Why does the body burn muscle during a deficit?

Discussion in 'Health and Fitness' started by Timmy Boy, Mar 23, 2015.

  1. Timmy Boy

    Timmy Boy Man on a Mission

    So I understand that, in order to lose weight, you need to create a caloric deficit.

    Whilst losing weight, it is inevitable that your body will burn some muscle along with the fat.

    But then the question is... why is that? Why does the body not just burn fat and leave the muscle alone?

    Most people just seem to accept this as a given. The only explanation I have found via a google search is that the body uses protein to fuel the burning of fat; therefore, during a deficit, it will look to obtain that protein from muscle fibres... but surely this is just a protein deficit that can be rectified by ensuring that you ingest enough protein during the cut? And if that's the case, isn't it thus possible to build muscle during a cut unless you have basically run out of fat reserves, as Scooby suggests?

    Is it simply the case that it's harder to consume the requisite level protein during a cut but theoretically possible?

    BTW I'm not saying the theory is wrong, I'm just saying I don't get it.
    Last edited: Mar 23, 2015
  2. Fish Of Doom

    Fish Of Doom Will : Mind : Motion Supporter

    protein fuelling the burning of fat? source? the burning of fat IS a fuel source.

    in general terms, if you're losing significant amounts of muscle, your calorie deficit is too big and you're not eating enough protein anyway.
  3. Timmy Boy

    Timmy Boy Man on a Mission

    Just something I found on google, not saying it's necessarily right. This is the link@ http://fitness.stackexchange.com/questions/1341/when-will-muscle-be-cannibalized

    Quote (emphasis mine):

    "In order for fat or carbs (or protein, as a last resort) to be fully converted into energy (i.e. burned), they have to go through a process called the citric acid cycle, which releases energy through a number of reactions. This is the predominant energy system at rest and during prolonged aerobic exercise, and the primary source of energy in these states is usually fat. But here's the thing: one of the intermediary products of the citric acid cycle (oxaloacetate) requires a derivative from either carbs or protein. Because of this, to metabolize fat, you have to break down at least some carbs or protein. A common summary of this is "fat burns in a flame of carbohydrates." Your body prefers to burn carbs over protein, but it has limited carb stores. If it runs out of those, it will start breaking down protein (into ketone bodies) to be used as fuel. This is also important for fueling your brain once you run out of carbs, since it can only use carbs or ketone bodies as fuel (not fat). It kind of makes sense that your body would evolve the ability to use protein for energy as a back-up energy source considering there's so much of it in your body."

    So this guy seems to be saying that your body will consume muscle protein during a cut to keep the fat burning process going, which would seem to imply that you can prevent this from happening by keeping your protein intake up despite the caloric deficit. I.e. in theory you could put on muscle during a cut provided you ate enough protein and had at least some fat reserves left - N.B. this is what Scooby suggests (see http://scoobysworkshop.com/bulking-and-cutting/), but most experts still seem to buy into bulking and cutting.

    But why should you lose *any* muscle during a cut provided you are eating enough protein? Why should the body cannibalise muscle tissue at all?
    Last edited: Mar 23, 2015
  4. Fish Of Doom

    Fish Of Doom Will : Mind : Motion Supporter

    because the body is a dumb turd, mainly. it doesn't understand context.
  5. Timmy Boy

    Timmy Boy Man on a Mission

    So when Scooby claims that the body is "smart" and it will only burn muscle for energy once your fat reserves are more or less depleted... he is incorrect?

    I knew he was in a minority on this issue, I just didn't get why.
  6. Fish Of Doom

    Fish Of Doom Will : Mind : Motion Supporter

    metabolism is ridiculously complicated. entire careers are built on studying it. fitness on the other hand has mostly been largely anecdotal for a long time, although some people such as brad schoenfeld and alan aragon are working to change that, and therewas a fair amount of scientific work on the subject done in the last century.

