Simplified Science: How We Get Fat
People often avoid the word "fat" in our society. Maybe that's because 1 out of every 3 adults in America is obese. Somehow, over time, the dreaded word became too insensitive sounding so instead we choose to say overweight, heavy or chunky. However, let's not forget what we are talking about when we say we want to lose weight. What we really mean is we want to get rid of some of the fat we have stored in our fat cells, so they (and our waistlines) will become smaller. Our whole lives we have been bombarded with health and nutrition advice about how to lose weight, whether we wanted to hear it or not. But, if you really want to know how to shed fat from your body, shouldn't you first know how the fat got there in the first place?
If you learn one thing today, let it be this: fat doesn't get stored as fat, sugar gets stored as fat.
I will try to keep things as simple as possible, but unfortunately I am warning you that you are about to get hit with a bit of science.
Here we go:
Every single form of carbohydrate you eat gets broken down by the body into sugar molecules called glucose, which travel around your body in the blood. Hence the term "blood sugar," which you have probably heard before. When I say every carb, I mean it. This means every candy bar, apple, sweet potato and slice of bread gets converted to sugar.
Photo courtesy of ashleyharperevans.com
Now let's talk about our frenemy named insulin. Insulin is a hormone that is secreted anytime sugar enters the bloodstream in order to tell the sugar where to go. While some sugar is immediately taken from the blood and used for energy, insulin tells other sugar to be stored for later in your liver and muscles, in a form called glycogen. Glycogen is the energy your body looks to when you're working hard at the gym and your cells need more fuel. However, when your liver and muscle cells are full (which they very often are), the rest of the sugar in your bloodstream is converted to fat. Like I said before: fat doesn't get stored as fat, sugar gets stored as fat.
Still with me? Let's continue with how fat actually gets stored.
Fat exists in two very different forms that serve very different purposes. First, there are the good guys: fatty acids, the form your excess sugar gets converted to. These little guys are small enough to slip through the cell membranes surrounding every fat cell in your body. Thus, they can freely flow in and out of the cell to be burned as fuel whenever needed. Next, we have the bad guys: triglycerides. Sound familiar from your high school bio class? This form of fat is composed of three fatty acids that are bound together by another molecule called a glycerol. Triglycerides are built inside your fat cells and are too big to get out. Imagine buying an ikea table, putting it together in the store and then realizing it's too big to squeeze out the door. When triglycerides are constructed and get stuck inside the cell (as they always are), your fat cells grow larger and you get fatter. The reason insulin is important is because it's the signal that tells your fatty acids to flow into your fat cells in the first place.
A close-up of fat cells from a scanning electron microscope. Photo courtesy of huffingtonpost.com
Let's recap exactly how you get fat.
1. Carbs get broken down into sugar.
2. Excess sugar get converted to fatty acids.
3. Insulin promotes the flow of fatty acids into the fat cells, where they are bundled into triglycerides.
4. Fat is stored.
5. You get fatter.
There you have it people. So what is the takeaway from all this science-y gibberish? Cut out the sugar (i.e. carbs) and you'll stop storing fat.
If you're more of a visual learner, or just want to understand a little more about insulin, take a look at this awesome 3 minute video.
Also, check out Gary Taube's book, "Why We Get Fat and What to Do About It," where a lot of this information came from.
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