The Cambridge diet is a commercial very-low-calorie diet (VLCD). The diet was first used only in weight-loss clinics in the United Kingdom. In the early 1980s, the products associated with the diet (powder mix, meal bars, and liquid meals) started selling commercially in the United States and the United Kingdom. Formulations of the Cambridge diet in the United Kingdom differ from that sold in the United States. In both the United Kingdom and North America, the Cambridge products are available only from distributors; they cannot be purchased over the counter at pharmacies or supermarkets.