We talked recently about heart monitors and how they’re helpful in determining how well you’re doing with your fitness routine. You’re often taught to exercise in the “fat burning zone” to maximize the utilization of fat.
We want to burn calories and fat. That fat burning zone is where you burn the highest percentage of fat as your energy source during your exercise. It’s usually at about 60-70% of your maximum heart rate. We talked last time about maximum heart rate (220-your age). That’s a good estimate. We’re then taking 60-70% of that maximum heart rate. It’s somewhere between 108-126 if you’re 40 years old. In theory, that’s your fat burning zone. That means that the highest percentage of calories burned is actually coming from fat.
The problem is that you’re not actually burning very many calories. Most of the calories you’re burning are coming from fat, but the issue is that you’re not burning that many calories. What you really want to do is bump up the intensity. If you bump up the intensity, you’re burning a lot more calories. As you’re burning a lot more calories, your body can’t use fat quite as efficiently and so you’re burning more calories from carbohydrate. Is there something wrong with that? Absolutely not! If you’re burning more calories from carbohydrate, what you’re doing is decreasing your carbohydrate stores.
We can store carbohydrate in our muscles. If we start decreasing the carbohydrate stores, you can actually replace that carbohydrate. For example, you can’t put more gasoline into your car’s gas tank until your burn the gas off. There’s only so much carbohydrate that will fit into your muscles. If you don’t actually decrease the amount that’s in the muscle, then you can’t replace it. You want to burn off that carbohydrate that’s in the muscles. If you burn that off, then you can actually put more in. That’s how we can smooth over blood sugar swings. Then, you can get a little leeway on your carbohydrates.
There are two reasons why the fat burning zone doesn’t work really well. The first is you’re not burning that many calories. If you bump up the intensity, you’re going to burn a lot more calories. Number two, you want to use some of the carbohydrates stores because you want to be able to replace those stores. When you’re exercising, use a heart rate monitor and bump up the heart rate to higher than the fat burning zone. If you’re just starting an exercise program, you can’t just jump right into that. But if you’ve been in exercise for a while you can go into that higher intensity as your fitness level increases. That’s where you burn the most calories and you get the most after burn as well. That’s burning calories long after you’ve finished exercising.
I have a great 20 minute High Intensity Interval Training (HIIT) workout you can use to get the intensity up! https://youtu.be/WBAw-pRraGY