Many of the factors that lead to a successful weight loss diet remain unclear. In controlled trials, patients in the placebo group often achieve impressive results. These results may be due to the ambiance of the trial or weight loss program, particularly regular contact with staff, and the belief that the treatment is novel and likely to be successful. Summerbell and colleagues studied the role of novelty and simplicity in weight loss programs.

Forty-five adults referred to an obesity clinic were included in the study. Patients had a body mass index of more than 27, were willing to follow diet management and had no contraindications to calorie restriction. Patients were excluded from participation if they had diabetes or were pregnant or lactating. The patients were randomly assigned to follow one of three diets for 16 weeks. Each of the diets was designed to produce an energy deficit of four to seven mega-joules per day. The patients in the control group were instructed in a conventional balanced diet of normal foods. Patients following the novel “milk-only” program were restricted to a simple diet of milk and unsweetened yogurt. The third group of patients followed a “milk-plus” diet in which they could select a favorite food to supplement a basic milk diet.

Nine of the 14 control subjects completed the 16-week program. Eleven of 14 study subjects completed the milk-only diet and 11 of 17 subjects completed the milk-plus diet. The mean weight loss was 2.6 kg (5.7 lb) in the control subjects, 11.2 kg (24.6 lb) in the milk-only group and 8.2 kg (18.0 lb) in the milk-plus group. The results for the milk-only diet were superior to reported losses in trials of appetite suppressant and other dietary medications.

The authors emphasize that the trial took place under realistic conditions. Patients had no incentive except their own wish to lose weight. They bought supplies at their usual grocery stores, used no medical or surgical adjuvant treatment and were not provided with additional exercise or behavior therapy. No side effects were reported except constipation, and no evidence of nutritional deficiency was noted. The authors attribute the success of the restricted diets to novelty and simplicity. Compliance was higher for the two novel diets than for the conventional diet.

The authors conclude that novelty and simplicity are key to the success of a short-term diet for weight reduction. They do not recommend these diets for prolonged periods but emphasize that these novel diets have results that rival those of drug treatments. The authors suggest that various diets could be rotated to sustain patient confidence during prolonged weight loss.