This study followed 164 overweight or obese women from Minnesota who were 24 to 44 years old. Half of the women participated in supervised strengthening classes for 16 weeks, and had booster sessions four times yearly with certified fitness professionals. The control group received a brochure recommending 30 minutes to an hour of exercise most days of the week. Neither group was asked to change their diets while participating in the study.
Women who lifted weights decreased body fat percentage by 3.7 percent, while the other group maintained the same body fat. However, the changes in intra-abdominal fat, which is closely associated with heart disease and metabolic disturbances, was more pronounced. The women who did strength training had only a 7 percent in intra-abdominal fat increase vs. the 21 percent increase in the controls group.
This study shows that strength training can prevent increases in body fat percentage and limit increases in the fat most closely associated with heart disease.