To maintain muscle after 40, eat at least 0.7 grams of protein per pound of your goal body weight and lift at least twice a week.

That's the floor. Want to build? Aim for 1 gram per pound. On a crazy week, don't dip below 0.7.

Starting around age 30, the average adult loses 3 to 8 percent of their muscle every decade. The slide speeds up later.

Muscle is a rental, not a purchase. Stop paying rent and the landlord takes it back. Protein and lifting are the rent.

Maintenance mode is cruise control, not park. Your foot is still near the pedal. You're just not pushing.

One catch on injuries: that's the worst time to cut protein. When lifting isn't there to protect your muscle, protein has to carry more of the load. Stay near the higher number.

Move 1: Know your floor. Goal weight times 0.7. For a guy aiming at 190, that's 133 grams. Put it in your phone.

Move 2: Two full-body sessions a week. Thirty minutes each. Goblet squats, push-ups, dumbbell rows, Romanian deadlifts, 3 sets apiece. Keep the weights heavy even when the sessions get shorter. Research on detraining shows intensity matters more than volume for holding on to muscle.

Move 3: Protein first, even on bad weeks. The drive-through still sells grilled chicken. The hotel breakfast still has eggs. A bad week isn't an excuse. It's a menu problem.

Studies on trained lifters show strength holds up well through about three weeks off. And muscle you've built before comes back faster than it took to build the first time.

A little less. But after 40 the gap is smaller than you'd think, because your muscles need a bigger dose per meal just to respond. Treat 0.7 grams per pound as the floor, not the goal.

Not for long. Protein is the building material. Lifting is the reason your body bothers keeping the building. Walking is great for your heart. It won't hold on to your muscle.

I'm not a doctor. If you have kidney disease or another medical condition, check with yours before changing how much protein you eat.