Perhaps your anecdote does not qualify as a suitable counter argument. Is yours a normative experience? It is easy to lose weight in the sense that the solution is easily stated. Just restrict calories enough and weight will be lost. I suggest this is one of those things that is easy to say and hard to do. Isn't it akin to telling lifelong smokers, "Just stop smoking."? After all, if one simply doesn't smoke cigarettes then one will no longer have a smoking problem.

Can you see that perhaps your level of commitment is not possible for some people? Some people simply lack the willpower to do this.