I'm pretty slim and have been all my life - now 61. Only 5'1, and currently weigh around 46kg. But I am very small boned, which I think also makes a difference.
I've never drunk a lot but did enjoy a drink when I was younger, but found I just lost my desire for alcohol around age 40 or so. Now I drink maybe once or twice a month, and only a couple of glasses.
I do eat from scratch every day, and only eat red meat a couple of times a month. I also rarely eat sugar, although I do like a bit of dark chocolate now and again. I find I don't really like eating early in the day, so breakfast is very light maybe some bran with yoghurt or some wholemeal toast, and lunch tends to be a plate of little things that I fancy eating like a mix of almond, cashew and macadamia nuts, with fruit and some nice cheese, avocado, cherry tomatoes and cucumber and maybe some yoghurt as well. Main evening meal is often pasta based or rice (not particularly keen on potatoes) with 3 or 4 different veggies and usually fresh fish or a white meat. If I don't have fish or meat with my main meal I do use nuts to add protein and eggs as well. But, I don't stop myself from eating anything, so if I do suddenly get the craving for a big gooey cream cake I will happily eat one, but I guess I am just naturally moderate in what I eat. Fruit and cheese are my big go to snacks, and I find if I eat fried snacks like crisps or doritos (which my DH loves) I get headaches (possibly something to do with the additives?).
I'm pretty active, but not excessively so, but do walk regularly, garden and do dance classes as well as Tai Chi. But, like a PP, I am also a fidget, and tend to do a lot of moving around even when sitting. (Even now as I am typing this i noticed my feet and toes are wriggling 😂)