Obesity Is a Disorder, Not a Character Flaw

 Obesity, technically speaking, is a disorder of excess fat accumulation.  How your body stores and accumulates fat is reasonably well-understood.  How is it, then, that there's so much confusion about what makes you fat?

First, the basics.  You eat a meal containing carbohydrates, such as bread, pasta, corn, potatoes, etc.  Your digestive system breaks down these carbohydrate molecules into glucose.  Your pancreas senses the glucose in the bloodstream and releases insulin in response.  In your muscle cells, this insulin binds to receptors that (indirectly) allow the glucose to pass through the cell membrane to be metabolized for energy.  In other words, glucose in the blood is required for insulin, and insulin is required to make use of the glucose.

One of the many effects of insulin is to signal your adipose tissue (your fat cells) to store fat, in the form of triglycerides.  There are many other hormones that signal these cells to release or mobilize the stored fat for energy, but these do not work in the presence of insulin.  It should already be clear that insulin levels are largely responsible for fat storage.  Another important fact is what triglycerides are made of, and how they are assembled.  First, the triglycerides in your fat cells are put together inside those cells.  Individual fat molecules (fatty acids) are able to penetrate the cell membrane, and they pass back and forth more or less freely.  Given the insulin signal, your adipose cells will assemble a triglyceride out of three (the "tri" part) fatty acids and one glycerol (the "glyceride" part) molecule.  This new, much larger molecule cannot penetrate the cell membrane, so it is trapped or stored in the fat tissue until the cell receives a signal to disassemble the molecule to release the individual fatty acid and glycerol molecules into the bloodstream.

If we're fighting obesity, that last bit is obviously what we want.  Once released, the fatty acids can be used directly for fuel by your cells (but again, not in the presence of insulin!) and the glycerol can be converted to glucose in the liver.  Note, too, that glycerol is created during glucose metabolism.  This is important because triglycerides cannot be manufactured without glucose.  So, without carbohydrates in your diet, it is doubly impossible to store fat, since both glucose and insulin are required for fat storage, and with no carbohydrates in your diet, none (or almost none) of either will be available.

This is where the "thermodynamic" theory of fat storage comes from.  In this cycle, any glucose not used by your muscle cells, or to a lesser degree your other cells, will be used to store fat, with the help of the insulin that was released in response to the meal.  "Calories in = calories out" makes intuitive sense, after all, but it is not the whole truth.  In fact, it's out the window entirely when you remove carbohydrates from the equation, because there's an entirely different metabolic process at work.

If you're on a low-carb diet, there is very little glucose in your blood stream.  There is some, because your liver will manufacture it for the few cells, mostly neurons, that still require it, but the levels are negligible.  The same is therefore true of insulin, which will be released in trace amounts by your pancreas, but the levels are nothing like those seen on a typical, government-recommended, diet.  So there is not nearly enough of either to meet your body's metabolic needs.  This is where the dietary fat comes in.  If your diet is very low in carbs, it must be very high in fat, or you're starving.  Starving is not good.  And - commit this to memory - fat is not bad.  That is the most important message of this blog, so I'm not going to leave it at that.

Basics again.  You eat a fatty meal, very low in carbohydrates.  A ribeye steak, let's say.  Soon, it's all in your small intestine, which tries to absorb nutrients from it through the intestinal walls.  Only water-soluble nutrients can penetrate these walls, though, so your gall bladder releases bile, produced by your liver, into the small intestine to allow absorption though a rather complex chemical process.  The result of this is availability of fat in the bloodstream, for use as cellular fuel.  Now, insulin signals muscle cells to use glucose exclusively as fuel, in part to manage your bloodsugar levels.  But since there's almost no insulin in your blood at this point, it's free to use fat instead.

This has certain benefits.  The most relevant here is that without insulin and glucose in the blood, this fat cannot be stored.  Any fat that you don't metabolize will be excreted instead, in your breath, sweat and urine.  This is where the thermodynamic theory of metabolism breaks down, because you simply get rid of what you don't use.  Eventually, you will have used or excreted all the fat in your bloodstream, unless you eat another fatty meal.  This situation stimulates your fat cells to release stored fat into the bloodstream for use as fuel.  If this happens on a large scale, of course, you lose weight, and this mode of metabolism is called ketosis.

This is a basic overview of the theory behind low-carb weight loss.  Nothing I've said here about how it works is terribly controversial.  The processes are pretty well understood, though there are still pockets of dissent in the medical community.  Ketosis is often referred to as an undesirable state.  I think this is mostly due to confusion with ketoacidosis, a dangerous condition suffered mostly by diabetics and alcoholics.  Others consider ketosis to be the body's emergency condition in response to starvation, which is correct, but most low-carbers consider it to be the body's preferred state.  I plan to defend this position in later posts.

The main source of controversy surrounding low-carb weight loss solutions is the prevalent idea that dietary fat is harmful, even if the diet is an effective weight loss solution.  Since this post is about obesity, I won't be addressing those concerns here, but rest assured they'll be well covered later.

So on one hand we have the popular weight loss dogma, which is all about calories and the insistence that obesity is caused by sin: gluttony and sloth.  To combat it, they say, we must reject what our bodies tell us and abstain from eating, and simultaneously exercise for its own sake to balance out the thermodynamic equation. 

 On the other, we have the low-carb theory, which tells us that we're not eating too much, we are very simply eating the wrong stuff.  According to this theory, it's ridiculous to cast a judgmental eye on obesity, especially considering our constant bombardment with bad information.  It's also a simple problem to solve, by eating delicious food in whatever quantities will satisfy your hunger.