A lot of thin people just have amazing metabolism and eat loads and just never put on, some just have medical issues so what goes in comes straight out, then there's the graser who nibbles often but doesn't take in many calories or ones that just don't eat much but loads of salads and if they have cake, it's just a taste lol, I absolutely love my food, I couldn't give anything up.
My issue is that I've always eaten big, even as a child but I was always running about and using energy, I started driving and continued to eat the same and not use much energy at all, I sit a lot and have become extremely lazy as the years go on, I'm sure there's something medically wrong with me as i'm always so tired, but when I went to my gp and had bloods, just said low vit D, that's all, I took the prescription and it didn't help at all, I take a fish oil vit and vit d in it, not as much as prescribed but just doesn't help, probably my thyroid no doubt, hopefully losing weight will help more anyway as i'll have less to carry around.