Objective: Intensive weight loss programs that incorporate dietary counselling and exercise advice are popular and are supported by evidence of immediate weight loss benefits. We evaluate the cost-effectiveness of two weight loss programs, Lighten Up to a Healthy Lifestyle and Weight Watchers. Methods: Health gains from prevention of chronic disease are modelled over the lifetime of the Australian population. These results are combined with estimates of intervention costs and cost offsets (due to reduced rates of lifestyle-related diseases) to determine the dollars per disability-adjusted life year (DALY) averted by each intervention program, from an Australian health sector perspective. Results: Both weight loss programs produced small improvements in population health compared to current practice. The time and travel associated with attending group-counselling sessions, however, was costly for patients, and overall the cost-effectiveness ratios for Lighten Up ($130,000/DALY) and Weight Watchers ($140,000/DALY) were high. Conclusion: Based on current evidence, these intensive behavioural counselling interventions are not very cost-effective strategies for reducing obesity, and the potential benefits for population health are small. Implications: It will be critical to consider other strategies (e.g. changing the 'obesogenic' environment) or explore alternative methods of intervention delivery (e.g. Internet) to see if they offer a more cost-effective approach by effectively reaching a high number of people at a low cost. © Public Health Association of Australia.