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“What is Body Fat? Part II”
List of posts in Articles by Lyle McDonald
OK guys, here’s part two of Lyle’s chapter on body fat ….
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“What is Body Fat? Part II”
by Lyle McDonald, author The Rapid Fat Loss Handbook
www.bodyrecomposition.com
Dismissing a myth: fat cells aren’t all bad
If you asked most people about bodyfat, they’d say it was bad, they want to get rid of it, etc. Even researchers tend to promote this view, that bodyfat is a negative. The main focus tends to be on the negative health consequences of excess bodyfat (i.e. obesity).
But this is a simplistic and incorrect view. The existence of bodyfat has important roles in human health and survival beyond just energy storage (and beyond what I’m going to talk about next) although that is one of its primary roles. Basically, while too much bodyfat is definitely a health risk, too little can be just as problematic. I mentioned this in a previous chapter but want to go into more details here.
One of the roles of bodyfat is as a physical cushion for your internal organs. The physical nature of bodyfat allows it to dissipate force more effectively than muscle. Athletes involved in combative sports (football, etc) may benefit from carrying a little extra bodyfat, to protect their internals when someone rams into them. Of course, in modern society, most people don’t really have to worry about such things in the first place. Fat cells also act as insulation, keeping folks warm when it gets cold. Of course, most modern people can put on more clothes or turn up the heat, something that our ancestors couldn’t do.
A less well-regocnized aspect of fat cells are their critical role in immune and inflammatory responses. Pre-adipocytes, which I mentioned above, act like macrophages, cells which are critical for a proper immune system response. Of course, this certainly doesn’t provide an excuse or reason for carrying excess bodyfat. But people who diet to extremely lean levels frequently report getting sick more, feeling more inflammation. While this certainly can’t be completely attributed to the loss of bodyfat, that may be part of the puzzle.
As the final important role of bodyfat for this section (I’ll talk about the last couple next), I want to talk about the role of bodyfat stores in glucose tolerance. For optimal health, the body needs to maintain blood glucose between fairly narrow limits. Anyone familiar with diabetes (either Type I or Type II) knows that a big part of the health consequences of those diseases has to do with the chronic high blood glucose (hyperglycemia) that occurs. For reference, normal blood glucose is 80-120 ng/dl or so. Type I diabetics can run blood glucose in the 300-400′s or higher, Type II diabetics in the high 180′s or worse. Simply put, running chronically high blood glucose causes a lot of damage to the body.
Bodyfat is one of the places, along with muscle and liver, that your body stores glucose. Studies of rats, or humans, who have no bodyfat show chronic high blood glucose, just like diabetics. This is because muscle tissue has a limit to how much glucose it can store as glycogen. Diabetics can’t get blood glucose into the cells because they are insulin deficieint (Type I) or insulin resistant (Type II) ; rats and humans without any bodyfat don’t have any fat to store the glucose in. So the mechanism is different but the end result is the same. Of course, having no bodyfat (termed lipodystrophy) is rare and generally causes death at a very early age. So, if you’re reading this book, you don’t have it. My point is simply that all of the functions of bodyfat aren’t inherently negative. Fat exists for a reason, even if most of us are carrying more of it than we need or want.
But wait, there’s even more
Hopefully you get the idea that your bodyfat is an amazingly efficient place to store energy, in addition to having other roles mentioned above. Not only does it store incredible amounts of energy as it is, it can increase its energy storage if needed by making new fat cells. It’d be great, and I could end this chapter, if that’s all there was to it. As usual, it’s not and things are much more complicated.
In the last 5 to 10 years, the image of the fat cell as nothing more than a passive player in the body has gone the way of the dodo. On top of its major role in energy storage, your fat cells do so much more in terms modulating your overall metabolism. Body fat is turning out to be an endocrine organ in its own right.
On top of its obvious role in disposing of dietary fat, fat cells have been shown to play roles in overall glucose metabolism, blood pressure, appetite, fuel utilization, and hormone production to name just a few. And with each week, it seems as if yet another role for the humble fat cell in modulating human metabolism is found. We’ll talk about some, but not all, of these roles throughout this book, since fat cell metabolism is ultimately at the heart of body recomposition.
On top of storing and releasing triglycerides, your fat cells also produce hormones themselves. A partial list of the compounds released from your fat cells would include leptin, which is involved in appetite, hormone levels, fat burning and muscle loss, not to mention dozens of other systems ; angiotensin II, which is involved in blood pressure regulation and even controls blood flow to the fat cell itself ; Tumor necrosis factor-alpha, which has many varied functions including fat burning, immune functioning, and cell death ; IGF-1, which is an anabolic hormone ; inflammatory cytokines like Interleukin-6, which is involved in immune function among other things ; various prostaglandins, nitric oxide, acylation stimulation protein, resistin, adiponectin and I could probably list a half dozen more if I wanted to. New compounds are being found all the time. In the time since I first wrote this chapter, they’ve discovered fasting-induced adipose factor (FAIF) and a couple of others. By the time this book is actually published, there will probably be several more.
Fat cells are also one of the major sites of hormone metabolism. Testosterone is converted to estrogen (via the enzyme aromatase) in fat cells in both men and women. In fact, most of the estrogen in males (and in post-menopausal women) comes from the conversion of testosterone in fat cells. Carrying more bodyfat for males means not only more estrogen, but also less testosterone (yet another reason for athletes to avoid getting too fat). Athletes who use anabolic steroids (or even prohormones) without using an anti-aromatase will get more conversion to estrogen if they are carrying more bodyfat. The metabolism of other hormones such as DHEA and androstenedione also occurs in fat cells.
And that’s just a quick look at some of the things that your fat cells are doing in you body. With each week, researchers seem to turn up more. As a quick tangent, the discovery that fat cells were more than a passive place to store energy has revolutionized the study of obesity. So instead of dozens of studies indicating why fiber is important for weight loss, there are now hundreds/thousands of studies dealing with all of the myriad hormones that are released from fat cells, and how they affect metabolism.
Although many of these factors can’t be controlled at this point, their discovery has opened up an entirely new area of possibilities for body recompositionists. At the very least, we know more about why our bodies are reacting a certain way. Knowing the why gives us at least some possibility of knowing how to do something about it.
We can modulate levels of some of these molecules, to modify body composition. Leptin is arguably one of the more important although others are turning out to play equally crucial roles. Others can’t be controlled right now so I won’t spend much time on them.
The main point for you to get from this chapter being that fat cells are far more than just a passive storage site for excess energy. Yes, they are amazingly well adapted to their role in energy storage but they do far more. They are one also one of the primary keys in modulating your overall metabolism, which is obviously a key in manipulating body composition.
