First, I want to apologize for my knee-jerk response to you yesterday, because I realize now that although you said something similar, you did not make the categorical statement about never being able to add muscle while eating a calorie deficit. That was another poster in this thread.

I confess that your post, and the previous one about "blindly believing" the guy who ate a caloric ton for a month yet gained not a single pound hit a nerve. For so many years fat folks have been told by their doctors that they must be lying when they say they're not eating a lot, yet gaining weight. And all those low fat studies whose data never proves the low fat hypothesis? It must be because the respondents are lying, and not because the theory is dead wrong.

I had personal experience in this, by fighting with my own doctor over how much I ate. Which was between 1000 - 1200 VERY low fat/high carb calories daily - on which I grew ever fatter. At my highest weight, 225, I also had an incredibly unhealthy 53% measured body fat. It's amazing I'm still alive. By finally having the courage to ignore 'conventional wisdom' and switch to a high fat/low carb, much higher caloric intake, I not only lost the weight, I lost over 50% of that excess body fat.

Since almost none of us on this very forum know each other personally, we must take many of our correspondents here at face value unless proven to be untruthful. Otherwise, how could we believe anything we read here? So yes, I do believe that young man, who wrote so movingly and humorously about his struggle to consume so many calories was telling the truth. Why would he lie? Why would I not believe him? He was only proving the very foundation of the WOE the majority of us here live by: that calorie counts don't matter because a "calorie" cannot by itself spike insulin, and without insulin the body has no way to store any fat, no matter how many calories you eat. It has to be a carbohydrate calorie for that.

And if that is not true, Type 2 Diabetics all over the world would rejoice, because they would no longer have to take insulin. But of course it is true, because without insulin injections, a Type 2 Diabetic could eat 20,000 calories a day - and still die of starvation within months.

It is also sadly true that categorical statements are sometimes made in these forums, and they are rarely helpful in getting to the truth.

Perhaps if the question had been asked: "If you're eating a calorie deficit, then how are you building muscle?" - we could all have had an interesting conversation about the possible answer.

I've been thinking about that answer a lot. So here is what I suspect is happening in terms of my building muscle while eating a calorie deficit, when it's clear that muscle requires a lot of nourishment and support from our body to grow:

1: I am still 15 pounds from my 'goal' weight.
2: I still have more body fat (in certain places) than I would like.
3: By being a long-term low carber, my body now prefers to use fat, not carbs, for fuel.

4: Every time I greatly fatigue my muscles, that is, work them to complete failure - they need a lot of fuel/energy to recover. And by fatiguing my muscles regularly, my body knows to protect my lean muscle mass except for a last resort of starvation.
5: BUT - I am not eating enough calories to provide what those muscles and my body needs for repair.

6: THUS - More and more STORED body fat must be siphoned off on a daily basis, and turned into the necessary fuel/energy for the demands I am placing on my body.

If this hypothesis is correct, then the more my muscles build, the more stored body fat loss I should see.

And - eureka! - that is precisely what is happening. When I build muscle slowly (do traditional weight training, for instance), I lose body fat slowly. When I build muscle mass more rapidly, and more massively, such as with Slow Burn for instance, I lose much more body fat, and I lose it much more quickly.

ERGO: Far from saying that one cannot eat a calorie deficit and build lean muscle mass, I believe we may well be able to say that one way to quickly lose a lot of inches and body fat is by eating a calorie deficit while building muscle mass. The more overweight we are, and the more body fat we have to lose, the better this hypothesis will work.

And suddenly, what was stated as an absolute impossibility becomes a potential benefit!

And that hypothesis still allows for the reverse (no calorie surplus, no muscle mass gain) to be true - in some specific cases. Like -- being very skinny and having very low body fat, for instance. In that case, trying to add muscle mass while eating a calorie deficit would not only be difficult, it might well cause cannibalization of important tissue.

That's the kind of hypothesis I like.

Lisa