Health risks among Japanese men with moderate body mass index

Despite the westernized lifestyle, most Japanese are not prominently obese. As their obesity may be obscured, we want to further explore central fat distribution and health risks among this population.

2668 men (body mass index (BMI) 20- < 26.4 kg/m2) were identified from 3343 men (BMI 14.0-37.7, median of waist-to-height ratio (W/Ht) 0.50) who underwent routine health examinations. They were divided into four groups: (1) BMI 20- < 24, W/Ht < 0.50; (2) BMI 20- < 24, W/Ht > or = 0.50; (3) BMI 24- < 26.4, W/Ht < 0.50; and (4) BMI 24- < 26.4, W/Ht > or = 0.50. The metabolic risks and physical activities were compared.

W/Ht > or = 0.50 comprised 35% of the subjects of BMI 20- < 24, 91% of BMI 24- < 26.4, only 1% of BMI < 20 and up to 99% of BMI > or = 26.4. After adjusting for age and smoking and with group 1 as the reference group, odds ratios (ORs) were significantly higher in both groups 2 and 4 for the risk of hypertension (1.42, 1.98), hyperglycaemia (1.49, 1.78), hypertriglyceridaemia (1.95, 2.56), low HDL cholesterol (1.87, 2.20), hyperuricaemia (2.00, 2.51) and fatty liver (2.57, 5.64) and additionally in group 4 for hypercholesterolaemia (1.35). ORs in group 3 were only significantly higher for risk of hypertension (1.86) and fatty liver (1.89). Significantly lower frequencies of regular physical activity were noted in the higher W/Ht groups (0.75, 0.47, 1.10, 0.52 days per week, from groups 1-4, respectively).

Measurement of waist circumference may be a preliminary method for the survey of people at higher risk of lifestyle-related disorders in Japanese men, especially among those with moderate BMI.