Is this muscle or fat loss?

[Mike Pants]

I know, if I'd been keeping accurate measurements, I wouldn't have to ask, but...

It's been a little over two weeks since I've been able to work out because of a leg injury, and in that two weeks, I've lost about 8 pounds, from 171 to 163. This seems excessive, especially for a period of no working out, so I'm starting to worry that this is muscle losing mass rather than straight fat loss.

So the question is--how quickly does one lose muscle mass? Once someone stops lifting, at what point do gains begin to reverse?

[Brah]

If you had previously been working out regularly then there is a decent chance you have lost some muscle. I've heard that muscle atrophy will happen in a week or two, but I don't have an exact figure for you. If you are eating less than you're burning and you're not working out you are bound to lose some muscle.

Don't worry too much, the amount of muscle you lose isn't as drastic as you might think, and thanks to muscle memory you can gain it back pretty quick.

[Waldo]

Your muscles probably dumped a lot of the extra water they were holding on to to power your energy systems.

You'll lose it fast if you stop working out, and gain it fast when you start again. Kind of a semipermanent pump that comes with regular strength training.

The suppliment creatine enhances this effect (among the things it does).

You probably did not lose much, if any, actual real hard earned muscle tissue.

[Mike Pants]

Ah, did not know this about water retention. Cue the "The More Your Know" star.