The Contribution of Visceral Adiposity and Mid‐Thigh Fat‐Rich Muscle to the Metabolic Profile in Postmenopausal Women

Abstract

This study explored the relationship between muscle fat infiltration derived from mid-thigh computed tomography (CT) scan, central fat distribution and insulin sensitivity in postmenopausal women. Mid-thigh CT scans were used to measure low attenuation muscle surface (LAMS) (0-34 Hounsfield units (HU)), which represented a specific component of fat-rich muscle. Whole-body insulin sensitivity (M/I) was evaluated by an euglycemic-hyperinsulinemic clamp. A group of 103 women aged 57.0 ± 4.4 years was studied. Women with higher levels of LAMS presented higher metabolic risk features, particularly elevated fasting, 2-h plasma glucose (2hPG) concentrations and diminished M/I (P < 0.05). To further study the contribution of muscle fat infiltration and central adiposity on metabolic parameters, we divided the whole group based on the median of LAMS and visceral adipose tissue (VAT). As expected, the best metabolic profile was found in the Low-LAMS/Low-VAT group and the worst in the High-LAMS/High-VAT group. Women with Low-LAMS/High-VAT presented similar metabolic risks to those with High-LAMS/High-VAT. There was no difference between High-LAMS/Low-VAT and Low-LAMS/Low-VAT, which presents the most healthy metabolic and glycemic profiles as reflected by the lowest levels of cardiovascular disease risk variables. This suggests that High-LAMS/Low-VAT is also at low risk of metabolic deteriorations and that High-LAMS, only in the presence of High-VAT seems associated with deteriorated risks. Although increased mid-thigh fat-rich muscle was related to a deteriorated metabolic profile, VAT appears as a more important contributor to alterations in the metabolic profile in postmenopausal women.