Boyfriend lost sexual interest because of my weight...

My boyfriend and I have been together for 3 years and have had a healthy sex life for about 2 and a half years. I have gained 70 lbs since starting college and it didn't start to become an issue until the beginning of this year when I was told I need to start losing weight or I will be likely to develop diabetes. For several months my boyfriend told me he was tired or wasn't in the mood so he didn't want to have sex but about 2 months ago he finally told me the truth and said it's because of all the weight I gained. We have sex about every 2-3 weeks now (instead of 3 times a week) and I'm in the mood way more often than that. I don't want to break up with him because I don't think it's his fault but should I be with someone who isn't attracted to the body I have now?