This "dont cut out a food group" business. What about all the gluten free and vegetarians?
Do you know what a food group is?
Vegetarians and people who eat gluten free aren't cutting out food GROUPS but some food types.
Vegetarians still eat protein
Gluten free still eat carbs
Portion creep is definitely a factor, said on here several times before my mother is still using the dinner service she had since the 70's, I have a modern but not outsize one just cheap basic white, my side plates are nearly the size of her dinner plates and my 70's designed kitchen the cupboard doors can't shut! Things like this definitely have an effect on serving size. I try to remember and act accordingly but not easy.
I also don't think it was common to spend the evening eating carbs/sugar in front of the tv, on top of 3 meals per day plus snacks we did and from what I saw/heard so did my peers
Breakfast - cereal or toast, orange or apple juice, occasionally fry up at weekends or holidays for a treat
Mid morning - snack at school you took with you, usually packet of crisps (admittedly much smaller then) or chocolate bar or pack of sweets like chewits
Lunch - school dinner (I was very lucky ours were lovely home cooked things like shepherds pie or stew with veggies and potatoes) main plus pud (and I mean pud usually steamed sponge pud with custard and wouldn't have been low sugar or low fat either) or packed lunch (which would horrify now - cheese or ham or even shiphams paste sandwiches, crisps, yoghurt - wouldn't have been low fat, portion of fruit, penguin type biscuit, full sugar squash in a plastic flask)
After school - in our house we actually differed to a lot of peers here, mainly due to lack of money and cultural/nationality (scots) so we tended to have home made soup (mum always has a pot on the go - when she doesn't we know somethings up!) with buttered white bread or a roll, sometimes a "jammy piece" a jam sandwich made with a thick layer of butter too.
Dinner - almost always home cooked from scratch, basic fare like chops, steak and kidney pud, stews etc meat and 2 veg really and not exciting veg, I don't think my mums ever cooked anything but carrots, cauliflower and greens! Also almost always potatoes - even with pasta when that started to be a thing! Pud every day too - again proper pud sponge or cake with custard maybe ice cream in summer washed down with full sugar squash or milk
Supper - not till high school age as we weren't "up" late enough until then but tea (with full fat milk and sugar) or hot chocolate mostly toast always buttered heavily white bread with a variety of sweet and savoury toppings or sometimes something like malt loaf or ginger bread
All 3 of us very slim, active, healthy kids.
At the time I thought mum was fat, but actually she was never bigger than a 14 and usually a 10-12, dad was rail thin still is.