    and yes, as far as i am aware, he is incorrect, a sufficiently large deficit will eat up muscle like candy. thing is, you're not supposed to use large deficits in the first place, so under the type of cutting diet that he would use, being a bodybuilder, he would be mostly correct (from what i've seen, it's generally acknowledged that muscle loss does occur, but is minimal, under small caloric deficits), because he already knows how to cut, which most people don't. check out the work of alan aragon, brad schoenfeld, layne norton and mike israetel if you want the real deal in terms of scientific research into fitness nutrition (ie they actually perform and publish studies on it, particularly aragon and schoenfeld)
  7. narcsarge

    narcsarge Masticated Whey

    You guys are above my little pea brain. I've always understood that the body, being a lazy sod in its design, would rather burn the 4 calories for carbohydrate and protein synthesis (no idea about the scientific names) then the 9 calories for fat synthesis. I know there are training systems and exercises that will trick the body into using fat as a primary energy source and we only have to look at athletes within the sport to see the results. Not a lot of 250 pound marathon runners, or Tour de France competitors, or soccer players. Not a lot of thin, wispy blokes in strongmen competitons.
  8. rabid_wombat

    rabid_wombat Valued Member

    A well-balanced diet and fitness program will avoid any pitfalls here. There's a delicacy to the processes for which the body uses fats, proteins and carbohydrates. Calorie intake levels complicates this, so if you're not careful when operating at a deficit, and not getting enough of any combination of the three, it can have unintended effects. This can come in the form of muscle loss, the storage of more fat, etc. It pays to consult your doctor when taking on a dietary change for weight loss to ensure you're on target for the nutrients you require for good health, and achieve a safe rate of weight loss.
  9. FunnyBadger

    FunnyBadger I love food :)

    Muscle is expensive for the body to run so when operating a large calorie deficit the body decides it can't afford to support the muscle and the muscle atrophies. During a small calorie deficit with a highly nutritious high protein diet your body can maintain the majority of the muscle but as the deficit widens all the other factors involved in muscle growth/maintenance (not just dietary ones) need to improve accordingly and that's incredibly hard to do past a certain point.

    It's no different than if your financial expenses go up you have to cut back some parts of your lifestyle. The body has a finite ability to maintain tissue (limited income) in a callorie deficit (lower earnings/increased overheads) then atrophy will occur (cutbacks).

    I don't know the chemical processes that govern that phenominon but you don't really need to you just need to understand the basics of how it relates to you.
    Last edited: Mar 24, 2015
  10. Kframe

    Kframe Valued Member

    Im going to try and find a article i saw on Bodybuilding.com. It was as prolonged test done at a college on well trained athletes. They put them into 2 groups. One group had a large deficit of about 700 under maintenance and the other was about 450 under maintenance. The 700 group had a shorter time in study, the 450 group had a longer time in study. The goal was 4% reduction in body fat. They were instructed to do a food log as well as their normal athletic activity.

    They also had to do 3 days a week of a weight lifting routine with a coach that was logged and input.

    What they found out was that the fast group, didnt loose any muslce but did not gain any except for a small gain in the Squat. The slow group however actually gained muscle mass in all areas of measure(dexa) after it was said and done.

    I dont know if this helps but it seems to point to the idea that with a small deficit you can gain muscle mass. It seams that exercise has a lot to do with maintaining muscle.

    Still dosent explain why the body would metabolize muscle at all..
  11. Fish Of Doom

    Fish Of Doom Will : Mind : Motion Supporter

    short answer, partly because aminoacids are also part of energy metabolism (krebs cycle) and because the body reacts to the stimuli it's given but does not understand context, so if there's no stimuli that causes stress better handled by maintaining or building muscle, it generally won't maintain that muscle. long answer would require me to check my textbooks and i don't wanna :p
  12. Fish Of Doom

    Fish Of Doom Will : Mind : Motion Supporter

    key point to understand is that your body pretty much cares about nothing beyond keeping your brain working (and by extension, the various organs and systems that keep it working). anything further, it senses some sort of stress, it reacts to that stress, and if the stress keeps occurring, it adapts to that stress. if the stress goes away and doesn't come back , those adaptations are basically a stockpile of snacks for when calories aren't coming in from the outside.
  13. matveimediaarts

    matveimediaarts Underappreciated genius

    My biology prof made the krebs cycle sooooo boring. :p I still don't know it. :bang:

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