Still gotta start eating like a Buddhist monk.
I started eating right when I hit 48.  I can honestly say I feel great.  Just from good nutrition.  No more aches, pains.  Knees are great.  No more bloating or reflux.  I've had positional PVCs my entire life, and while I know they're there, I don't feel or notice them as often as I once did.  Cardiologist says I have the green light.
Key measures that drive my entire nutrition plan:
4700 mg potassium / 2000 mg sodium a day
4800 mg n-3/day at 3:1 ratio with n-6 (n-6:n-3)
420 mg magnesium a day
30/40/30 macros
30 g fiber/day
<15 g added sugar/day
Never ever ever eat a meal or meal component made in a factory
If I hit those marks each day, through real food and no supplements or vitamin pills, I know I'm eating healthy.  I don't really look at total calories, because if you're eating real food and hitting those marks you get stuffed pretty quick with veggies.  The only real supplement I take is a little protein powder in my oatmeal.