Just like muscle mass isn’t built overnight, you won’t lose it overnight either. Read more to learn about when to expect muscle loss and how to minimize it.

First, Some Considerations:

How quickly you lose muscle mass depends on a variety of different factors:
Training Age (i.e. how long you've been training for) and how much muscle mass you currently have
How much time are you planning on taking off from training?
Nutrition (i.e. calorie intake and protein consumption before, during, and after training break)
Concurrent activities (i.e. are you taking a break from the gym and planning to lay on the beach all day or going to hike a mountain)

Best Case Scenario

If you need to stop all forms of training (i.e. no strength training, walking, sports, etc.), you can still set yourself up for maximal success by:

Eating enough calories (at least consuming maintenance calories)
Eating enough protein (~1g/lb of body weight)

In this scenario, you will start to experience actual decreases in muscle mass after ~2 FULL WEEKS of inactivity

If you are able to remain active in any way, you'll be able to provide some stimulus to the muscle and may be able to delay actual muscle loss until ~3 weeks away from strength training. Keep in mind that's the best case scenario! If you're not eating enough total calories and/or aren't eating enough protein, then it's possible that you will begin to lose muscle a bit faster.

Remember, everyone's circumstances are a bit different. Two weeks is generally when muscle atrophy starts but it can happen a bit sooner or a bit later depending on your lifestyle. But don't freak out, the rate of muscle loss is slow! Just like you didn't magically gain muscle overnight, it won't disappear overnight either.

But I came back after a week off and I feel weaker…

This is normal! After a short training break (<2 weeks) you are experiencing the short term effects of detraining, which are mainly driven by neurological changes that occur when you stop or reduce your normal training load. Regular strength training leads to neuromuscular adaptations, improved synaptic efficiency, motor learning, and muscle fiber adaptations. Your brain and nervous system become more efficient at activating your motor units. When you take a short break from training, the opposite effects occur. Neural connections responsible for recruitment and coordination become less efficient, synaptic pruning may occur, and the rate of muscle protein synthesis can decrease.

These neurological changes happen faster than changes to actual muscle mass which is why you likely feel weaker when returning from some time away. But don't freak out, just as the neurological adaptations atrophy a bit faster than muscle, they also return much faster so you can expect to feel back to yourself after ~1 week!

I look deflated… how do you explain that?

This is also normal! You might feel "flatter" or less defined after a short period away from training, but this is not the same thing as actual muscle loss. Your muscles won't be as full after a period of inactivity due to intramuscular glycogen depletion, loss of muscle pump (i.e. increased blood flow and fluid accumulation), and decreased muscle inflammation.

Your muscles may not feel as full, but rest assured this isn't muscle loss. You'll likely get your pump back pretty quickly after a normal return to exercise.

Train with Moxie