Very low calorie diets--history, safety and recent developments.

Poor results from orthodox diets for the obese have emphasized the need for suitable alternatives such as very low calorie diets (VLCD). These have now been in use for some ten years and their advantages and pitfalls are well known. Initial investigations were based on the use of total fasting and examining the significance of protein supplementation during therapeutic starvation. Subsequent studies employed ordinary food stuffs as the protein source but included no carbohydrate. Others developed formula diets which involved the use of both protein and carbohydrate. In the U.S.A. diets such as these are either monitored by the medical profession or in some instances sold directly to the public. In these connections two areas of concern have emerged. One is the ability of patients to maintain weight loss and most importantly, the safety of the programme itself. It is now well established that unless some follow-up support is made available patients will not be stabilized at the reduced weight level. The use of behaviour modification, increased physical activity and the concept of free and fixed calories offers the hope of a more complete answer to weight control. The safety of VLCD became a cause for concern when liquid protein sold over the counter was associated with a number of deaths for which other causes could not be determined. Subsequent monitoring has indicated that where patients are maintained on high quality protein supplement the potentially lethal arrhythmias associated with liquid protein are not seen. On the basis of clinical experience in over 4000 patients it is felt that three factors are necessary for any programme to be maximally safe and efficient. These elements are proper patient selection, high quality supplement and proper patient monitoring.