Current 20 y/o female college student here. I went from super skinny to BMI of about 23 in HS when I swapped distance running for soccer and didn’t adjust my eating. I wasn’t technically overweight according to my BMI, but I was not in shape. I always wanted to lose 5 or 10 pounds but never saw myself as fat, so I didn’t do anything about it.
Freshman semester of college, I put on only 5-10 pounds, but it was enough for me to finally change things. I have lost 20lbs since then and feel better and am running better than ever. My family didn’t ever comment on my weight directly, but always strove to help me get in better shape for track, which would’ve resulted in some weight loss.
Honestly, it took me getting fed up and disgusted with myself to make the changes I have. Food is addictive, and it takes some big lifestyle changes to make a difference. Also being on my track team helped a lot - I was tired and embarassed of being the “slow chubby one” on the team, and weight loss was a crucial part to getting in shape. I just made health and running fast my goal, losing weight came with that.
Weight loss is hard, especially when you’re living in a dorm and stuck eating at the dining hall - you have no control over the ingredients that go into your food, and there is immense social pressure to join in on junk food consumption. I didn’t really get a handle on my nutrition and health until I got off the meal plan and cooked for myself.
I suppose my advice is not to address it directly. I sometimes wish my parents had said something, but in the end, I think it’s best they didn’t. I lost a lot of weight in middle school since I was trying to run fast (but went too far with it) and that definitely scared my parents. A comment that might help isn’t worth the risk of helping push her over the edge into dangerous habits. I would definitely encourage healthy eating at home - cook healthy dinners, don’t keep too many sweets or snacks in the house. Get out for a walk or go to the gym as a family. Perhaps your pushing will cause her to realize that losing the weight is doable!