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Angela M. Dingels '01

Impact of Exercise and Diet on Weight Loss and Body Composition in Obese Adolescents.


Purpose: Obesity is a common health problem in children and adolescents. The prevalence of adolescent obesity has doubled in the last three decades. A great percentage of obese children become obese adults, which is associated with increased morbidity and mortality. Despite the increasing numbers of obese children, intervention programs have met with limited success. Rapid weight loss in obese children has been associated with a decrease in metabolic rate due to loss of fat-free mass, and consequent difficulty maintaining weight loss. The impact of a residential summer weight loss camp on weight loss and body composition was studied.

Methods: Forty-nine female adolescents age 12 to 16 years (mean=13.6) were evaluated over a period of 6 weeks. Subjects followed the camp regimen for diet and exercise. The camp diet provided approximately 1448 total calories per day, comprised of 68% CHO, 20% protein, and 12% fat. Subjects exercised with varying intensity for roughly four hours per day. Assessment included height, weight, body mass index, percent body fat, lean body mass, and waist-to-hip ratio. Percent body fat was estimated using skinfold measurements (triceps and calf), near-infrared interactance, and circumference measurements. Mid-arm muscle circumference was used to determine change in lean body mass.

Results: Subjects lost an average of 16.6 pounds during the six-week trial (p<0.001). The mean BMI decreased from 30.9 to 27.7 (p<0.001). Body fat percentage, as estimated by skinfold measurements, decreased from 55.2% baseline to 53.5% (p<0.05). The near infrared interactance method estimated a percent body fat decrease from 35.2% to 32.3% (p<0.001). Circumference measurements predicted a percent body fat decrease from 38.8% baseline to 33.1% (p<0.001). Mid-arm muscle circumference, a measurement of fat-free mass, did not change significantly (p>0.05). Baseline waist-to-hip ratio was 0.83, and treatment was 0.82. Waist-to-hip ratio did not change significantly (p>0.05).

Conclusion: Following the camp regimen, subjects lost weight and body fat, while preserving their LBM. Since changes in LBM can predict the long-term success of weight loss in obese children, weight reduction programs for obese children should include emphasis on both weight reduction and maintenance of fat-free mass.

Faculty Mentor: Patricia Marincic, PhD, RD