Neck circumference is a better correlate of insulin resistance markers than other standard anthropometric indices in patients presenting severe obesity.

BACKGROUND: Previous studies have demonstrated stronger associations between metabolic alterations and neck circumference (NC) than with body mass index (BMI) or waist circumference (WC). However, most of these studies were performed in individuals presenting overweight or mild obesity. OBJECTIVE: To determine which adiposity index among BMI, WC, NC and fat mass (FM) can best predict metabolic alterations in men and women presenting severe obesity. METHODS: Anthropometric and plasma biochemical parameters were measured in 81 participants presenting severe obesity (19 men, 62 women; age: 44.5 ± 8.9 years; BMI: 43.5 ± 4.1 kg/m2). Multiple linear regressions were used to determine the best predictors of metabolic alterations among each adiposity index. RESULTS: NC was positively correlated with fasting insulin concentrations, C-peptide concentrations and HOMA-IR values and negatively correlated with HDL-C concentrations. NC was the best predictor of glucose homeostasis indices and HDL-C concentrations in models also including sex, BMI, WC, and FM. The ROC curve analysis indicated that a NC ≥ 37.8 cm best predicted type 2 diabetes. CONCLUSIONS: NC seems a better predictor of insulin resistance and lower HDL-C concentrations in patients presenting severe obesity compared to other standard anthropometric indices, and particularly in women. The small sample size in men prevent us to draw clear conclusions. NC could be useful in targeting patients with metabolic alterations who could benefit from medical or surgical treatment of obesity.

Association between Visceral Adiposity Index, Binge Eating Behavior, and Grey Matter Density in Caudal Anterior Cingulate Cortex in Severe Obesity.

Visceral adipose tissue accumulation is an important determinant of metabolic risk and can be estimated by the visceral adiposity index (VAI). Visceral adiposity may impact brain regions involved in eating behavior. We aimed to examine the association between adiposity measurements, binge eating behavior, and grey matter density. In 20 men and 59 women with severe obesity, Grey matter density was measured by voxel-based morphometry for six regions of interest associated with reward, emotion, or self-regulation: insula, orbitofrontal cortex, caudal and rostral anterior cingulate cortex (ACC), ventromedial prefrontal cortex (vmPFC), and dorsolateral prefrontal cortex (DLPFC). Binge eating behavior, depression and impulsivity was assessed by the Binge Eating Scale, Beck Depression Inventory and UPPS Impulsive Behavior Scale, respectively. Men and women were distinctively divided into two subgroups (low-VAI and high-VAI) based on the mean VAI score. Women with high-VAI were characterized by metabolic alterations, higher binge eating score and lower grey matter density in the caudal ACC compared to women with low-VAI. Men with high-VAI were characterized by a higher score for the sensation-seeking subscale of the UPPS-Impulsive Behavior Scale compared to men with low-VAI. Using a moderation-mediation analysis, we found that grey matter density in the caudal ACC mediates the association between VAI and binge eating score. In conclusion, visceral adiposity is associated with higher binge eating severity in women. Decreased grey matter density in the caudal ACC, a region involved in cognition and emotion regulation, may influence this relationship.

Deciphering the Association Between Hypothalamus-Pituitary-Adrenal Axis Activity and Obesity: A Meta-Analysis.

OBJECTIVE: Both the cortisol awakening response (CAR; corresponding to the state measurement) and hair cortisol concentration (HCC; corresponding to the trait measurement) are considered reliable markers of hypothalamus-pituitary-adrenal axis activity. Because cortisol has long been associated with adiposity, this systematic review and meta-analysis aims to summarize and compare the literature around CAR and HCC and their association with obesity or fat distribution indices. METHODS: The PubMed, Web of Science (Web of Science Core Collection and Medline), EBSCO Information Services, Embase, and PsycNET databases were searched, and full-text articles investigating the association between CAR or HCC and markers of adiposity in humans were included. Meta-analyses were then performed to compare studies associating CAR or HCC with BMI (a marker of general adiposity) and waist circumference (a marker of fat distribution). RESULTS: The results of this review highlight inconsistencies in cortisol sampling and CAR computation, which makes comparisons between studies difficult. It was found that adiposity indices are not associated with CAR but that they correlate significantly and positively with HCC. The subgroup analysis hinted to possible age differences in the magnitude of the association between HCC and BMI. CONCLUSIONS: Trait rather than state measurement of the hypothalamus-pituitary-adrenal axis activity is associated with increased general and abdominal adiposity in humans.