Is it really true that you can't gain muscle on a deficit ?

From what I read, increasing muscle mass is more benefitial to weight loss than pure cardio due to muscle needing calories to exist basically.

Part of that isn't necessarily putting on lean muscle. There are arguments (I don't have the studies they're based on at hand, so I'm not going to state anything as a fact) that after strenuous weight training, the metabolism can be heightened for up to, I believe, 39 hours or more. While cardio does spike your metabolism, it's for a much shorter time.

Everything I've read says that no, you can't gain muscle mass while on a deficit. Your body is not getting enough energy to live, therefor it has to pull energy from it's stores (usually fat, but sometimes it'll take muscle as well). These stores are precious and important. It doesn't like to use them. It certainly isn't going to use them to build muscle tissue.

Uh, no, it can't use fat to build muscle tissue, because muscle tissue isn't made of fat, it's made of proteins... this is not about thermodynamics (energy in / energy out). That would be nice, but your body isn't a closed system, and not all calories are treated the same way by your body. This is really about biochemistry, so it's much more complicated & messy. But if you give your body the tools it needs, the proper nutrients, that's how you can build your muscles.

My doctor has a fancy machine that calculates body composition. He tested me back in March (when I began) and every month since. I've consistently lost fat & water weight, and gained about a pound of muscle a month.

Here are some interesting articles:
http://danceswithfat.wordpress.com/2011/06/02 /calories-incalories-out-science-says-no/
http://www.proteinpower.com/drmike/low-carb-library/why-we-get-fat/

The point of resistance training in a fat loss routine really isn't about creating a calorie deficit. That's the job of your diet (and cardio if you choose to do it.)

The point is to retain existing muscle mass (or in some specific cases add to it) help with functional day to day strength, increase bone density, preventing osteoarthritis, inhibiting sarcopenia, helping to reduce day to day injury, helping with balance, elevating mood, improving CV capacity and generally looking good naked when your diet has stripped away excessive levels of body fat.

If your mindset when incorporating resistance training into your fat loss routine is centred around creating a calorie deficit you probably misunderstand its primary purpose.

Everything I've read says that no, you can't gain muscle mass while on a deficit. Your body is not getting enough energy to live, therefor it has to pull energy from it's stores (usually fat, but sometimes it'll take muscle as well). These stores are precious and important. It doesn't like to use them. It certainly isn't going to use them to build muscle tissue.

Uh, no, it can't use fat to build muscle tissue, because muscle tissue isn't made of fat, it's made of proteins... this is not about thermodynamics (energy in / energy out). That would be nice, but your body isn't a closed system, and not all calories are treated the same way by your body. This is really about biochemistry, so it's much more complicated & messy. But if you give your body the tools it needs, the proper nutrients, that's how you can build your muscles.

My doctor has a fancy machine that calculates body composition. He tested me back in March (when I began) and every month since. I've consistently lost fat & water weight, and gained about a pound of muscle a month.

Here are some interesting articles:
http://danceswithfat.wordpress.com/2011/06/02 /calories-incalories-out-science-says-no/
http://www.proteinpower.com/drmike/low-carb-library/why-we-get-fat/

He didn't say use fat to build muscle directly. He said use the fat as the energy to build the muscle. Which we all know occurs when we're in a caloric deficit.

I believe that people want desperately to lose weight FAST so as to beat their loss of willpower to the finish line. Yes, I know there's no finish line if you actually intend to get / stay healthy but IMHO your willpower DOES have a finish line. And one must achieve results worth while discussing BEFORE the will to do the work dies.

Very well said.

I think this ties in to people being well educated/informed and having appropriate expectations. Losing weight is not the same as getting healthy, and the scale is not the determining factor in success.

As to your original question... as others have said, you can make very minor gains while on a deficit (this makes some assumptions and is dependent on the size of that deficit, body type, etc).

Protein biosynthesis and mucscle growth happens at its own rate regardless of caloric surplus or deficit, but there are tons of factors involved. Too many to get too in depth.
The maximum size of skeletal muscle you can have (without steroids) is directly related to the overall mass of your skeletal frame. The further you are from that maximum size, the easier it is to build muscle. The closer you are, the harder it is. The only reason you would need a calorie surplus is if you're already pretty big and trying to build more. Take, for instance, someone who breaks their leg. When they get the cast off the leg muscles are small and atrophied and have to be rehabilitated. I've never heard of people being prescribed a calorie surplus and crates of muscle milk to rebuild the muscles in your leg, nor is it likely that you will never be able to walk again if you're on a calorie deficit. That's just silly.
So what happens to all the protein you eat if you eat 1 calorie less than your maintenance calories? Does it magically vanish? Wouldn't you die from a cold since you could no longer produce antibodies? How much extra protein could you possibly get from a 100 calorie surplus? Enough to turn 450 grams of protein into muscle tissue? The math doesn't add up.
If you can't gain muscle on a 'modest' calorie deficit then you're doing something wrong. Yes, it will be a bit slower, but not as much as you might think.

