Associations between abdominal adiposity, exercise, morbidity, and mortality

Abstract

The increasing prevalence of abdominal obesity worldwide poses a serious public health problem and thus presents a target for research designed to improve the assessment or treatment of abdominal obesity. Specifically, the first study in this thesis investigated the influence of age and gender on visceral (VAT) and abdominal (ASAT) subcutaneous adipose tissue for a given waist circumference (WC) in 481 men and women varying widely in age and body mass index (BMI). Significant gender differences in VAT and ASAT for a given WC were observed; however, only the relationship between WC and VAT was substantially influenced by age. The second study examined whether the associations between VAT, ASAT, and the metabolic syndrome (MetS) were altered depending on the measurement methodology used to assess VAT and ASAT. The odds ratio (OR) for MetS was higher for total VAT volume (OR = 7.26), and for partial volumes at T12–L1 (OR = 7.46) and L1–L2 (OR = 8.77) compared with the classic L4–L5 (OR = 3.94) measurement. The OR for MetS was not substantially different among the ASAT measures (OR∼2.6). Measurement site for VAT, but not ASAT, has a substantial influence on the magnitude of the association with MetS. The third study examined the independent associations between VAT, ASAT, liver fat, and all-cause mortality in 291 men (97 decedents and 194 controls, mortality follow-up of 2.2 ± 1.3 y). In a model including VAT, ASAT, liver fat, age, and length of follow-up, only VAT (1.93 (1.15–3.23)) remained a significant predictor of mortality. We concluded that VAT is a strong, independent predictor of all-cause mortality in men. The purpose of the final study was to determine the effect of aerobic exercise dose (energy expenditure) on WC in sedentary, overweight or obese postmenopausal women (n = 424). The women were randomly assigned to a control group or one of three aerobic exercise groups that exercised at energy expenditures of 4, 8, or 12 kcal·kg body mass–1·week–1. On comparison with controls, there were significant reductions in WC in the exercise groups (~3 cm, p < 0.05), which were independent of weight loss. However, the amount of exercise performed was not associated with reductions in WC in a dose-dependent manner.

The Effect of Lifestyle Interventions on Excess Ectopic Fat Deposition Measured by Noninvasive Techniques in Overweight and Obese Adults: A Systematic Review and Meta-Analysis

“…Only one intervention study was found in which pancreatic adiposity was measured. [63] In this study a training program of six months resulted in a non-significant reduction of pancreas fat. Clearly, more studies are necessary to look at the effect of lifestyle interventions on pancreatic adiposity.…”

“…In 27 articles, the effect of a lifestyle intervention on hepatic fat was discussed. [47,46,50, In the case of muscle [77,61,64,66,68,70,72,76], heart [40,46,54,74,[78][79][80][81] and pancreas [63] adiposity, the number of included papers was eight, eight and one respectively. There effects on multiple ectopic fat locations (e.g.…”

Dead adipocytes, detected as crown-like structures, are prevalent in visceral fat depots of genetically obese mice

“…The phenomenon is a major public health concern, mainly because it carries an increased risk of death from obesity-associated disorders (3,4). Obesity is frequently associated with metabolic syndrome; insulin resistance is widely suspected as the central starting event of the condition (1).…”