If you are new to weightlifting or already have years of experience, you will likely build muscle at roughly the same rate when following the exact same workout program.

If you're a guy between 18 and 40 and you start lifting weights, whether you're new to it or have been doing it for years, you probably won't gain much more muscle just because you're experienced—but the people who’ve trained the longest (4+ years) still tend to gain the most muscle, so experience doesn’t always make a clear difference.

If healthy adult men do resistance training for more than two weeks, they will reliably gain about 1.5 kilograms of muscle. This shows that lifting weights is a very effective way to build muscle overall, no matter how you measure it.

If you're a healthy man between 18 and 40 years old, your starting height, weight, and age won't really change how much muscle you build from working out. Basically, everyone in this age group tends to gain muscle at roughly the same rate when they follow the same training plan, no matter their body size.

People who’ve never lifted weights before gain muscle much faster than those who’ve trained before—even if they do the same workout.

If healthy guys between 18 and 40 lift weights regularly for at least two weeks up to a year, they typically gain about 1.5 kilograms of muscle—no matter what kind of weight routine they follow.