No sure if my boyfriend is attracted to me

We’ve been together four nine months now talking for almost a year , there is talk about marriage trips planned ahead we’re very involved in each other’s family and socia life . Today post dinner with his dad I said I’ve decided to get a gym membership, im a bit thinner then when we meet but still not super skinny I’m what you would call slightly curvy i have a butt and big boobs , I’m about 170 cm on 74 kg not huge but not small either . Post dinner when I said this he said how beautiful I will look if I was 50-55 kg and I took it to heart . Now I feel like his not really attracted to me I know his ex was very slim . He claims it was a joke and that he loved me and my soul and who I am and claims that why would we have so much sex if he wasn’t attracted to me (we have an amazing sex love very active and open and we have sex at least once a day or twice )but this made me feel very emotional, why would he even joke about that . I’m feeling devastated. Am I that fat and unattractive? I’m feeling devastated