerobic exercise duration correlated with greater reductions in body weight, waist circumference, and body fat measures in adults with overweight or obesity.

Researchers analyzed data from 6,880 participants. Each additional 30 minutes of weekly aerobic exercise was associated with a bodyweight reduction of 0.52 kg, a decreased waist circumference of 0.56 cm, and a lower body fat percentage of 0.37%. Nonlinear reductions were observed for waist circumference and body fat percentage at higher exercise durations.

At 150 minutes per week, participants averaged a weight loss of 2.79 kg, while at 300 minutes per week, weight loss increased to 4.19 kg, according to the results published in JAMA Network Open.

The study population comprised 4,199 female (61%) and 2,681 male (39%) participants with a mean age of 46 years and a mean BMI of 31. Geographic distribution included 48 trials in North America, 39 in Asia, 18 in Europe, 5 in Australia, 4 in South America, and 2 in Africa. Forty-one trials included participants with comorbidities such as type 2 diabetes, hypertension, or fatty liver disease, while 75 trials involved otherwise healthy participants.

Methodology and Implementation

Researchers analyzed data from PubMed, Scopus, Cochrane Central Register, and gray literature through April 30, 2024. The trials required a minimum 8-week intervention duration and supervised aerobic training. Seventy-eight trials implemented progressive aerobic training, while 38 used nonprogressive approaches. Weekly exercise duration ranged from 55 to 300 minutes, with a mean of 167 minutes (SD = 54). Adherence rates reached 80% or more in 48 trials, with dropout rates less than 20% in 80 trials and 20% or more in 27 trials.

Researchers highlighted heterogeneity among the trials, which may affect generalizability. Publication bias was identified for subcutaneous adipose tissue measures, and the ICEMAN tool was used to assess the credibility of key findings.

Secondary Outcomes

Visceral adipose tissue decreased by 1.60 cm², while subcutaneous adipose tissue reduced by 1.37 cm². Physical quality of life improved by 1.69 SD, and mental quality of life increased by 0.74 SD.

The intervention was associated with adverse events, primarily musculoskeletal symptoms, which were reported as mild to moderate, primarily musculoskeletal symptoms, with a relative risk of 1.74. The risk difference was 2 more events per 100 participants.

No significant reduction occurred in antidiabetic or antihypertensive medication use (risk difference: 1 more per 100 patients), though only 2 trials reported medication outcomes.

Quality Assessment

Fourteen trials demonstrated low risk of bias, 48 had some concerns, and 54 showed serious risk of bias. Evidence quality was rated high for waist circumference and visceral adipose tissue measures, moderate for body weight and body fat percentage, and low for quality-of-life measures and adverse events.

The study highlights the variability in methodologies and calls for standardization in future research to reduce heterogeneity and enhance the reliability of findings.

The authors declared having no competing interests.