Strength Training Helps Prevent Fat Gain in Overweight, Obese Premenopausal Women

September 24, 2007 — Strength training effectively prevents increases of percentage body fat and attenuates increases of intra-abdominal fat in overweight and obese premenopausal women, according to the results of a 2-group, randomized controlled trial reported in the September issue of the American Journal of Clinical Nutrition.
"American women aged 25 - 44 y gain 0.5 - 1 kg yearly, most of which is fat," write Kathryn H. Schmitz, from the University of Pennsylvania School of Medicine in Philadelphia, and colleagues from the Strong, Healthy, and Empowered study. "Because few midlife women participate in strength training, this mode of activity may be a novel intervention for preventing age-associated fat increases in this population."
An ethnically diverse sample of 164 overweight and obese women was randomized to twice-weekly strength training for 2 years (treatment group) or to a standard care (comparison) group that received brochures recommending aerobic exercise. Age range was 25 to 44 years; body mass index (BMI) was 25 to 35 kg/m2. Computed tomography scan to measure intra-abdominal fat and dual-energy x-ray absorptiometry to measure body fat and fat-free mass were performed at baseline, 1 year, and 2 years.
Changes in percentage body fat during the 2-year study were –3.68% ± 0.99% for the treatment group vs –0.14% ± 1.04% for the control group (P = .01). Changes in intra-abdominal fat were 7.05% ± 5.07% for the treatment group vs 21.36% ± 5.34% for the control group (P = .05).
"This study suggests that strength training is an efficacious intervention for preventing percentage body fat increases and attenuating intraabdominal fat increases in overweight and obese premenopausal women," the study authors write. "This is relevant to public health efforts for obesity prevention because most weight gain can be assumed to be fat, including abdominal fat."
Limitations of the study include greater loss to follow-up in the standard care group and lack of objective monitoring of dietary changes.
"Because these women are already overweight or obese, weight-loss efforts would be desirable," the study authors conclude. "That said, obesity prevention interventions such as twice-weekly strength training are vital to our efforts to slow the increase in population prevalence of obesity and weight gain among overweight and obese women. These findings are particularly relevant to an aging population and the avoidance of the development of sarcopenic obesity in the elderly."
The National Institute of Digestive and Kidney Disease and the University of Minnesota's General Clinical Research Center supported this study. Fitball USA supplied balls for participant incentives. Dr. Schmitz has disclosed receiving a fellowship for this research at the American Heart Association's Council on Epidemiology and Prevention annual meeting.
Am J Clin Nutr. 2007;86:566-572.