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“What is Body Fat? Part I”
List of posts in Articles by Lyle McDonald
One thing that I’ve noticed since I’ve been on my fat loss journey is not only do we demonize dietary fat, but we also do the same to the fat that’s literally attached to our asses! I can remember thinking that I wished that I could take a knife and just cut all the fat from my belly in one full swipe. Can any of you guys relate to this feeling? I thought so; however, why do we think this way? If you ask us about muscles, then we’re ready to tell you about the different types of muscle fibers, fast or slow, red or white, etc., but when it comes to body fat, we could care less about the different types as long as we can get rid of them.
Well, this week, we are going to solve that problem. No longer are we going to look at fat as our bulky, squishy enemy. With the help of our good friend Lyle McDonald, we are going to learn more about body fat than you probably knew existed. But that’s cool because, as I always say, if you want to lose and keep the fat off, then you must “Feed Your Brain to Lose the Fat!“. Enjoy Lyle’s two part post and please feel free to leave a comment.
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What is Body Fat? Part I
By Lyle McDonald, author of Rapid Fat Loss Handbook
www.bodyrecomposition.com
What is it?
The more technical term for bodyfat is adipose tissue, with individual cells being called adipocytes (adipo = fat ; cyte = cell). In humans, the primary type of fat cell is called white adipose tissue, or WAT, so named because of its color (it’s actually sort of a milky yellow). While there is another type of fat, called brown adipose tissue or BAT (which is actually reddish/orangeish), it isn’t found to a great degree in adult humans. We’ll come back to BAT in the next chapter.
In humans, there may be anywhere from XXX to YYY billion fat cells, which range in diameter from 70 to 120 µm. WAT in humans is composed primarily (anywhere from 80 to 95%) of lipid. By lipid, I mean stored triglycerides (TG) which is simply a glycerol molecule bound to three free fatty acid (FFA) chains.
The remaining part of the fat cell is comprised of a little bit of water as well as all of the cellular machinery needed to produce the various enzymes, proteins, and products that fat cells need to do their duty. As it’s turning out, fat cells produce quite a bit of stuff, some good, some bad, that affects your overall metabolism.
For the record, one pound of fat is 454 grams and let’s assume 90% lipid on average. So about 400 or so grams is actual stored TG. When burned by the body, one gram of fat provides 9 calories so 400 grams of fat contains about 3600 calories of stored energy. Now you know where the old axiom of ~3,500 calories to lose a pound of fat comes from.
What’s it for?
Other than being considered unattractive in modern society, you may be wondering what role fat cells play in the body. The main role is as an energy storage dump. In fact, up until about 10 years ago, the predominant view of fat cells is that is all they were: a passive place for the body to store energy for times when there wasn’t enough food available. This turns out to be drastically incorrect but, before we go on, let’s look at that one aspect of fat cells.
In terms of energy storage, fat cells are truly exceptional in their capacity to do so. As mentioned above, a single pound of fat contains roughly 3,500 calories of stored energy. Assuming you could burn 100% fat as fuel (you can’t for reasons that aren’t important now), this is enough energy for a 150 pound person to walk roughly 35 miles or so before using it all up. That’s ONE pound of fat. Even at an extremely low 5 lbs of bodyfat, which is near the extreme extreme low-end, you’re looking at ~15,000 calories of stored energy. That’s 150 miles of straight walking, or so.
Here are some more numbers to give you a little better perspective. The average American male who may weigh 160 lbs with 15% bodyfat has 24 pounds of bodyfat which is about 84,000 calories of stored energy or so. He’ll have a metabolic rate close to 3,000 calories/day. Even with complete starvation, that’d get him through nearly 30 days without any food, assuming he was using 100% fat. Extremely obese individuals may have upwards of 50-100 lbs of stored fat to the tune of 175,000-350,000 calories of stored energy. That’ll keep them alive for several months at least without emptying their fat stores. Some very obese individuals have been starved for up to a year without problems.
In contrast, your other major energy source, which is stored carbohydrate in your muscles and liver, only amounts to about 500 grams at the maximum. Each of those grams of carbs gives your body 4 calories so that’s 2000 calories or so as stored glycogen. Not even enough to meet a single’s days caloric requirements. So at the low end, fat has a good 7 times as much energy as all of the carbohydrate in your body. At the high end, it can be several hundred times more. Although you don’t really want to use body protein for energy, assuming you used it all, it’d still only provide about 10,000 calories, still far fewer than your bodyfat. And you’d die long before you could use it all up anyhow.
The reason for the difference, if you must know, is water. Carbohydrate (stored in your muscles and liver as glycogen) is accompanied by a good bit of water. For every gram of glycogen stored, you store anywhere from 3-4 grams of water with it. In contrast, triglycerides only require about 1 gram of water for every gram of fat stored.
