How to retain muscle?

Just two things: eat enough protein and do resistance training.
1.2 to 1.5 grams of protein per kilogram of body weight daily.
A 60-kilogram person needs 72 to 90 grams each day.
One egg has 7 grams, a glass of milk has 8 grams, a palm-sized piece of chicken has 25 grams.
Distribute evenly across three meals, don’t save all the protein for the evening.
Resistance training 2 to 3 times a week, squats, resistance bands, seated leg lifts.
No need to go to the gym, you can do it at home.
Do resistance training first, then cardio; this yields the best results.
I am now focused on anti-aging and longevity medicine, and the core principle is:
If you wait until your bones are broken to come to me, it’s already too late.
Retain your muscles before they disappear—that’s true “preventive medicine.”
Every bite of protein you take now, every squat you do, is building your “independent walking” capital.
This investment is more worthwhile than any financial investment.
A medical doctor wrote this.