Is it good? What about emotional harm, possible destruction of a persons belief in their own self worth? How about a distorted perspective of body image? Sure, they my exercise, eat better, loose weight, but what if their idea of self worth is not based around their weight now? Believing if someone else believes they are over weight, their value as a person is less? You would hope that some one would be emotionally strong enough to over come such cruelty, but what is being at a healthier weight better if their ideas of self worth is damaged in such a way? Then if they were abused in such a way to cause them to loose weight, could that not then continue the cycle of abuse with that person then fat shaming others? It is the potential when one uses harm to curb another's behavior. But it really comes down to my point. Your justification to do harm to another was to change their life to how you think it would be best. But who are you to make that decision for someone else? It is their life, not yours, and by doing harm to their life, not to protect your own, but to conform their life to your will, you are in effect taking a position of ownership over that other life. I believe no one should attempt to own another, so your justification is false and the potential unintentional consequences (hoping they're unintentional) could far exceed any benefit they might gain from eating better(possibly worse) and exercising. This doesn't seem like good to me. The only justification for the harm comes from a subjective opinion, but based on incorrect or insufficient reasoning. Which makes the subjective position wrong and the value of the action bad.