Physical Activity for Obesity in Adolescents: Effects on Weight and Body Fat

Based on an evidence synthesis current to December 2025, engaging in physical activity can lead to minor decreases in body fat percentage, waist circumference, and total body weight among teenagers with obesity when contrasted with a lack of exercise.

Researchers analyzed data from 30 studies involving 1,508 participants, highlighting the need for larger, longer-lasting, and better-quality studies.

Globally, obesity amongst adolescents (aged 10 to 19 years) has tripled since 1990, with projections indicating over 300 million children and adolescents may be living with obesity by 2050. Childhood and adolescent obesity can have adverse effects on both mental and physical well-being, potentially elevating the likelihood of developing kidney disease, liver disease, or cancer during adulthood. Weight loss is the best way to reduce the health risks caused by obesity. This is usually done through lifestyle changes such as doing more physical activity and eating healthier foods, or with surgery or medication.

In Plain English: The Clinical Takeaway

• Modest Anthropometric Changes: Engaging in physical activity—ranging from aerobic exercise to active video gaming—leads to small average reductions in body weight (1.88 kg), waist size (2.88 cm), and body fat percentage (2.96%).
• Clinical Uncertainties Remain: Current data does not offer definitive proof regarding exercise impacts on BMI, BMI z-score, blood sugar levels, or insulin resistance due to trial limitations.
• Adherence and Safety Gaps: Existing studies frequently fail to comprehensively report adverse events, emphasizing the necessity for further research.

Analyzing the Clinical Evidence Base

To evaluate the efficacy of movement, investigators searched for studies that compared participating in physical activity to no physical activity or another type of physical activity. The review identified 30 studies encompassing 1,508 participants across 15 countries, including China, Brazil, the United States, and Sweden. Just under half of the study cohort comprised female participants (46%), with average ages ranging from 10 years to nearly 17 years.

When assessing the impact of any physical activity versus physical inactivity across 22 trials, the data demonstrated modest improvements in key anthropometric parameters. Adolescents in the active groups weighed on average 1.88 kg less, had an average waist size 2.88 cm smaller, and an average body fat percentage 2.96% lower than their non-active counterparts. However, evidence regarding systemic metabolic markers—such as blood sugar levels and insulin resistance—remains uncertain.

Summary of Anthropometric Outcomes: Physical Activity vs. No Physical Activity

Outcome Measure	Mean Difference / Effect	Number of Studies (N)	Total Participants (n)
Body Weight	-1.88 kg	17	749
Waist Size	-2.88 cm	10	476
Body Fat Percentage	-2.96%	9	313

Methodological Limitations and Trial Heterogeneity

The analyzed studies were small; sample sizes ranged from a minimum of 21 participants to a maximum of 106. Furthermore, the types of physical activities varied, encompassing everything from aerobic exercise and weight-lifting to football and active video-gaming.

Poor reporting of methods and findings, as well as incomplete outcome data, limit certainty. Crucially, no studies reported on unwanted, harmful events. Comparisons between different exercise types yielded insufficient data to establish the superiority of one regimen over another.

Future Research and Public Health Trajectory

Addressing the burden of adolescent obesity demands larger, longer-lasting, and better-quality studies. Future investigations must prioritize standardized reporting to bridge these knowledge gaps. Until then, the effects of physical activity on other measures of weight, body size, or health problems remain unknown.