Whole-body and adipose tissue glucose metabolism in response to short-term fasting in lean and obese women

Background: Alterations in glucose metabolism during early fasting may be an important trigger of the hormonal and metabolic responses to fasting. Objective: The purpose of this study was to determine whether glucose metabolism in response to brief starvation differs in lean and abdominally obese women. Design: We evaluated whole-body glucose metabolism by use of stable-isotope tracer methods and glucose uptake in subcutaneous abdominal adipose tissue by use of arteriovenous balance in 7 lean [58 ± 2 kg; body mass index (BMI; in kg/m²): 21 ± 5] and 6 abdominally obese (96 ± 2 kg: BMI: 36 ± 1) women after 14 and 22 h of fasting. Results: Between 14 and 22 h of fasting, whole-body glucose production and disposal declined in both groups (P < 0.05), but the reduction was 50% greater in lean than in obese women (P < 0.05). The decline in glucose uptake at 22 h of fasting was also lower in obese (0.11 ± 0.04 μmol·100 g^-1·min^-1) than in lean (0.26 ± 0.03 μmol·100 g^-1·min^-1) women (P < 0.05). Decreases in plasma insulin and leptin concentrations between 14 and 22 h of fasting were also lower in obese than in lean women (insulin: 20 ± 3% and 32 ± 5%: leptin: 18 ± 3% and 37 ± 6%; both P < 0.05). Conclusions: The normal decline in glucose production and uptake that occurs during early fasting is blunted in women with abdominal obesity. These alterations in glucose metabolism are associated with a blunted decline in circulating concentrations of both insulin and leptin, which may explain some of the differences in the metabolic response to fasting observed between lean and abdominally obese persons.