Whether you are trying to climb Mount Everest, run a marathon or lose 15lbs, your main goal should be to teach your body to burn fat. The human body can only utilize fat or carbohydrate for energy. Like a car that runs on premium versus regular, the fuel you put in your body ultimately affects the efficiency and output of your body. Contrary to previous beliefs, the preferred fuel for your body is fat and not carbohydrate.
Why is fat preferred over carbohydrate?
Unless you are running quickly away from a lion, any long, sustained energetic effort requires fat as fuel. Ideally, your body utilizes sugar mostly only in times of stress and for higher intensity bouts of exercise. As far as storage sites go, carbohydrates (stored as glycogen,) are stored in liver and muscle—but only in limited amounts. These storage sites are indicative of their metabolic purpose. When blood sugar is running low, the liver will break down its glycogen to maintain a stable glucose supply to the brain. When quick energy is needed, muscles call on glycogen for the extra demand. The average person can only store about 1300-2000 calories of glycogen. As glycogen becomes depleted, fatigue sets in and you head to the vending machine trying to replenish your diminished supplies.
On the contrary, the average person has about 80,000 calories of fat stored on their bodies. In sheer availability alone, using a more abundant fuel source is preferred—especially considering fat burning does not result in overwhelming fatigue. In addition, the quick-burning carbohydrate fuel used by muscle during high intensity burns at a price—the price being biological waste products such as lactic acid. Thankfully the burning of fat does not render these waste products. Rather, under healthy conditions, a person can easily access stored fat for energy. Because most activity of our daily lives is aerobic (low intensity, with plenty of oxygen), fat meets most energy demands as long as we are fat-adapted and can access it efficiently.
Why have we shifted as a culture towards a carbohydrate metabolism when fat is preferred?
With the great abundance of sugar and carbohydrates in the average American diet, it is no wonder that we have trained our bodies to burn and rely on sugar. Although biologically our bodies favor a fat metabolism, through our environment we have trained our bodies to favour and crave carbohydrates. Because of the little storage we have for glycogen, we constantly crave more and more carbohydrate. While they give us a quick boost of energy, any excess carbohydrate taken in becomes stored as fat—fat that we cannot burn off efficiently because our bodies favor the carbohydrate.
How do you know if you’re using fat?
If you suspect you may be a carbohydrate-burner instead of a fat burner, here are some ways you might be able to tell:
1. You feel starved and cranky after not eating for a few hours
2. You are unable to produce sustained bursts of energy during exercise
3. You need food after exercising a short period of time at any intensity
4. You have accumulated body weight that you cannot seem to get rid of
The easiest and most reliable way to find your metabolic fuel source is through metabolic testing. Through a Resting Metabolic Rate Test (RMR) you can find out exactly how many calories your body burns at rest and what kind of calories they are. So, if you have been struggling with weight loss and cannot kick your sugar habit, the scientific way to hone in is to find your actual numbers. To find your fuel source during exercise, a VO2 Test will show you not only your fuel source at different intensities and heart rates, but also exactly how many calories you burn. These tools hand in hand will give you a snapshot of your actual personal physiology.
How can you best burn body fat?
Once you have determined your fuel source, you must ask your body to rely on fat. Do this by limiting excess sugar and carbohydrate. The body will preferentially burn what it’s accustomed to burning; so by limiting the carbohydrate, your body will revert back to fat metabolism. In addition, stay away from higher intensity exercises, at least in the first stages. By staying in fully aerobic exercise, your body will train itself to use fat as fuel and create an “aerobic base.” Once developing your aerobic base and you bring back the high intensity exercise, you will actually still be able to burn a higher percentage of fat.