Issue 171 Item 12 Seven to Ten Percent Weight Loss Through Exercise Provides Con

Patients who exercised just for ½ hour for 5 days a week, lost 7% of their body weight and showed a 57% improvement in their insulin sensitivity.

Lais Monzillo, MD, Federal University Hospital of Sao Paolo, Brazil, said insulin-resistant patients who lost an average of 7.1% of their weight while on a six-month diet and exercise program had a 56.8% percent improvement in insulin sensitivity index.

"You don’t need a lot of weight loss — maybe 7% to 10% — for you to see a lot of difference," Dr. Monzillo said at her poster presentation.

Dr. Monzillo performed her study at the Joslin Diabetic Center, Boston, Massachusetts, U.S.A., where she enrolled 24 insulin-resistant obese subjects with varying degrees of glucose tolerance (8 with normal glucose tolerance, 8 with impaired glucose tolerance and 8 with type 2 diabetes). The subjects completed a 6-month program of weight reduction through diet restriction and moderate-intensity physical exercise.

"We had the patients exercise five times a week for 30 minutes a day at 75% of maximum heart rate," Dr. Monzillo noted.

Serum levels of adipokines — leptin, adiponectin, resistin, tumour necrosis factor and high sensitivity C-reactive protein — were measured before and after intervention.

Patients lost 7.1% of weight; 7.4% of body mass index and 3.3% in their waist-to-hip ratio. Those results, as well as the 56.8% gain in insulin sensitivity index, were all statistically significant (P<0.001). The other adipokines were not affected significantly.

The average weight of the subjects dropped from 106.1 kg to 98.7 kg; average body mass index fell from 36.7 kg/m2 to 34.0 kg/m2.

Dr. Monzillo also found decreases in leptin levels, tumour necrosis factor and fasting plasma glucose.

"We saw similar changes in our study," said Petra Beye, MD, City Hospital, Magdeburg, Germany. Dr. Beye examined endothelial dysfunction as measured by ultrasound examination of the brachial artery in the arms. At baseline, obese subjects in her study showed a marked decrease in flow-mediated dilation in the blood vessel. The function returned to the levels seen in normal individuals after six weeks of exercise training.

Dr. Beye said the study indicated that "if you start early with exercise… insulin resistance and diabetes are reversible." Her patients were not instructed in losing weight, and after the eight-week trial, no weight loss was seen. Tests showed, however, that most of the patients had been able to reduce fat mass and replace it with smooth muscle, suggesting that fitness might be more important than weight loss among diabetics.

Getting patients to complete a diet and exercise program, though, can be difficult. Dr. Monzillo noted that she had recruited 35 patients into the study, but only 24 were able to complete the program.

IDF: [Study title: Effect of combined weight reduction and increased physical activity on adipokines in obese subjects with the insulin resistance syndrome. Abstract 1908] and [Study title: Exercise training normalises obesity associated vascular dysfunction in adolescents without changes in total body mass. Abstract 1904]