There is now a pandemic of chronic diseases in Asian countries, driven mainly by obesity, diabetes and cardio-renal complications. In Hong Kong, the reported prevalence of obesity, defined as body mass index (BMI) ≥ 25 kg m−2, varied from one-quarter to one-third of the population. In a population-based survey conducted in 1995, 16.7% of Hong Kong adults had the metabolic syndrome (MES) (National Cholesterol Education Programme criterion). Obesity is now a global concern not only in adults but also among children and adolescents. In 2003, a territory-wide survey in Hong Kong reported the prevalence of central obesity and MES to be 9.0% and 2.4%, respectively, in Chinese adolescents. Overweight, positive family history of diabetes and studying at schools of lower academic grading were independent risk factors for the adolescent MES. Lifestyle modification with proper diet and exercise is essential for health protection. In accord with western data, a weight management programme in Hong Kong Chinese with a 4–6% reduction in body weight or waist circumference was associated with significant reductions in all cardiovascular risk factors. Psychosocial factors related to chronic diseases are also of growing concern. In Hong Kong Chinese, increasing BMI was associated with a lower number of sleeping hours and increasing working hours, suggesting an intimate relationship between physical health and psychosocial stress. Chronic non-communicable diseases are therefore major health threats in Hong Kong, with obesity as one of the major risk factors. A multidimensional and multidisciplinary health promotion and disease management plan is urgently needed to control these epidemics.