NAASO Meeting 2005, Vancouver #4
Improvements in Glucose Tolerance and Insulin Resistance Following Weight Loss Persist after Regain of the Lost Weight
P. Ernsberger, R. A. Velliquette, J.L. Johnson and R.J. Koletsky
Fluctuating body weight may impact health. The spontaneously hypertensive obese rat (SHROB) subjected to intermittent very low calorie diet (VLCD), is a model of weight cycling. Previous findings indicated that a transient increase in blood pressure occurs during rapid weight regain, referred to as refeeding hypertension. In the present study, we tested changes in glucose tolerance and insulin resistance. We first studied metabolic events during one cycle of weight lost and regain in SHROB. After a 14d VLCD of Optifast providing one-sixth of baseline calories, SHROB were refed ad lib until their body weight equaled control ad lib fed SHROB. Triglycerides and free fatty acids fell by 55% and 48%, respectively, after VLCD and returned to baseline after refeeding. Oral glucose tolerance and insulin secretion were acutely impaired by VLCD, as shown by reduced insulin area under the curve (AUC) (2800 ± 480 ng*min/mL vs. 6600 ± 2600 ng*min/mL in controls) and elevated glucose AUC (56,700 ± 12,600 mg*min/mL vs. 33,000 ± 5200 mg*min/mL in controls). After refeeding, body weight did not differ (506 ± 21g vs. 517 ± 16g in controls) nor did total combined fat depot mass (172 ± 6 g/kg body weight vs. 170 ± 10 g/kg in controls). Weight cycled SHROB showed reduced glucose AUC (18,000 ± 890 mg*min/mL) with unchanged insulin AUC relative to controls. Subsequent studies tested glucose tolerance 30d after weight regain and the beneficial effect of weight loss was diminished but still significant. Further studies examined three cycles of weight loss and regain. Improved glucose tolerance was also seen. Following initial glucose intolerance immediately after VLCD, weight cycling may create an anabolic state characterized by increased disposal of a glucose load. Thus, improvements in glucose tolerance and insulin resistance from weight loss persist following regain of lost weight.
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