Turning Your Body Into a Fat-Burning Machine

If you feel like any extra calories you eat go straight to your belly or thighs, you're not imagining things. Those are usually the areas where you store fat because of your genes, hormones, age, lifestyle, and other factors. 

Your body tends to hoard calories as fat to keep you alive and safe. The challenge is learning how to get rid of that extra fat.

You hear a lot about fat-burning gimmicks such as working out in the fat-burning zone, spot reduction, and foods or supplements that supposedly burn more fat. Instead of seeking a quick fix that is not likely to work, learn how to burn fat through a variety of types of exercise.

 The Truth About Your Fat-Burning Zone for Weight Loss

Basics of Burning Fat

If you're trying to lose weight, knowing how your body uses calories for fuel can make a difference in how you approach your weight loss program. You get your energy from fat, carbohydrates, and protein. Which one your body draws from depends on the kind of activity you're doing.

Most people want to use fat for energy, which makes sense. You figure that the more fat you can use as fuel, the less fat you will have in your body. But, using more fat doesn't automatically lead to losing more fat. Understanding the best way to burn fat starts with some basic facts about how your body gets its energy.1

The body primarily uses fat and carbohydrates for fuel. A small amount of protein is used during exercise, but it's mainly used to repair the muscles after exercise. The ratio of these fuels will shift depending on the activity you're doing.

For higher-intensity exercises, such as fast-paced running, the body will rely more on carbs for fuel than fat. That's because the metabolic pathways available to break down carbs for energy are more efficient than the pathways available for fat breakdown. For long, slower exercise, fat is used more for energy than carbs.

When it comes to weight loss, it doesn't matter what type of fuel you use. What matters is how many calories you burn as opposed to how many calories you take in.

This is a very simplified look at energy with a solid take-home message. When it comes to weight loss, what matters is burning more calories, not necessarily using more fat for energy. The harder you work, the more calories you'll burn overall.

Think about it this way—when you sit or sleep, you're in your prime fat-burning mode. But, you've probably never contemplated the idea of sleeping more to lose weight, as lovely as that thought is. The bottom line is that just because you're using more fat as energy doesn't mean you're burning more calories.

Myth of the Fat Burning Zone

Exercising at lower intensities will use more fat for energy.2 This basic premise is what started the theory of the fat burning zone, which is the idea that working in a certain heart rate zone (around 55 to 65% of your maximum heart rate) will allow your body to burn more fat.

Over the years, this theory has become so ingrained in our exercise experience that we see it touted in books, charts, websites, magazines, and even on cardio machines at the gym. The trouble is that it's misleading.

Working at lower intensities isn't necessarily a bad thing, but it won't burn more fat off your body unless you're burning more calories than you're eating. One way to increase your calorie burn is to exercise at higher intensities.

This doesn't necessarily mean that you should avoid low-intensity exercise if you want to burn more fat. There are some specific things you can do to burn more fat and it all starts with how and how much you exercise.

Burn Fat With a Mix of Cardio

You may be confused about exactly how hard to work during cardio. You may even think that high-intensity exercise is the only way to go. After all, you can burn more calories and, even better, you don't have to spend as much time doing it.

But having some variety can help you stimulate all of your different energy systems, protect you from overuse injuries, and help you enjoy your workouts more. You can set up a cardio program that includes a variety of different workouts at different intensities.

High-Intensity Cardio

For our purposes here, high-intensity cardio falls between about 80 to 90% of your maximum heart rate (MHR) or, if you're not using heart rate zones, about a 6 to 8 on a 10-point perceived exertion scale. What this translates to is exercise at a level that feels challenging and leaves you too breathless to talk in complete sentences.

But you're not going all out, as in sprinting as fast as you can. There's no doubt that some high-intensity training work can be helpful for weight loss as well as improving endurance and aerobic capacity.

For example, a 150-pound person would burn about 341 calories after running at 6 mph for 30 minutes.3 If this person walked at 3.5 mph for that same length of time, they would burn 136 calories.

But, the number of calories you can burn isn't the whole story. Too many high-intensity workouts every week, can put you at risk in a number of ways.