Which Exercises Burn the Most Fat?
I'm wondering if burning fat and burning calories are the same thing. I'm also confused when I hear that some exercises, like walking and slow jogging, are better for "fat burning" and weight loss. Please explain.
When you exercise, your muscles, as well as other parts of the body including the brain, burn fuel to do their work. This fuel, which is measured in calories, is supplied by two primary sources in your body:
Stored carbohydrate called glycogen, which is made from many sugar units called glucose, and is found in the muscles and liver.
Stored body fat found in fat cells and also tucked away in small droplets in the muscles.
Take note that protein is not a major source of energy during exercise.
How many total calories you burn during your activity, as well as how much of this fuel comes from glycogen and how much comes from fat, depends primarily upon two factors: the intensity of the exercise (how hard you are working out) and your fitness level.
Both carbohydrate and fat are used as calorie sources during most activities, with a few exceptions. During light or low-effort exercise such as walking, fat is the primary fuel source, supplying about 60 to 70 percent of the calories burned. Carbohydrate or glucose burning makes up the difference. As you increase your effort — for example, speeding up your walking pace to a jog — your muscles burn more calories per minute, and a shift begins towards carbohydrate supplying more of the energy, while fat supplies less.
The type of fuel you burn moves on a gradual continuum from fat to carbohydrate as you increase exercise intensity. That means you proportionally burn more carbohydrate and less fat as you progress from a jog, to a run, to an even faster run. The contribution of fat to the fuel mix drops off as you increase your effort, and carbohydrate burning increases. At very high intensity, such as a quick running pace that you wouldn't be able to maintain for much more than a few minutes, carbohydrate is the only fuel source.
What all this energy burning boils down to is this: Fat is a good source of fuel at low-intensity exercises when your breathing rate and oxygen use can keep up with the demands of the exercise. This type of exercise is often referred to as "aerobic" meaning "with oxygen." Carbohydrate, on the other hand, is better suited as a fuel source during high-intensity efforts, such as fast running when breathing rate or oxygen needs fall short of the energy demands of the exercise. This type of high-intensity exercise is called "anaerobic," or without oxygen.
Here's where your fitness level plays a big part in how much fat and carbohydrate you burn. Part of the adaptation to training, such as starting a running program, is that your muscles become better fat burners. This mean that at a given running pace, you burn more fat and less carbohydrate than you burned when you were less fit but running the same pace. When you increase your fat-burning ability, you also increase your ability to exercise comfortably for a longer period of time — therefore burning more calories. This happens because your muscles and liver can only store a limited amount of glycogen — enough to fuel about 90 minutes to just over two hours of continuous exercise. Thus, if you can burn more fat while running, you save some glycogen so that, ultimately, you can run longer.
How does all this fit into losing body fat? You might think from this explanation that low-intensity exercises are better for fat loss, and in the end, weight loss. Actually, this is not true. Let me explain this common point of misunderstanding.
There is a rule when it comes to losing body fat: You must burn more calories than you eat. Doing so creates an energy deficit that prompts your body to take fat out of storage, and you lose weight. Any exercise burns calories, and any exercise can contribute to fat loss as long as you have an energy deficit over time.
While low-intensity exercises burn proportionately more body fat and high-intensity exercises burn mostly carbohydrate, what your body burns as fuel after you work out also contributes to the fat-loss picture. Studies show that following high-intensity exercise, the body burns more fat to compensate for lost glycogen stores as they are being refilled and the body recovers from the tough exercise session. This revved-up fat burning may continue for more than 24 hours, depending upon the exercise effort. Also, high-intensity exercise burns more calories per minute than "slow" activities. So you burn more calories in the time you dedicate to exercising, which can help when you're trying to lose weight.
The bottom line is when it comes to exercise and fat loss, any exercise will do, as long as you do it! Low-intensity exercises are easier to do, especially as you start a fitness program. And as you become more fit, you can boost the intensity for greater calorie burning per minute. So find an activity, or several to avoid boredom, and enjoy your fitness and improved health.