Yes, the generation that lived through rationing is considerably healthier than ones born later - it's not for nothing that you occasionally see commentaries about how the subsequent generation will not live as long as their baby boomer parents
The generation that lived through rationing (which actually lasted until 1954 - 9 years after the end of the war) suffered from very poor health. They had rickets from lack of vitamin D and lacked vitamin C in their diets.
Their children, the 1950s baby-boomers, enjoyed a better diet and vastly improved health as more and better food became available, but money was still tight, so excessive consumption was rare. Cars were still uncommon so people walked or cycled and leisure time meant playing outside so their physical lifestyle was better too. They are the ones who are in their 60s now and will be living for another 20 years.
Their children are the ones who grew up in the 80s and 90s when takeaways, fatty foods and processed foods started to become the norm. When the TV went on at 7am and didn't get switched off until midnight. When people stopped volunteering to run sports clubs and brownies as 24/7 replaced 9-5 and people no longer had the time or inclination to contribute.
And in turn their children are the ones who really are beginning to show signs of very poor health, so much so that their life expectancy is predicted to be lower than that of their parents or grandparents. Sedentary lifestyle, no PE or sports clubs out of school, mums taxi on call 24/7, kids being driven 200 yards to school instead of walking. Parents choosing convenience over nutritional value when buying food.