The reason is that doctors and pharmaceutical companies are also for profit, meaning they make money selling you treatments. This puts them in a position to use your condition to exploit both you and the company. The insurance company is balancing the cost of your preferred treatment versus the cost of other treatment and the benefits. You can work with your doctor to build a documented record of attempting to lose weight- see a nutritionist, start seeing a therapist for your food addiction, start going to weight loss meetings, exercise therapy for the morbidly obese, etc. These will also be helpful by themselves, because those drugs are only temporary. Like weight loss surgery, people regain the weight when they don’t do the work to address the underlying issue.