Not attracted to my boyfriend anymore

When my boyfriend and I met 2 years ago, he was in very good shape and regularly went to the gym and cared about his health. However, the past 6 months or so he has put on about 30 pounds. He no longer prioritizes going to the gym and eating healthy. I've tried hinting at him and even offered working out at home with him, but nothing's helping. We used to have sex at least once a day, but since he's gained the weight I'm less turned on by him. I try really hard, but I'm just never into it anymore. We have sex about once a week. I'm more horny than ever because of the lack of sex but once I start getting sexual with him I get turned off. I don't know what to do, because I love him more than anything and don't want this to be a problem in our relationship.