The friend does not have trauma. Overweight does not have trauma either.
More importantly for overweight advice, it does matter whether you know and really are expert or whether you base advice on latest pop article or a random dude in gym theory.
You can comfort without being enabler. Don't give money to spender, but listen and be friend. (Or don't if it is harming you). Your impulsive friend will not magically become less impulsive just because you had lecture anyway. That is not how it works. He will need way more effort and support and will take long time to change - but only if he wants it.
More importantly for overweight advice, it does matter whether you know and really are expert or whether you base advice on latest pop article or a random dude in gym theory.
You can comfort without being enabler. Don't give money to spender, but listen and be friend. (Or don't if it is harming you). Your impulsive friend will not magically become less impulsive just because you had lecture anyway. That is not how it works. He will need way more effort and support and will take long time to change - but only if he wants it.