When you lift weights, your body’s protein-making response doesn’t change much from week to week — but it’s very different from person to person.

People respond to weight training in wildly different ways—some grow muscles a lot, others hardly at all—and those differences between people are about 40 times bigger than the tiny differences you’d see if you trained one leg harder than the other in the same person.

Your muscles make more protein when you start lifting weights, but after a few weeks, that boost fades — even if you keep lifting harder — no matter if you use heavy or light weights.

Lifting weights makes your muscles start building more protein right after the workout, and mixing up your routine a little bit gives your muscles a tiny extra boost right after lifting—but in the long run, both routines build about the same amount of muscle.

Lifting weights at a challenging level makes your muscles build more protein, and this boost happens just as much in arms or legs that are used to exercising as in ones that aren't.

When you start lifting weights, your muscles build new protein faster in the first week than they do after 10 weeks, even if you keep training.