As you said here, a girl is willing to lose weight for a boy. Is it love? For me, it actually counts, because in my opinion, the power of love is great. If you like someone, you will make some changes for him, which is normal.
Actually, let's take a friend of mine as an example. He used to be a very fat boy. When it is heavy, it finally reaches 200 kilograms. But when he was in college, he met a girl he liked, and the girl told him that if he could reduce it to 150 kg, he would stay with him, which was too happy for an obese person, so he went out to exercise every day and went running with me. With his continuous efforts, after half a year, he finally reached about 160 kg. In fact, that girl didn't end up with him, but in my opinion, it's because the power of love inspired him, because you can't lose weight for no reason or because you are a very motivated person. I think this is also a sign of love, whether you are a boy or a girl, if you are willing to lose weight for one person.
In fact, the expression of our love is unique, and there are many forms, so each of us has a different expression. But in my opinion, if a girl or a boy is willing to change some of her bad habits or change her figure for you, that is the performance of loving you.