The strong and consistent relationship observed between body weight and blood pressure develops early in life, and overweight/obesity in adult life is a good predictor of hypertension. Weight reduction leads to a decrease in blood pressure and prevention of weight increase lowers the incidence of hypertension, but obesity is not necessarily the direct cause of raised blood pressure. Obesity is not established as an independent risk factor for stroke beyond its association with other risk factors. Obesity is a relatively weak risk factor for coronary heart disease (CHD) but it is closely associated with almost all other coronary risk factors. Thus, becoming obese on a Western high fat diet, with development of excess central fat, promotes atherogenesis through a wide range of biochemical and hormonal parameters, including insulin sensitivity. The obesity-CHD relationship is further confused by the weight loss associated with smoking and smoking-related disease, and is confounded by risk factors that accompany the development and maintenance of obesity. Weight loss in middle-aged populations does not apparently lower CHD incidence, possibly because of lack of specificity in methods of weight reduction. Irrespective of the mechanisms involved, early prevention of atherogenic weight gain in young adulthood is an important public health goal towards the control of hypertension and CHD.