When people new to weightlifting don't eat enough calories, they actually lose muscle in body parts they aren't even working out. But if they eat enough food, their muscles stay the same size even in those untrained areas.

Doing more sets in your weight workouts might actually make you gain less muscle—each extra set could slightly reduce your muscle growth, so more isn’t always better.

If you lift weights more each week for each muscle, you’ll likely gain more muscle size—studies show about 3.9% more growth compared to doing less.

If you take a one-week break from lifting weights—even if you’ve been training hard—you won’t lose or gain noticeable muscle in your legs, and taking short breaks like this won’t hurt or help your muscle growth.

Higher weekly resistance training volume leads to greater muscle hypertrophy in trained individuals.

If you're a guy who lifts weights, eating a little extra—either 5% or 15% more calories—probably won't help your quads or triceps grow more over 8 weeks compared to just eating enough to maintain your weight.