I run around 50 miles a week and swim 5, so if I didn’t eat plenty of carbs I would just crash. However, a long time ago I decided to stop second-guessing diet vs mortality. “Eat food^1^, not too much, mainly plants” - is still as valid today as it was twenty years. Perhaps more so.
Along with this you need plenty of exercise. That needs to cover:
aerobic exercise to increase your cardio endurance,
VO2max (short spurts of high intensity that elevates your heart rate to near maximum and leave you breathless),
Strength - weights or resistance exercise to work your major muscle groups, and
Stability - specifically for core muscles
Don’t smoke or take hard drugs, and if you drink alcohol do it in moderation.
That’s it - then you can sit back and relax knowing that you are doing the most you can to be able to enjoy a healthy life. We can’t always control how or even if we will arrive at old-age, but we can swing the odds heavily in our favor by the choices we make when we are young.
Food - something you grandma would recognize as edible. Generally if you can’t pronounce it easily it’s not food.