Diet and obesity are interesting when compared to the 50s/60s. I remember fat people then. My grandma and her friends were well padded and many of my schoolfriends at 11+ were lumpen and so were many work colleagues in the 80s. I think society has become more polarised and there are proportionately as many very thin people as there are very fat people.
I recall food, and good food, being plentiful. We never had bread and butter on the table as so often mentioned on this thread and my mother always said that was what poor people did when there wasn't enough meat. We had big dinners but didn't snack although coukd have. We also always had a jug of water on the table at mealtimes.
My parents were adventurous and were eating Italian and French food occasionally and curries. All home made. We rarely had convenience food, sometimes a lasagne from M&S. I recall my mother scoffing that many people would probably have just a small piece and serve it with meat and two veg.
Like others, sweets and squash were far more freely available and I recall Perrier Water being regarded as marketing genius - getting people to buy fizzy water from a green bottle.
My mother watched her weight and my grandma was always unsuccessfully dieting. My mother had a digestive biscuit for breakfast and two ryvita with cottage cheese or a piece of cheese for lunch and still does. She's hated the needle on the scales reaching 8 for her entire life.
The late 70s I think saw a switch to more wholemeal food with restaurants like Cranks and the influence of Rose Elliot. I have no recollection of Quiche before about 1975.
DH whose mother hated cooking was raised on cheap and convenience food and she was very stingy and counted everything. There was no need whatsoever for the meanness. FIL was rigid and they delighted in saying they would eat anything and in the next breath FIL didn't like: garlic, cauliflower, pasta, mushrooms, chicken or shellfish/fresh fish. MIL and FIL were exactly the same ages as my parents.
MIL now has tremendous trouble with her bowels which I am convinced relate to the decades of packet food. To this day, DH prefers white bread, likes a cheeky slice with his dinner and I sometimes find a Mars wrapper in his pockets because sweets were as rationed as the food.
A big difference is wine. It was drunk at meal times on special occasions and never gratuitously. My parents and grandparents had a G&T or Gin&It before a meal and possibly a nightcap, but wouldn't ordinarily have had wine open.
My parents and grandparents travelled which I think made a difference to their approach to food and my gf and father were European.
Perhaps because we were quite well off, I never recall either my mother or grandmother not having a fridge and both had freezers by the very early 70s, probably before. I also remember my mother having a Kenwood Chef as a tiny, and a liquidiser. She never, ever baked bread and made a cake once a flood. We had a good friend called Mr Kipling and usually had a box of cream cakes from the bakers once a week. I think that was unusual. Whenever my father went to London he always brought home baked (cakey) cheesecake from Kossoffs which had sultanas in it. I have never regarded the American disks with processed fruit on top to be cheesecakes!