BigBallBellyGirl:
Strongly agree with Munchies. My husband is a dom, but he's my husband and partner first. Since I had heart surgery last year, he's completely adjusted the way he engages with this kink. Instead of feeding and stuffing me, he's gotten into a lot of belly play and other activities. That's because makes decisions with his brain and his heart, not his dick. If the opposite were true, that's when an ethical question would be in play.
My partner and I do something similar. I'm his domme, but I fully support his weight loss. (He's struggling a bit, but since we are moving in with each other next year, he'll have more support in his weaker areas.)
Sometimes, I still feed him, but it's normal-sized portions.