PROTEIN-INTAKE DURING AGGRESSIVE CALORIE RESTRICTION IN OBESITY DETERMINES GROWTH-HORMONE RESPONSE TO GROWTH HORMONE-RELEASING HORMONE AFTER WEIGHT-LOSS

OBJECTIVE We evaluated the influence of two types of calorie restricti on, total fast or very low calorie diet, on GH responsiveness to GHRH in severely obese patients. DESIGN Twenty patients with massive obesit y underwent one of two types of calorie restriction, total fast (10 pa tients) or very low calorie diet (10 patients). MEASUREMENTS Fasting G H, IGF-I, glucose, insulin and GH secretion after GHRH (100 ug i.v.) w ere assessed in all patients before and after diet therapy. RESULTS Bo th types of diet produced similar weight reduction (total fast, 5.6 +/ - 1.6 kg/m2 vs very low calorie diet, 5.6 +/- 1.5 kg/M2 mean +/- SD). A significant increase in the integrated GH secretion was observed aft er weight-loss with very low calorie diet (17 +/- 9 vs 27 +/- 12 mU/l min; P < 0.05). However, no change was found in GH response after weig ht loss with total fast (13 +/- 5 vs 15 +/- 7 mU/l min). Glucose, insu lin and IGF-I levels showed a significant decrease with weight reducti on which was similar for both groups. CONCLUSION These findings sugges t that the type of dietary manipulation during calorie restriction in obese patients may influence the changes in GH response to GHRH after weight loss.