Keith's weight issue can be solved just by changing his diet (we all know the drill - lower carbs for starters).
But I doubt it's what he really wants to do. We all know people that eat because it temporarily covers up other problems. I imagine having an ongoing battle with the brown recluse bite has taken its toll psychologically. Do a search on this-its unbelievable what damage that does.
Until he gets over that, I'll wager that all the fat talk, tough love, etc etc will have no effect.