my grandma was a fat 80-something year old. But her whole life she was a thin shitlord nurse. We found out though that for years she had an eating disorder and would just drink booze instead of eating, and if she ate, she'd throw it up. So when she was put into a nursing home (because dementia and alzheimers) she started gaining some weight because she was getting 3 meals a day. She initially didn't gain much, she was still active, walking around the nursing home (she thought she worked there, and they got her a name tag and played along with it and everything) and helping, but when she was wheelchair-bound she gained pretty quickly because she was on medicine that made her hungry, she would forget she ate and she had snacks in her room fridge. At that point she didn't have much longer on the earth (lung cancer) and she couldn't have lost the weight before she passed (she hit smallfat status, so still was not a planet, just bigger than I had ever seen her) and the nursing home asked if we wanted them to cut back on her food and we said "You know what? She's going downhill as it is, just let her enjoy the cake." She was already so sick and not aware of her surroundings at that point that it wasn't worth trying to do anything else other than help her be comfortable and keep her happy.