BF has high sex drive

So my bf and I are moving in together and we've never lived together before or spent more than just a few days together. He had a super high sex drive but I don't. I've put on a lot of weight recently (damn you Mirena and Doritos) and that's one reason I'm not super about it but most of the time I'm not feeling up to it (not feeling good, not into it, etc). We do have sex every once and awhile but he's constantly wanting it. I hate the fact my sex drive has been going down so much. Any tips for my low sex drive or how to go about the awkwardness of living together?