Nearly every lifter will eventually run into a situation where they have to take a break from lifting. Injuries, time, lack of motivation, and aging can all force you onto the sidelines at times. Most fitness addicts confront time away from exercise by asking one particularly horrifying question: how long does it take to lose muscle? In order to answer the question, it’s important to look at several facets of health.
Muscle Volume Plays a Role
Obviously, the more muscle mass you have, the more you stand to lose. If you maintain your size by hitting the gym five times a week, and you are rigidly adherent to your nutrition and macros, two or three weeks of inactivity might have more of an impact on your muscle tone and definition than volume. This would assume that you were in something like magazine-ready shape, however. Losing two weeks of physical activity when you are almost ready to step onto a bodybuilding stage will have a bigger impact than someone who is fit but not at extreme levels of leanness.
A 2014 study in Acta Physiologica stated that most investigations into muscle loss focus on periods of disuse starting at two weeks. The results show that most people will not experience an appreciable visual loss of muscle with two weeks of inactivity. However, the skeletal muscle fibers – collagen, tendons, fascia, and such – can show marked diminishment in only five days of disuse. At a cellular level, things start dwindling faster than the eye can see.
Your Energy Source
Many lifters eat as much as they do because their workouts fuel their appetites. When you finish a heavy deadlift or squat session, or you’ve been sprinting, your stomach feels like it has turned into a furnace. It might actually feel like you can’t get enough food inside you.
When you take a break from exercise, your appetite will not be the same. Therefore, you might reduce your calories without even realizing it, because you are not trying to fuel your work-induced appetite. Lowered calories lead to a loss of overall body mass, including muscle. If you stop working out but continue eating the same amount of calories and protein, you may not lose overall size, but your body composition will change as your muscle fibers change and shrink.
Most studies indicate that muscle atrophy typically begins between 2-6 weeks of disuse. There are variables, however, that alter the results. Someone who competes in marathons has a marathon-runner level of very lean muscle. Those muscles will be built of muscle fibers that are better suited to endurance, not power, and as such, their fiber composition will cause them to atrophy slower than the muscles of, say, a powerlifter, whose muscle fibers are built with regular practice at intense weights.
The answer to the question, “How long does it take to lose muscle?” is, obviously: it depends. The elderly lose muscle at a faster rate than younger fitness devotees, but that is no huge surprise. Interestingly, there seems to be no distinction between the rates at which males and females experience muscle atrophy. In general, all trainees will be safe to assume that they will experience some degree of muscle loss if they focus on that 2-6 week window cited by most studies. Keep in mind though, that a brief break from the gym can actually be beneficial in terms of rest, recuperating, and renewed motivation, but at some point, your muscles will start to dwindle, so getting back sooner is better, whenever possible.
One important thing to remember is that when you finally do go back to the gym, you probably won’t be able to pick up right where you left off. Even if you haven’t noticed an appreciable visible difference in your muscles, you have almost certainly experienced a slight loss of strength. Trying to go too hard, too fast, instead of easing back in, can set you up for injuries. The last thing you want to do is be forced to take another break as soon as you’re back in the gym.