This is, quite obviously, a terrific article. One major quibble: your conclusion is rather circular. You assume a consequentialist utilitarian ethics, and then conclude, "Therefore, the optimal solution is to maximize the outcome under consequentialist utilitarian ethics!" I'm not sure it's actually possible to avoid such circularity here, but it does feel a little unsatisfying to me.

On top of this, your dismissal of the "personal development" issue is a bit hand-wavy. That is, it's one thing if I make a decision to go smoke crack - then the personal development required to get better is essentially penance for my evil decision. Likewise with obesity: I've sinned by getting fat, therefore, I must absolve my sins by getting thin. Just taking a pill would be like getting absolution without saying any Hail Marys, or some such. While I'm actually on your side on this point, this position does not logically bind us to go around getting kids hooked on crack so they can develop as people - they haven't sinned, so they have no penance to do.