OBJECTIVE:The normal body mass index (BMI) range, as defined by the World Health Organization (WHO), is quite wide, and some people within this range may have excessive central fat accumulation and elevated metabolic risks. We hypothesize that the waist-to-height ratio (W/Ht), an effective index for assessing central fat distribution among Japanese people, can be used to identify subjects who are at higher metabolic risk within the normal as well as the overweight range. METHODS: We investigated: (1) the values of BMI, waist circumference, and W/Ht in 6141 men and 2137 women at various age intervals and calculated gender (female to male) ratios for all these anthropometric indices; (2) the relation between age and each anthropometric index, between age and morbidity index for coronary risk factors (sum of the scores for hyperglycemia, hypertension, hypertriglyceridemia, hypercholesterolemia, and low HDL cholesterol; one point for each condition if present), and between morbidity index for coronary risk factors and each anthropometric index; (3) the distributions of the subjects, using various proposed indices of waist circumference (those suggested by WHO, the Japan Society for the Study of Obesity, and the Asia-Pacific perspective), and our proposed boundary value, W/Ht 0.5, among the WHO categories based on BMI; (4) the metabolic risks (coronary risk factors, hyperuricemia, high g-glutamyltransferase, and fatty liver diagnosed by ultrasonography), and exercise habits among normal-weight subjects with W/Hto0.5 or Z0.5. RESULTS: (1) For the various anthropometric indices in all age groups, the gender ratio for W/Ht was closest to 1, indicating that a single set of values for W/Ht can be used for men and women. (2) Height correlated negatively with age. Among the anthropometric indices, only W/Ht correlated positively with age for both men and women, while age and all anthropometric indices, except height, correlated positively with the morbidity index for coronary risk factors. For both men and women, the highest correlation coefficient was between W/Ht and the morbidity index for coronary risk factors. (3) Nearly all overweight men and women (BMIZ25) had W/HtZ0.5 (98.5% of men and 97.5% of women). None of the underweight subjects had W/ HtZ0.5. However, 45.5% of men and 28.3% of women of normal weight (BMI 18.5-o25) had W/HtZ0.5. W/Ht, of all the indices investigated, was the best index for signaling metabolic risk in the normal-weight subjects as well as the overweight subjects. (4) Age-and BMI-adjusted odds ratios for multiple metabolic risks, and history of no habitual exercise were significantly higher in normal-weight men and women with W/HtZ0.5 than in others of normal weight. CONCLUSIONS: Waist circumference is improved by relating it to height to categorized fat distribution of different genders and ages. W/Ht is a simple and practical anthropometric index to identify higher metabolic risks in normal and overweight Japanese men and women.

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OBJECTIVE -To investigate the association between cardiorespiratory fitness and the incidence of type 2 diabetes among Japanese men. RESEARCH DESIGN AND METHODS-This prospective cohort study was conducted in 4,747 nondiabetic Japanese men, aged 20 -40 years at baseline, enrolled in 1985 with follow-up to June 1999. Cardiorespiratory fitness was measured using a cycle ergometer test, and Vo 2max was estimated. During a 14-year follow-up, 280 men developed type 2 diabetes.RESULTS -The age-adjusted relative risks of developing type 2 diabetes across quartiles of cardiorespiratory fitness (lowest to highest) were 1.0 (referent), 0.56 (95% CI 0.42-0.75), 0.35 (0.25-0.50), and 0.25 (0.17-0.37) (for trend, P Ͻ 0.001). After further adjustment for BMI, systolic blood pressure, family history of diabetes, smoking status, and alcohol intake, the association between type 2 diabetes risk and cardiorespiratory fitness was attenuated but remained significant (1.0, 0.78, 0.63, and 0.56, respectively; for trend, P ϭ 0.001).CONCLUSIONS -These results indicate that a low cardiorespiratory fitness level is an important risk factor for incidence of type 2 diabetes among Japanese men. Diabetes Care 26:2918 -2922, 2003A 1997 survey conducted by the Japanese government's Ministry of Health, Labor and Welfare reported the estimated number of patients with type 2 diabetes to be 6.9 million in Japan, and it is currently projected that the number of diabetic patients is dramatically increasing (1). In view of the fact that insulin secretion capacity is reported to be genetically lower among the Japanese than among Caucasians (2,3), Japanese appear to be more prone to the development of type 2 diabetes (4,5). With the overall Japanese lifestyle becoming more like the western lifestyle, a high-fat diet and low physical activity (which are known to be risk factors for the development of type 2 diabetes) are becoming more prevalent in Japan. Therefore, preventing type 2 diabetes is an important issue to be resolved. Because people who have low cardiorespiratory fitness are more likely to be insulin resistant (6), it is reasonable to surmise that a lower cardiorespiratory fitness level is a risk factor for the development of type 2 diabetes.To our knowledge, only two prospective cohort studies have examined the association between cardiorespiratory fitness and the risk of type 2 diabetes.Both studies show an inverse relationship between cardiorespiratory fitness and the development of type 2 diabetes among the western populations (7,8). However, no such studies have been conducted in the Japanese population. Thus, this study was designed to prospectively determine whether low cardiorespiratory fitness in Japanese men is a risk factor for the development of type 2 diabetes. RESEARCH DESIGN AND METHODS SubjectsThe subjects for this study were 5,984 male employees between 20 and 40 years of age who had participated in an annual health examination conducted at the Tokyo Gas Company in 1985. Among these men, 335 were excluded because they were foun...

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BackgroundMetabolic syndrome has received increased global attention over the past few years. Eating behaviors, particularly eating speed, have long been of interest as factors that contribute to the development of obesity and diabetes. The aim of this study was to assess the relationship between eating speed and incidence of metabolic syndrome among middle-aged and elderly Japanese people.MethodsA total of 8941 community residents from Soka City in Saitama Prefecture, aged from 40 to 75 years and without a diagnosis of metabolic syndrome, participated in the baseline survey in 2008 and were followed until 2011. Anthropometric measurements and lifestyle factors were measured at baseline and follow-up. The association between eating speed and incidence of metabolic syndrome was evaluated using Cox proportional hazards models adjusted for potential confounding variables.ResultsDuring the 3-year follow-up, 647 people were diagnosed with metabolic syndrome (25.0 cases/1000 person-years). The incidence rates of metabolic syndrome among non-fast-eating and fast-eating participants were 2.3% and 3.1%, respectively. The multivariate-adjusted hazard ratio for incidence of metabolic syndrome in the fast-eating group compared to the not-fast-eating group was 1.30 (95% confidence interval [CI], 1.05–1.60) after adjustment for the potential confounding factors. Eating speed was significantly correlated with waist circumference and high-density lipoprotein cholesterol (HDL-C) components of metabolic risk factors. Hazard ratios in the fast-eating group compared with the reference group were 1.35 (95% CI, 1.10–1.66) for waist circumference and 1.37 (95% CI, 1.12–1.67) for HDL-C.ConclusionsEating speed was associated with the incidence of metabolic syndrome. Eating slowly is therefore suggested to be an important lifestyle factor for preventing metabolic syndrome among the Japanese.

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Those who engaged in regular physical activity > or =3 days per week appeared to have the fewest coronary risk factors. However, even those engaged in physical activity once per week had fewer CHD risk factors than sedentary individuals.