Originally Posted by teaser

Diet is everything. A no protein diet, and you probably won't hold on to your lean mass for long. But months of bed rest won't do you any good, either.

Put one arm in a cast, it withers compared to the free, useable arm. Okay, stress of injury doesn't help. Suspend rats by their tails, shame on you, but now you know that their hind limbs will wither. Again, sort of stressfull. But both cases are consistent with deloading causing muscle loss, there wasn't a diet intervention.

Take somebody eating the exact same diet but not working out, add a reasonable workout--go excessive, IronMan or marathons, and increased oxidation of protein during the workouts etc. might actually waste lean mass--instead, two or three, half hour workouts, with weight or calisthenics or weight bearing yoga a week, and eating the same amount of protein, it's more likely you'll see increased lean mass or at least a positive nitrogen balance with than without the exercise. These observations are really freaking robust, I find it hard to believe we're even having the conversation.