I have no idea if he will be successful in a business sense. However, I do think it is unlikely that he will help many people. The economists at Marginal Revolution point to research indicating that betting on weight loss is generally ineffective: people don't lose the weight: http://www.marginalrevolution.com/marginalrevolution/2010/09...

Ultimately, if you're taking money from people with the expectation that the vast majority of them will fail, well, that doesn't seem like the kind of business that will generate lots of referrals from happy customers. People generally don't like to share their personal failures. Beyond that, focusing on weight per se seems problematic from a public health perspective. It is extremely difficult to lose weight but also not strictly necessary for health benefits. If you can run 10 miles in an hour, it really doesn't matter what your weight is, and the ability to do is a much better predictor of future health.