~~ You CAN gain muscle mass on a deficit. How do I know this? I was part of a university study that literally measured *specifically* my muscle growth over a 6 week period. ~~

Protein biosynthesis and mucscle growth happens at its own rate regardless of caloric surplus or deficit, but there are tons of factors involved. Too many to get too in depth.
The maximum size of skeletal muscle you can have (without steroids) is directly related to the overall mass of your skeletal frame. The further you are from that maximum size, the easier it is to build muscle. The closer you are, the harder it is. The only reason you would need a calorie surplus is if you're already pretty big and trying to build more. Take, for instance, someone who breaks their leg. When they get the cast off the leg muscles are small and atrophied and have to be rehabilitated. I've never heard of people being prescribed a calorie surplus and crates of muscle milk to rebuild the muscles in your leg, nor is it likely that you will never be able to walk again if you're on a calorie deficit. That's just silly.
So what happens to all the protein you eat if you eat 1 calorie less than your maintenance calories? Does it magically vanish? Wouldn't you die from a cold since you could no longer produce antibodies? How much extra protein could you possibly get from a 100 calorie surplus? Enough to turn 450 grams of protein into muscle tissue? The math doesn't add up.
If you can't gain muscle on a 'modest' calorie deficit then you're doing something wrong. Yes, it will be a bit slower, but not as much as you might think.

New muscle tissue beyond someone's current body composition requires more energy to be taken in then burned. I'm not saying very minimal gains can't be made by someone that is morbidly obese or someone that is brand new to resistance training.

You ever see men at the gym that go there for months upon months, year after year and never get any bigger? Do you ever wonder why? If people could gain pounds of lean muscle mass on a calorie deficit then almost everyone in the gym would have very little bodyfat, be ripped and have loads of muscle mass. This is not the case.

Please do some real research about the subject before you start spreading false information.

Do you even know what protein biosynthesis means?

I give up lol

I sent you a message considering I didn't want to type out my story on here. I'm genuinely confused and would like your take on my results from the study I was in. Thanks!!

Protein biosynthesis and mucscle growth happens at its own rate regardless of caloric surplus or deficit, but there are tons of factors involved. Too many to get too in depth.
The maximum size of skeletal muscle you can have (without steroids) is directly related to the overall mass of your skeletal frame. The further you are from that maximum size, the easier it is to build muscle. The closer you are, the harder it is. The only reason you would need a calorie surplus is if you're already pretty big and trying to build more. Take, for instance, someone who breaks their leg. When they get the cast off the leg muscles are small and atrophied and have to be rehabilitated. I've never heard of people being prescribed a calorie surplus and crates of muscle milk to rebuild the muscles in your leg, nor is it likely that you will never be able to walk again if you're on a calorie deficit. That's just silly.
So what happens to all the protein you eat if you eat 1 calorie less than your maintenance calories? Does it magically vanish? Wouldn't you die from a cold since you could no longer produce antibodies? How much extra protein could you possibly get from a 100 calorie surplus? Enough to turn 450 grams of protein into muscle tissue? The math doesn't add up.
If you can't gain muscle on a 'modest' calorie deficit then you're doing something wrong. Yes, it will be a bit slower, but not as much as you might think.

New muscle tissue beyond someone's current body composition requires more energy to be taken in then burned. I'm not saying very minimal gains can't be made by someone that is morbidly obese or someone that is brand new to resistance training.

You ever see men at the gym that go there for months upon months, year after year and never get any bigger? Do you ever wonder why? If people could gain pounds of lean muscle mass on a calorie deficit then almost everyone in the gym would have very little bodyfat, be ripped and have loads of muscle mass. This is not the case.

Please do some real research about the subject before you start spreading false information.

Do you even know what protein biosynthesis means?

Yes I know what it means.

Do you know what "you cannot build new tissue beyond your current composition without energy" means?

(we can do this all day long..)

Then please describe.