Fats, Carbs, and Your Body

There’s never too much of a good thing, except when it comes to your body. Think of your body as a machine: we intake food (energy), metabolize it to break it down to useful parts, then burn it off or store it. If we intake more energy than we expend, our body stores the rest.

We store extra fat and carbs as a survival mechanism our ancestors utilized tens of thousands of years ago, back when food was scarce. Now, our body still does that, even when we don’t need to hoard excess energy.

But how does our body use this stored energy? It can’t just sit there forever, right? Well, it depends. Not only does it depend on how often you exercise, but how you choose to exercise. Based on your body’s needs, it will utilize different sources of energy, automatically!

Let’s look at runners. If you’re a runner, chances are you eat a lot after a long run. Well, that’s necessary to replenish all the energy you’ve expended during that training session. Sustained exercise over a period of several minutes to hours is defined as an aerobic activity. Meaning, this type of exercise uses lots of oxygen to keep you going. Your body uses oxygen to break down fats quickly, so you don’t fall flat on your face.

But you might do that on your own anyway…

Basically, for exercise that lasts a long time, your body tends to use fats more, as the oxygen you breathe makes it easier to break down fats efficiently. (Remember the Krebs cycle from high school biology? That’s what I’m talking about here.)

You will still use free glucose in your muscles and blood, while stored glycogen (aka stored glucose) will also be used. Which brings us to the next type of exercising.

There’s another type of workout called anaerobic activity. If aerobic requires oxygen, then guess what, anaerobic doesn’t! This type of exercise is typically very fast-paced, doesn’t last long, and can get your heart rate up very fast. (Think HIIT, weightlifting, and sprinting.) However, we all have stored glycogen in our livers that is also easy to break down and use quickly.

Since you are burning through energy at a very quick rate, your body needs to break down stored energy incredibly fast to keep up. That’s where carbs come in. These little bundles of energy can be broken down almost instantaneously, keeping you going at 100% for short bursts of activity. Now there’s two main systems that can break down carbs, because we don’t want this to be TOO easy. Below, I’m going to list both the carb metabolism cycles as well as the fat metabolism I mentioned above.

So what does this all mean? Well, for one it can give you a good gauge on what fuel sources to consume before a workout. While this obviously doesn’t cover EVERYONE, it can help you understand why the foods you eat do actually matter. If you’re a runner, you’ll usually want something a bit fatty prior to your longer runs. Likewise, short distance track athletes and weightlifters usually tend to go more carb-heavy to keep them from fatiguing too quickly.

This is also why so many distance athletes carbo-load before a big race. By eating a lot of carbs (pastas, breads, potatoes, etc), your body will store the excess glucose as glycogen, which builds up your reservoir of available glucose during the race.

Carbo-loading isn’t something to do everyday though (but I love my donuts!)

So what do you think? Will this help you work out more effectively? Let me know what you think in the comments below, and sign up for my email list today to get even more specifics on how your body metabolizes energy!