My 80s childhood diet
Cereal with milk/ yoghurt or dry. I have always hated milk (turns out milk hates me and triggers IBS) or toast.
Traditional school lunch with mash/ plain boiled potatoes and two-veg with a small dessert and small cup of water.
Dinner: spaghetti bolognese if DM was feeling motivated (using schwarz packet mix). More likely to be Fray Bentos pie/ faggots/ Dalepak "steaks" with tinned potatoes and two-veg. Probably tinned. If she really CBA, a tin on toast. Worse case scenario tinned tomatoes on toast which meant a long night until breakfast because plain tinned tomatoes are gross and they ruined the toast making it too acidic and soggy to eat.
The only vegetables I ate were carrots and mushrooms. Mainly because I hadn't met a vegetable that hadn't been boiled into oblivion.
Very few snack options avaliable. Certainly not a routine between meals. I wasn't allowed to take "tuck" to school or have 10p for the tuck shop. Some access to apples/ oranges/ bananas. Strawberries if they were in season. We grew grapes so again, if they were in season. One house had fruit bushes/trees from the the previous owner so there were seasonal fruit pies on Sundays. Triffle was another Sunday treat.
I was always the smallest in the class and very slightly built. But generally pretty healthy.
I wasn't particularly active- hated sports and running, but did a bit of gymnastics and dancing. I did a lot of pottering around though, so there was a lot of gentle movement rather than "exercise:
DM had been a war child so spent the majority of her youth with rationing and her mum was no great cook/ food enthusiast either. In the 60s, Twiggy had the aspirational look so food had always been an uninspiring necessity to be done a few times a day and wasn't a pleasure. In her credit, her mother made it into her 90s and she's well into her 80s, not without niggles, but the essentials for survival are all functioning fine. Where their diets and lifestyles have likely been negatively influential is on osteoarthritis.
I've come out of my childhood with a healthy attitude to nutrition and exercise and am on good form for my age range. I loved getting to university and getting more experimental with food with the widened choice of the late 90s.
I suspect there is a difference between 80s processing of food and current processing. Bread certainly lasts longer without going mouldy now so those kinds of basics have increased in levels of processing. Some ingredients like food colourings have been removed in the UK, but there are more additives such as preservatives and emulsifuers. More foods are modified to be low fat/ sugar which means added additives to make them behave the same way. The range of food/ drink containing artificial sweeteners has also increased significantly. Supermarkets are bigger, but it's not the staple, fresh foods that have increased.
Children were leaner and more active with a better balance of nutrition to their activity then. What has improved is a greater range of fresh veg/ fruit year round (great for more selective eaters like I was), but good quality basics are dearer and it's easier (and cheaper) to have a lot more ultra-processed foods as staples. Snacking culture, eating out and takeaways have increased and it is much easier to eat a surplus of appealling foods now.
There were still a lot of children having traditional diets in the 80s and living healthily on it.