Jokes at her expense, teasing, distancing sexually? Those are all things which will make her feel poorly about the dynamic and the mans affections, and in-turn hers to him; the conditions of the relationship. Not to mention, they are subtle ultimatums.
Through all those covert actions to the greater objective, shes not going to just subconsciously understand “oh I have to be my best self for him” and then all of a sudden be in victoria secret shape lol. It’s just going to increase negative drama and unideal tension.
The best thing to do would be get himself in excellent condition; worry about himself, and through this the woman would be much more aware of herself and personal short-comings. And when she opens up about working out, health, her weight gain - through her own volition - that’s when you have the ‘hard conversation’ about your desire towards her ‘new self‘ and areas which you personally find attractive — It’s letting her step in to the difficult conversation herself. In to your frame, as opposed to the man saying ‘I need you to be this way for me’ Through the guise of teasing and pokes.
To get anyone to do anything, it has to be their choice. Otherwise you’re just saying how things should be, and people naturally want to rebel against that for the sake of retaining autonomy.
So you don’t kick in the door. You simply influence the person to unlock and slowly open the door.
if you get yourself in great shape and change your life for the better, and she is gaining more and more weight, only going down hill, you’re simply incompatible for the future based on values. Different trajectories.
But you would naturally distance yourself from her during this time based on your natural loss of attraction, rather than unnaturally withholding sex to get her to change.
The only goal a man should have in a relationship is the same as what it should be when he is single - to exponentially increase his value. When you’re doing this, the woman you’re with will naturally want to be in alignment. And if they aren’t? You simply move on because you can sense the lack of harmony. Nothing a man does should be because of a woman. Changing her behaviours or withholding sex is just a loss to your independence and are petty games.