Prevalence of obesity, overweight and underweight in a Hong Kong community: the United Christian Nethersole Community Health Service (UCNCHS) primary health care program 1996-1997.

The aim of this cross-sectional observation study was to assess thoroughly the body mass index (BMI) profile in Hong Kong Chinese and report all categories of BMI cutoff points as suggested by the World Health Organization (WHO). A cohort of 17,242 subjects (4822 men and 12420 women) aged 15 or above from the community of Hong Kong presenting themselves voluntarily from April 1996 to August 1997 for primary health assessment at the Three Health Centers of the United Christian Nethersole Community Health Service (UCNCHS). The mean age (+/- SD) was 51.0 +/- 16.2 years (range 15-96 years, median 49.6 years). The mean BMI of the 17,242 subjects was 23.5 +/- 3.3 kg/m2 in men and 23.0 +/- 3.7 kg/m2 in women. The BMI peaked at age 30 to 50 years in men and 50 to 70 years in women. The age-standardized prevalence of BMI > or = 30 kg/m2 or > or = 25 kg/m2 in Hong Kong Chinese was 3.0% in men and 3.2% in women, and 29.1% in men and 21.3% in women, respectively. For underweight, 35.9% and 27.8% of women and 27.5% and 10.3% of men aged 15-20 and 20-30 years, respectively, had BMI < 18.5 kg/m2. In conclusion, a significant proportion of Hong Kong Chinese had a BMI > or = 25 kg/m2. Among Hong Kong Chinese aged < 30 years, the prevalence of underweight was also high.