The first 50 websites identified on searching the Internet for 'weight loss
diets' were assessed systematically and their content compared with publis
hed clinical guidelines for management of obesity. The relevance and qualit
y of the sites varied enormously. Only 3 confined themselves to sound dieta
ry advice. Most promoted dietary supplements or other 'slimming aids', ofte
n of uncertain composition and based on dubious physiological principles. P
otential hazards-for example, those of very low calorie diets-were rarely h
ighlighted and certain regimens on offer were potentially dangerous.