Fat loss without Muscle loss?

[geo]

Most people believe that when you lose weight (calorie deficit) you are loseing a mixture of fat and muscle (lean tissue). The fat being good to lose and the muscle being bad to lose. The theory being that when losing weight, you will always lose some percentage of fat and lean tissue. So some people will do resistance training to try to spare muscle loss during weight loss. But what if you could determine a caloric deficit that would let you lose only fat and not lean tissue?

Here's an interesting study on how to maximize fat loss while minimizing muscle loss when dieting: Alpert SS. A limit on the energy transfer rate from the human fat store in hypophagia. J Theor Biol. 2005 Mar 7;233(1):1-13.

http://www.ncbi.nlm.nih.gov/pubmed/15615615

Basically, the researcher found that the most energy you can get from a pound of fat in a day is ~30 calories (thats rounding off and adding a conservative buffer) when you are in a calorie deficit mode. Supposedly, as long as you stay within this 30 calories per pound of fat in a day, you won't be burning any muscle tissue. Once you go beyond the 30 calories a day per pound of fat, your weight loss will be from lean tissue.

So for example, lets say you have 50 lbs of fat on your body. To maximize fat loss without losing lean tissue the maximum calorie deficit you would want is 30 calories x 50 lbs of fat or 1500 calories a day deficit.

As long as your calorie deficit is no more than 1500 calories a day then you will have maximum fat loss with no lean tissue loss.

So if your usually eating 3000 calories a day, you can go down to a 1500 calorie a day diet and spare lean tissue loss.

Of course, the lower your fat level goes the less calorie deficit you can have per day without losing lean tissue. So you need to recalulate your max calorie deficit every few weeks or so.

And yes calorie deficit can be from calorie restriction (i.e., diet), or exercise, or neat, or thermogenics or any combination of these.

To my mind its an interesting idea, but I wonder if the body is so simple and clean cut on when it chooses to use fat or lean tissue calories during a calorie deficit.

Hopefully someone can comment on this theoretical study...

[hazelrah]

So, does this mean Intermittent Fasting is a bad Idea? Seems like the way the energy is taken in and expended is not linear, but will fluctuate throughout the day. I'd expect when your energy needs exceed whatever level makes your body go to lean muscle mass at that instant will cause the loss, so I don't think it's possible to figure out exactly how to eat to make sure the new energy is being used instead of some other source.

But, if it's any consolation, I've been working on trying to find a way to avoid strength training for years.

Mark

[geo]

I have no idea. But if the study is correct, it would appear that any calorie restriction mode that restricts calories severely would not be the best weight loss technique since it may encourage loss of lean body mass. And in retrospect isn't that what most science says about weight-loss, that its better to lose weight at a slower rate than a faster rate?

Unfortunately, I cant read the whole study and gleening from what others have said about it on various sites, its almost purely a study based on mathmatical equations and calculations derived from data in other studies such as Dr Ancel Keys Minnesota Starvation Experiment.

As I said before, its an interesting study, the idea that there is some cutover point in calorie restriction that will maximize fat loss over lean body mass loss. But I'm not so sure that calculations like these can be applied to such a dynamic system as the human body. It may be frought with so many assumptions thats its meaningless or useless in practice.

Hopefully, someone like Jeff can speak to this...

[hazelrah]

Hopefully, someone like Jeff can speak to this...

I asked on Jeff's forum and some of the studies he listed lead me to believe that in practice there is no basis for believing that fasting would increase lean muscle mass loss. Some of them mention body composition specifically. He also pointed out that you enter ketosis when you hit certain levels, and in ketosis it's unlikely that that 30 cal/day/pound of fat claim holds.
https://www.drmcdougall.com/forums/viewtopic.php?f=22&t=51433


Interesting idea, though.

Mark

[geo]

Yeah been following your thread in Jeff's forum. And I agree, those studies are way to short. I was hoping he might comment on the study I posted, but at any rate what I've found in my own experiments is that even following a very strict MWL program. I never really even came close to hitting that 30 calorie supposed limit. So in my mind you would have to do some really crazy, severe calorie restriction to hit that, i.e., never a good idea. And there's a large body of work already available that shows you can lose weight and gain muscle while in a calorie deficit diet through a little resistance training. (Dr Ellington Darden has been showing this for 40+ years).

So while it seems a cool idea to believe there is some sort of hard number that might maximize fat loss and minimize muscle loss during "dieting" I think the real answer is the same as we have always known and talked about here....sensible diet plus sensible exercise plus sensible lifestyle over time...AKA: The McDougall Program