Dysmetabolic signals in "metabolically healthy" obesity.

Background: Obesity is associated with decreased insulin sensitivity, atherogenic dyslipidemia and hypertension, but clinical studies have also identified a "metabolically healthy" obese phenotype.

Objective: To compare the characteristics of so-called "metabolically healthy" obese (MHO), normal weight subjects (MHNW) and obese with insulin resistance in the United States National Health and Nutrition Examination Survey, 1999-2004 (NHANES).

Design, Setting And Participants: Insulin resistance was defined by a homeostatic model assessment (HOMA) value in the upper tertile for the entire NHANES cohort. "Metabolic health" was defined as the absence of diabetes, insulin resistance, metabolic syndrome, and lipid-lowering therapy. The study evaluated the 314 MHO, 1173 MHNW and 843 insulin-resistant obese from among the 6485 non-diabetic, non-pregnant adults aged 20-79 years.

Main Outcome Measures: Demographic, metabolic, nutrition and physical activity features.

Results: MHO and MHNW groups were similar regarding age, and fasting glucose and triglyceride levels. MHO had higher insulin (P < 0.0001), insulin resistance as measured with the homeostatic model (P < 0.0001), non-HDL cholesterol (P = 0.002 in females and P = 0.049 in males) and C-reactive protein levels (P < 0.0001 in females and P = 0.038 in males), and lower high-density lipoprotein cholesterol (HDL) levels (P < 0.002). In addition, MHO females had higher low-density lipoprotein (LDL) cholesterol levels (P = 0.012) and systolic blood pressure (P = 0.02), and lower intake of dietary fiber (P = 0.0009) and levels of physical activity (P = 0.002). Triglycerides levels were normal in the MHO group.

Conclusions: "Metabolically healthy" obese people have multiple dysmetabolic changes that may signal increased risk for coronary artery disease.