Background: As obesity prevalence and health-care costs increase, Health Care providers must prevent and manage obesity cost-effectively. Methods: Using the 2006 NICE obesity health economic model, a primary care weight management programme ( Counterweight) was analysed, evaluating costs and outcomes associated with weight gain for three obesity-related conditions ( type 2 diabetes, coronary heart disease, colon cancer). Sensitivity analyses examined different scenarios of weight loss and background ( untreated) weight gain. Results: Mean weight changes in Counterweight attenders was -3 kg and -2.3 kg at 12 and 24 months, both 4 kg below the expected 1 kg/year background weight gain. Counterweight delivery cost was 59.83 pound per patient e...