Home exercise program on change in body weight and metabolic factors in non-obese women

The study investigated the effectiveness of home-based exercise combined with a slight caloric restriction on weight change during 12 months in non-obese women. In addition, the effects of baseline insulin resistance (IR) on modulation of weight change were evaluated. Data was from a randomized clinical trial with a factorial design that was conducted from 2003 to 2005. Two hundred three middle-aged women, 25-45 years, were randomly assigned to exercise [control (CG) or home-based exercise (HB)] and diet intervention [low glycemic index (LGI) or high glycemic index (HGI)]. The HB group received a booklet on aerobic exercise that could be practiced at home (3 times/week - 40 min/session), in low-moderate intensity, during 12 months. Monthly dietary counseling was based on a small energy restriction (100-300 kcal per day), with 26-28% of energy as fat. For each diet meal there was an average difference of 40 units of GI compared to the HGI diet based on published GI values, using white bread as the standard GI of 100%. The HB experienced a greater weight loss in the first 6 months (-1.4 vs. -0.8 kg; p=0.04), but after 12 months there was no differences between groups (-1.1 vs. -1.0; p=0.20). Of the serum biochemical markers, HDL-cholesterol showed major change, with an increase at month 12 of 18.3 mg/dl in the HB compared to 9.5 in the CG (p<0.01). At baseline the non-IR group (n=121) compared to IR (n=64) had similar values of BMI (26.7 vs. 26.3 p=0.21), but statistically significant lower values of waist, glucose, insulin and HOMA-IR, as expected. Women classified as IR at baseline had greater weight loss after 12 months of follow-up (-1.6 kg vs. -1.1 kg; p=0.01) independently of the intervention. The HB exercise helped to reduce weight only among NIR women (-1.5 vs. -0.7; p=0.04) and no differences were observed between intervention groups for IR women (-1.5 vs. -1.7; p=0.24). During follow-up, changes were more pronounced among those women in the HGI diet. These differences were statistically significant for weight and BMI and were greater among the IR (-2.1 kg vs. -1.0 kg; p=0.005 and 0.8 vs. -0.4 kg/m2; p=0.007) compared to the non-IR (-1.4 kg vs. -0.8 kg; p=0.04 and -0.5 vs. -0.3 kg/m2; p=0.05). Changes in HOMA-IR after 3 months of follow-up were different comparing non-IR with IR at baseline. The IR had a reduction in the HOMAIR, whereas in the non-IR this value increased (-0.73 vs. +0.37; p=<0.001). Also this reduction was greater among high compared to LGI diet (p=0.04). To conclude, home-based exercise promoted greater weight reduction during the first six months after which no further benefits are observed. Continuous favorable changes in HDL-cholesterol after 1 year suggest that home-based exercise promote health benefits. In addition, insulin resistance facilitated weight loss, and home-based exercise promoted greater weight loss only in non-insulin resistance women.