Thirty-four million adult Americans are obese (greater than 30% above ideal body weight). 1990 national Health Objectives state that 50% of all adults should adopt weight-loss and exercise regimes. This recommendation has caused a dramatic surge in the number and variety of weight-loss programs currently available. A parallel surge has occurred in the cost of these weight-loss programs. This wide variation in personal expenditure (and treatment provided) necessitates a review of the programs and their cost to the participant. The cost of a 12-week outpatient commercial weight-loss program can range from $2,120 for the most expensive very low-calorie diet program to $108 for the least expensive nutrient-balanced hypocaloric diet program. This article reviews 11 commercial diet programs in the Boston area and analyzes the out-of-pocket cost paid to the clinic by the participant to lose 1 kg on each program. Given the complexity of treatment to achieve long-term weight control, knowledge of financial obligations is important.