Metabolic Effects of Obesity

The primary metabolic effects of obesity include dyslipidemias, glucose intolerance, and insulin resistance expressed primarily in the liver, skeletal muscle, and adipose tissue. These metabolic abnormalities reflect molecular signals originating from the increased mass of adipocytes . [Note: About 30% of obese individuals do not show these metabolic abnormalities.]
A. Metabolic syndrome
Abdominal obesity is associated with a cluster of metabolic abnormalities (hyperglycemia, insulin resistance, hyperinsulinemia, dyslipidemia [low levels of high-density lipoprotein (HDL) and elevated TAG], and hypertension) that is referred to as the metabolic syndrome (Fig. 1). It is a risk factor for CVD and T2D. The low-grade, chronic, systemic inflammation seen with obesity contributes to the pathogenesis of insulin resistance and T2D and likely plays a role in metabolic syndrome. In obesity, adipocytes release proinflammatory mediators such as IL-6 and TNF-α. Additionally, levels of adiponectin, which normally dampens inflammation and sensitizes tissues to insulin, are low.

Figure 1:  Body mass index and changes in blood lipids. HDL = high-density lipoprotein.
B. Nonalcoholic liver disease
Obesity is associated with ectopic deposition of TAG in the liver (hepatic steatosis) and results in increased risk for nonalcoholic fatty liver disease ([NAFLD]).