| Abstract: | A recent study found that increases in insulin sensitivity following weight loss and stabilization were strongly related to subsequent weight regain. The present paper analyzed this relationship in two behavioral weight-loss programs. In the first study, 125 nondiabetic subjects were followed over 30 months; weight losses averaged 10 kg at six months, and subjects had regained 8 kg of their weight loss by their 30-month follow-up. Neither fasting insulin levels at six months nor changes in fasting insulin from zero to six months were related to subsequent weight regain. Similarly, insulin levels measured two hours after a 75 g glucose load were unrelated to subsequent weight regain. The second study followed 33 individuals with Type II diabetes, treated with behavior modification, and either a low calorie diet or a very low calorie diet. Weight losses averaged 18 kg at six months, and subjects had regained 10 kg by their 24-month follow-up. The Bergman minimal model was used to assess insulin sensitivity at 6-month intervals. Initial analyses suggested that changes in insulin sensitivity from zero to six months were related to subsequent weight regain, but this effect was strongly influenced by an outlier. After removing this individual, there were no significant relationships between the changes in insulin sensitivity that accompanied weight loss and future weight regain. Likewise, insulin sensitivity at 12 months did not predict weight regain from 12 to 24 months. These data do not support the hypothesis that increases in insulin sensitivity with weight loss are associated with subsequent weight regain. |
