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Does Muscle Mass Really Help Fat Loss?


#1

Every so often a new theory on the best way to improve body composition does the rounds. Currently strength training seems to be the holy grail.

The theory is that the more muscle you have the higher your resting metabolism. So if you increase muscle mass you burn more calories even when you are resting.

Is this true?

I'd always assumed it to be. A discussion on the T-Nation fb page got me thinking and researching and I'm beginnning to think the muscle mass makes very little difference.

Increased Resting Metabolic Rate Caloric Burn
Apparently, the majority of our RMR caloric burn comes from function of the brain, heart, liver, kidneys, and lungs. Skeletal muscle only accounts for 20-25% of resting metabolic rate. One pound of muscle burns around 6 calories per day more than one pound of fat. Fat burns 2 calories per day.

So, say you gain 5 pounds of muscle then you'll burn an extra 30 calories per day at rest. If you started out needing to loose 14 pounds you would also loose 9 pounds of fat to reach your goal. That would reduce your RMR caloric burn by 18 calories per day. The net result of that 9lb fat loss and 5lb muscle gain would be 12 calories extra burned per day.

Strength training doesn't burn many calories. So if you're doing predominantly strength training you won't be burning much while you're training either.

Assuming the above is correct (I can share links to my sources if that's OK with the admins?) what, if anything, is the benefit of strength training when it comes to fat loss?

I have some thoughts on this - based upon my own experiences (because I DO think strength training plays a part). Just wondered what others thought?


#2

I often wonder about this as well and have a few ideas (possible bro science) as to why and to what extent strength training plays.
Firstly as you said muscle burns more calories than fat, although not much, the losing 9lbs of fat and gaining 5lbs of muscle would only yield a resting calories burned of just over 1lb of body fat a year, in other words very little.

But then that extra 5lbs of muscle will actually do far more than just burn a small amount of calories extra a day at resting rate. Firstly with that extra 5lbs of muscle you should be lifting more weight than without it, and in doing so you will burn more calories when actually training. Secondly and this is one I'm not too sure on is the whole oxygen debt thing (think that's the right term), so that number of calories burnt you stated is muscle at rest, but hours after a workout your muscles will still be recovering and burning more energy than they would 'at rest', an idea similar as to why HIIT training is recommended by so many is that one of its benefits is the oxygen debt it produces. Again take this with a pinch of salt as I am definitely no expert and this is just me theorizing.

Your statement that strength training does not burn many calories I would say isn't entirely accurate, yes it may not burn as many as doing that same amount of time spend doing cardio or circuit training etc, but it will still burn a fairly large amount of calories, especially if you're doing big heavy compound lifts, the amount of energy you have to expend is pretty huge, just look at how you feel after doing some heavy singles, doubles or triples with squats or deadlifts with 80-90%, I for one find it wipes me out pretty good.

Lastly, and more of a personal point, is that I would far prefer to do strength training than cardio, which in itself makes it a far better workout as I therefore approach it with more intensity as well as being far more likely to actually commit and perform said workout than skipping it with some pathetic excuse.

Just my take on it, but as I said, I am no expert so this may not be all totally true.


#3

I think you're right about your first point - that stronger muscles let you work harder so you'll tend to burn more calories when you are active. But I don't think that's the whole story because I notice improvements too quickly - my muscle strength won't have increased enough to let me work hard enough to explain the improved body composition. I do think there's something else. Is it increased Growth Hormone Production? Certainly big, whole body exercises is what I feel gives good results. If I broke it down into lots of little exercises I don't see any benefits. But the studies apparently show that there is no significant 'afterburn', so if Growth Hormone is helping it would seem it's not because it causes a higher calorie burn.

The point about muscles still recovering and burning more energy than they would at rest - well, apparently (according to what I've read today which may or may not be true) - that afterburn is insignificant and reduces the fitter you get. See the other thread I just posted regarding this:

http://tnation.T-Nation.com/free_online_forum/sports_body_bigger_stronger_leaner/does_high_intensity_training_help_with_fat_loss

I was wondering whether it's simply a case of some types of exercise regulating appetite better? Certainly for me, sprints and HARD distance running reduces my appetite. I burn more calories and eat less. Easy cardio makes me hungry and I eat more - perhaps more than I burn! But the problem with that theory is that hard strength training does make me very hungry immediately after. I couldn't say what effect it has on me over the long term though. Maybe I do eat less overall when I strength train?

I did find research to support the appetite regulation theory. For example, whilst running increases levels of ghrelin which should make you hungry they found that people who ran regularly learned to not overeat - without realizing it. Sub conscious self regulation of eating improved. They think because the hormones that tell your brain that you're full are also elevated. Running wasn't the only exercise that produced this effect, but it worked best. Cycling worked quite well - swimming not so good. But no real clue as to what volume and intensity worked best. And i'm thinking that could be the key?

I don't count calories - my body does a good job of self-regulating (from quite-lean to more-lean depending upon how I train). Do any of you that do calorie count notice a difference in appetite/calorie consumption according to the type of training you do? Do you cheat more on some training regimes? I'm pretty sure this is what's happening with me - appetite regulation is what's really making all the difference.


#4

You should do an N=1 experiment where you stop lifting, and do some slow steady state cardio for a while and see if it gives you the body you desire.


#5

^^ Good God, this sounds like hell


#6

Is it possible that the inefficiency of anaerobic energy production makes a difference? One glucose molecule yields 8 times as many units of ATP through oxidation/slow twitch vs. glycolysis/fast twitch. I've always assumed that my feeble, uneducated mind was missing the bigger bio-chemical picture, but that seems like a relevant piece of information to me. When they measure the calories burned during an exercise, do they account for how much glucose was used to make each unit of energy?


#7

I think that could well be the case. I'm pretty sure the studies measure in terms of calorie burn measured through oxygen consumption. I'll see if I can find out later today. I don't have full access to the online research papers though - I have to go by summaries and other peoples interpretation of the research.

I posted up two questions this one about the role of muscle mass in fat loss and another about the role of high intensity training. They're obviously too similar in peoples minds as the responses are all getting mixed up!! LOL

On the other thread someone made the point that it takes 7,000 calories to build 1lb of muscle.

I'm thinking a realistic goal for a woman is to gain 1lb of muscle in 2 months. That means that she could in theory eat an extra 7000 calories during that period without gaining fat. However, when the muscle gains stop (women typically aren't going to keep growing muscle at that rate indefinitely) then she has to learn to eat 3500 calories a month less just to maintain weight. If she wants to start losing excess fat she'll need to eat 7000 calories a month less than she's become accustomed to in order to loose 1lb of fat per month.

I think perhaps this is where things go wrong. There's a belief that just having that muscle lets you burn more calories, but in actual fact I think the moment you stop building muscle the calorie requirement plummets. Muscle doesn't significantly increase calorie burn/metabolism unless you're a massive, hugely developed bodybuilder.


#8

Apparently this makes no difference cmays007. Calories burned is calculated according to oxygen consumption and it seems that's all you need to know. Rather than try to paraphrase it all here I'll take chance that the admins don't mind and post a link. It's not from a competitor site - it's an educational establishment. I think a lot of people will be interested in the info:

http://www.unm.edu/~lkravitz/Article%20folder/caloricexp.html