To store even 10,000 calories of energy as carbohydrate (2,500 grams of carbohydrate) would require 7,500-10,000 grams of water. And you’d (well, your cells anyhow) explode. Since it doesn’t have a lot of water associated with it, fat is a very space efficient way to store energy. Well, relatively speaking anyhow.
On top of that, a gram of fat provides more useable energy than either a gram of carbohdyrate or protein. As above, the commonly given values are 9 calories/gram for fat and only 4 calories/gram for carbohydrates and proteins. So on top of being able to store more grams of fat total, each of those grams provides more useable energy to the body. Yes, truly an ideal storage form of energy.
Obviously, from an evolutionary standpoint, the exceptional energy storage capacity of fat cells were an excellent advantage. Being able to store an effectively unlimited amount of energy in a relatively limited amount of space made it easier to survive through this time period when food wasn’t available. Now it’s just another evolutionary leftover that makes it a bitch to get into shape.
But wait, there’s more
There’s an old (and incorrect idea) that adult humans don’t make new fat cells. That is, and we’ll discuss this more in a bit, you get born with a certain number of fat cells and you may develop more at puberty or during pregnancy but that’s it ; your body doesn’t make new fat cells. Everything in that sentence is true except the last statement ; even non-pregnant adults can make new fat cells.
Usually this happens when the fat cells you have reach a certain size ; that is, they are as full as they can physically be. When this occurs, the actual stretching of the fat cell stimulates the release of factors, such as Angiotensin II, prostacylin and others, which ‘tell’ the body to make new fat cells from something called preadipocytes. Preadipocytes are dormant cells, sort of soldiers who wait for the signals to get called into action. When the right growth factors are released, preadipocytes mature into normal adipocytes. Voila! New fat cells.
Those newly formed fat cells can now be filled with yet more fat and glucose. In fact, a new class of diabetic drugs (called TZD drugs) appear to work by stimulating the production of new fat cells, which gives the blood glucose and fatty acids another place to go. Oh yeah, if the new fat cells get too large, your body will keep making more.
Unfortunately, getting rid of fat cells is nearly (but not completely) impossible. Sure, liposuction is always available but, beyond that, eliminating fat cells is very difficult and only occurs under extremely severe conditions. I’ll talk about fat cell apoptosis (death) later on.
If there is a single reason for athletes not to get fat in the first place, this is probably it: if your fat cells get too big, your body will make new ones. And it’s nearly impossible to get rid of the new ones . Obviously, if you’re already very fat, there’s little you can do: you’re pretty much stuck with your fat cells short of liposuction or something along those lines. But if you’re a lean athlete looking to gain weight (and realizing that you must gain some bodyfat to do it effectively), you should keep a lid on that fat gain. You don’t want to stimulate your body to make new fat cells.
(to be continued …)
October 7th, 2008 at 5:13 pm
A couple of thoughts, I used to tell my sons when they were little how great it was to be fat! We were at the beach and they notice how long I could stay in the cold water. I told then walruses were very happy! I could also float better then most of the skinny folk out there.
My second thought was to tell my sons that if I was a bear – I would be set! I could fatten myself up during the summer and sleep during the winter. Unfortunately I ended up eating during the winter too!
This is a good post on fat – I used to think this was most of the picture but I’ve come to realize that this is yet another piece of the puzzle.
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Muata Reply:
October 8th, 2008 at 11:40 am
@John W. Zimmer – John those are great anecdotes! I use to like the idea of being the “Big Guy” (in size not muscle) in the room. I honestly believed that I was “genetically” wired to be big, so why worry about not being able to see my … feet … when I looked down;) Yes, there’s a lot more to body fat than we’ve been taught, and I’m just glad that I know one of the “nerds” in the industry to give us the ins and outs. Thanks for leaving a comment John …
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October 8th, 2008 at 1:53 am
An amazing breakdown of the F word. Excellent. I thoroughly enjoyed the post.
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Muata Reply:
October 8th, 2008 at 11:32 am
@Usman – Hey, I’m glad that you enjoyed Lyle’s post. The second part is just as informative; you’ll see. Also, I haven’t read any other author break down body fat the way that Lyle does, and I wanted to share it with folks who might never come across his work(s). Thanks for leaving a comment Usman …
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October 8th, 2008 at 5:56 pm
Great article on fat.Yes, Lyle is a major nerd. He even admits to this.That nerd knows his stuff when it comes to
changing your body. Folks, I highly recommend checking his site out.His books are a MUST read IMO.
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Muata Reply:
October 10th, 2008 at 8:25 am
@Robert – Robert, you’re absolutely right! Lyle knows his stuff, and I’m glad that I’m not the only one who knows.
Thanks for your comment …..
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