Insulin sensitivity deteriorates after short-term lifestyle intervention in the insulin sensitive phenotype of obesity.

Objective: To investigate the effects of a 3-month lifestyle intervention on insulin sensitivity and its related cardiometabolic factors in obese patients.

Methods: Anthropometry, body composition, oral glucose tolerance test, lipids, alanine aminotransferase, insulin sensitivity (insulinogenic index (ISI), homeostasis model assessment, β-cell performance (disposition index)) were evaluated in 263 obese women and 93 obese men before and after 3 months of hypocaloric low fat/high protein diet associated with physical activity 30 min/day.

Results: Patients were divided into 3 groups according to the intervention-induced ISI changes: group 1 (decrease), group 2 (stability) and group 3 (increase). Insulin sensitivity and the disposition index were significantly higher before the intervention in group 1 than in group 3. BMI, waist circumference, and fat mass significantly decreased in groups 1 and 3 in both sexes. β-cell performance decreased in group 1 and increased in group 3. Metabolic variables improved in group 3, whereas glucose levels increased in women of group 1. The post-intervention insulin sensitivity was lower in group 1 than in group 3.

Conclusion: Lifestyle intervention induces changes in insulin sensitivity and metabolic factors that depend on the pre-intervention degree of insulin sensitivity. Weight loss leads to metabolic benefits in insulin-resistant, obese patients, whereas it may paradoxically worsen the metabolic conditions in the insulin-sensitive phenotype of obesity.