Obesity resists the usual fix: no drug on the market reverses it, and most name-brand diets that promise fast results skip over what it actually takes to keep weight off long term. This film, the second installment in HBO's four-part Weight of the Nation series, lays out the science of energy balance, the simple arithmetic of calories eaten against calories burned, and follows researchers testing which strategies actually help people lose weight and, harder still, keep it off. Doctors and public health researchers explain why sustained changes in eating and physical activity outperform any single diet plan, and why maintenance rather than initial loss is where most efforts fail. The film treats weight loss as a long-term behavioral problem rather than a product to be sold, walking through the evidence on what keeps people from regaining the pounds they've lost. It sits alongside the series' other episodes on the disease's causes and its effects on children, focused here on what individual and clinical strategies can and cannot do.