Prevalence and Characteristics of Metabolically Obese but Normal Weight and Metabolically Healthy but Obese in Middle-aged Koreans: the Chungju Metabolic Disease Cohort (CMC) Study

ABSTRACT

BACKGROUND: We attempted to determine the prevalence and characteristics of metabolically obese but normal weight (MONW) and metabolically healthy but obese (MHO) individuals in a large cohort of middle-aged Koreans. METHODS: 8,987 non-diabetic subjects were selected from the Chungju Metabolic disease Cohort Study performed in 2003-2006. MONW was defined as a body mass index (BMI) > or = 18.5 and or = 25 kg/m2 with HOMA-IR in the lowest quartile. RESULTS: The mean age of the subjects was 62.3 +/- 10.5 years (men 40.4%). The age-adjusted prevalence of MONW and MHO were 4.3% (5.3% men, 3.7% women) and 5.6% (3.6% men, 7.0% women), respectively. 14.2% of men and 12.9% of women were classified as MONW among the normal weight population, whereas 10.7% of men and 14.5% of women were classified as MHO among the obese subjects. The prevalence of prediabetes was significantly higher in the MONW group than in the MHO group (34.7 vs. 12.5%, P < 0.0001 in men; 23.1 vs. 8.8%, P < 0.0001 in women). The MONW group evidenced an equivalent risk of coronary heart disease (CHD) relative to the MHO group (10.77 +/- 0.68 vs. 10.22 +/- 0.90% in men; 7.02 +/- 0.34 vs. 7.26 +/- 0.26% in women, means +/- standard error [SE]). CONCLUSION: The subjects in the MONW group are characterized by a high risk of diabetes and CHD, despite their normal weights. Their substantial prevalence in the population emphasizes the importance of identifying subjects in the MONW group, and warrants more intensive risk management.