Raise a meat hook if you’ve heard this one: 

“If you don’t use your muscles, you lose them.” 

This is true, but it takes a lot more disuse to lose significant amounts of lean mass than most people realize.

Specifically, most research shows that you don’t begin to lose lean body mass until after two-to-three weeks of no resistance training of any kind, and then how much muscle you lose thereafter depends on how physically active you are, how many calories you eat, and how much protein you eat.

Bed rest, for instance, will result in far more muscle loss than even just engaging in everyday activities (not to speak of resistance training of any kind or amount), and restricting calories and protein intake will accelerate muscle loss as well.

These findings explain the results of a study conducted by University of Tokyo scientists, which had two groups of people lift weights for a total of 24 weeks.

One group trained continuously throughout the whole study, and the other group trained for six weeks, took three weeks off, trained for another 6 weeks, took another 3 weeks off, and then finished with 6 weeks of training. 

And despite the breaks, the latter group gained just as much muscle as the former.

Now, the intermittent group would’ve likely fallen behind the continuous group if they both kept up this way for months and years, but this experiment minimally indicates that the occasional extended training break won’t spoil your performance or physique. 

Your muscles will probably shrink some during the pauses, but that’s mostly due to a reduction in intramuscular water and muscle glycogen, a kind of carbohydrate that makes muscles look and feel bigger—substances that quickly pump your muscle back up once you start training again.

It’s also worth noting that while sometimes circumstances make any training whatsoever impossible, if you can do just one or two relatively difficult resistance training workouts per week (bodyweight training can even work, although weightlifting will be more effective), you can maintain most if not all of your muscle because it takes far less volume (⅓ to even 1/9, according to research) to preserve muscle than to gain it.

Lastly, if you simply can’t avoid muscle loss through detraining, something to pep you up: You’ll quickly regain whatever you’ve lost when you start up again for reasons described in this article. 

So even the “worst-case scenario” is more a matter of inconvenience than catastrophe.