, men with a waist size of 85 cm or more and women whose waists are 90 cm or more are considered obese. The health ministry uses these criteria in metabolic syndrome checkups.
The latest move comes amid questions over why the threshold for men in Japan is stricter than that overseas, and lower for men than women.
The criteria adopted by the research group in 2000 were based on data collected mainly from overweight people.
Measuring the waist gives a rough measure of excessive abdominal fat, which is a risk factor for lifestyle-related diseases, including diabetes.
Experts at the research group are now considering new limits for appropriate waist sizes using data on more than 10,000 people, and analyzing the association between abdominal fat, waist size and lifestyle-related diseases, according to gender and various age brackets.
The team will also look into how the waistline is related to risk of illness and death rates.
A 2008 survey by the Ministry of Health, Labor and Welfare found about half of Japanese men aged 40 to 74 and around 20 percent of women in the same age bracket are either "suspected of having metabolic syndrome" or "considered to be metabolic syndrome patients."