Twenty Years of Transitional Changes of Waist Circumference First Introduced as a Basic Item in the Ningen Dock in Japan

Abstract

 In 1999, waist circumference (WC) as a basic item in the Ningen Dock was first introduced at the Jikei University in Japan. A WC of 85 cm in men and 90 cm in women equaling to visceral fat areas 100 cm². WC, which indicates the accumulation state of visceral fat, is easily measured. These data cutoff points were applied as criteria of the metabolic syndrome associated with cardiovascular disorders. Obesity is defined in Japan as a body mass index (BMI) ≥25 kg/m². The total number of subjects that underwent the Ningen Dock from 1999 to 2018 was 122,567 men and 54,267 women, aged 30-79 years old. The criterial data of WC and BMI were calculated by sex and age group every year. In order to clarify transitional changes, data were analyzed with linear approximation. In the 20-year period, both BMI and WC increased in the 55-69 years old groups of both sexes and decreased in the 30-39 years old group in men. In the 40-54 years old groups of both sexes and the 70-79 years old group in men, BMI increased, but WC decreased. In women, both BMI and WC decreased in the 30-34 years old group and the 65-69 years old group, and increased in the 50-64 years old group. The remaining age groups showed a decrease in BMI and an increase in WC. The two national publications on abdominal circumference are the Specific Health Report Survey and the National Health and Nutrition Survey. The data in this study were similar to the results of the former survey conducted in the large population.