The 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. We get our energy from fat, carbs and protein but. Which one our bodies draw from, however, depends on the kind of activity we're doing. Now, most people want to use fat for energy, which makes sense. We figure, the more fat we can use as fuel, the less fat we'll have in our bodies. 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:
The body primarily uses fat and carbs 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 exercise, 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. And, 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? Just because you're using more fat as energy doesn't mean you're burning more calories.
The Myth of the Fat Burning Zone
One thing we know is that exercising at lower intensities will use more fat for energy. This basic premise is what started the theory of the 'fat burning zone,' or 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.
Does this mean that, if you want to burn more fat, you should avoid low intensity exercise? Not necessarily. There are some specific things you can do to burn more fat and it all starts with how and how much you exercise.
Fat Burning Tip #1: Incorporate a Mix of Low, Medium and High Intensity Cardio Exercise
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.
High Intensity Cardio
For our purposes here, high intensity cardio falls between about 75 to 85 of your maximum heart rate (MHR) or, if you're not using heart rate zones, about a 6 to 8 on this perceived exertion scale. What this translates to is exercise at a level that feels challenging and leaves you too breathless to talk much. 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-lb. person would burn about 225 calories after running at 6 mph for 30 minutes. If this person walked at 3.5 mph for that same length of time, he would burn 85 to 90 calories. But, the number of calories you can burn isn't the whole story. If you do too many high intensity workouts every week, you risk:
Overuse injuries
Burnout
Inconsistent workouts
Growing to hate exercise
Not only that but, if you don't have much experience with exercise, you may not have the conditioning or the desire for breathless and challenging workouts. And if you have some kind of medical condition or injury, forget about doing high intensity training (or any kind of training) without checking with your doctor first.
If you're doing several days of cardio each week, which is what is recommended for weight loss, you would probably want just 1 or 2 workouts to fall into the high intensity range. You can use other workouts to target different areas of fitness (like endurance) and allow your body to recover.
Some examples of high intensity workouts:
A 20-minute workout at a fast pace
You can use any activity or machine, but the idea is to stay in the high intensity work zone throughout the workout. You'll find that 20 minutes is usually the recommended length for this kind of workout and most people wouldn't want to go much longer than that.Interval Training
A great way to incorporate high intensity training without doing it continuously is by doing intervals. Alternate a hard segment (e.g., running at a fast pace for 30 to 60 seconds) with a recovery segment (e.g., walking for 1 to 2 minutes). Repeat this series for the length of the workout, usually around 20 to 30 minutes. You can learn more in my Interval Training Workouts.
Moderate Intensity Cardio
There are a variety of definitions of what moderate intensity exercise is, but it typically falls between about 60 to 70 of your MHR (a level 4 to 6 on this perceived exertion scale). The American College of Sports Medicine (ACSM) often recommends this level of intensity in its exercise guidelines. The lower end of this range usually incorporates the 'fat burning zone.' That means can carry on a conversation without much difficulty and you feel pretty comfortable with what you're doing.
Moderate intensity workouts have some great benefits such as:
Comfort -- Hard workouts are, well, hard. It takes time to build up the endurance and strength to handle challenging exercise. Moderate workouts allow you to work at a more comfortable pace, which means you may be more consistent with your program.
Better health -- Even modest movement can improve your fitness while lowering your risk of heart disease, diabetes and high blood pressure.
More choices -- High intensity workouts will usually involve some kind of impact or, at the least, a fast pace. But, you can usually get up into the more moderate heart rate zones with a variety of activities, providing you work hard enough. Even raking leaves or shoveling snow, if you do it vigorously enough, can fall into that category.
For weight loss purposes, you would likely want the majority of your cardio workouts to fall into this range. Some examples:
Walking 10,000 steps a day
A 30 to 45-minute cardio machine workout
A brisk walk
Riding a bike at a medium pace
Low Intensity Activity
Low intensity exercise is considered to be below about 50 to 55 of your MHR, or about a level 3 to 5 on this perceived exertion scale. This level of intensity is no doubt one of the more comfortable areas of exercise, keeping you at a pace that isn't too taxing and doesn't pose much of a challenge. This, along with the idea that it burns more fat, makes this a popular place to stay. But, as we've learned, you can burn more calories if you work harder, and that's what you want for weight loss.
That doesn't mean that low intensity exercise has no purpose. It involves the kind of long, slow activities you feel like you could do all day and, even better, activities you usually enjoy such as:
Taking a stroll
Light gardening
A long, slow bike ride
A gentle stretching routine
This doesn't have to be a structured, scheduled workout, but something you do all day long by walking more, taking the stairs, doing more physical chores around the house, etc.
Fat Burning Tip #2: Exercise Consistently
It may seem like a no-brainer that regular exercise can help you burn fat and lose weight. But, it's not just about the calories you're burning. It's also about the adaptations your body makes when you exercise on a regular basis. Many of those adaptations lead directly to your ability to burn more fat without even trying. When you exercise regularly, your body:
Becomes more efficient at delivering and extracting oxygen -- Simply put, this helps your cells burn fat more efficiently.
Has better circulation -- This allows the fatty acids to move more efficiently through the blood and into the muscle. That means fat is more readily available for fueling the body.
Increases the number and size of mitochondria, also known as cellular power plants that provide energy for the body.
And, don't forget, regular exercise will also help you manage your weight. The more activity you engage in, the more calories you'll burn, and the easier it is to create the calorie deficit needed to lose weight.
Tips for Consistent Exercise
Schedule some exercise time every day, even if it's just a few minutes.
Split up your workouts. You can get the same benefit from short workouts spread throughout the day as do with continuous workouts.
Change daily routines to incorporate activity. Park at the edge of the parking lot at work to add more walking time, or add an extra lap at the mall when shopping. Integrating more activity into your usual routines will help you stay active, even if you don't have time for a structured workout.
Make exercise your focus and schedule the rest of your day around it instead of trying to squeeze it in when you can. If it's not a priority, you won't do it.
Exercise Resources
Fat Burning Tip #3: Lift Weights
Adding more muscle by lifting weights can also help with burning fat, especially if you're also dieting. Lifting weights:
Preserves muscle mass -- If you diet to lose weight, you actually risk losing muscle as well as fat. Muscle is metabolically active, so when you lose it, you also lose the extra calorie-burn muscles can provide.
Keeps your metabolism going -- Some studies have found that a diet-only approach to weight loss could lower a person's resting metabolic rate by up to 20% a day. Lifting weights and maintaining muscle helps keep the metabolism up, even if you're cutting your calories.
Helps you burn extra calories -- If you lift weights at a higher intensity, you can actually increase your afterburn, or the calories you burn after your workout. As About.com Weight Training Guide Paul Rogers states in his article, Burn More Fat, "If you can get afterburn...that’s a bonus because you burn fat during the exercise and after you cease as well."
Strength Training Resources
There's no way around the fact that, when it comes to burning more fat, we have to work at it. There is no magic exercise, workout or pill that will do the job for us. But, the good news is that it doesn't take much activity to push the body into that fat burning mode. Try incorporating some type of activity every day, even if it's just a quick walk, and build on that over time as it becomes more of a routine. Do that and you're on the way to burning more fat.
Sources:
Kinucan, Paige and Kravitz, Len. "Controversies in Metabolism." www.drlenkravitz.com. Retrieved Oct. 3, 2007.
Kravitz, Len. "Fat Facts." IDEA Fitness Journal, Sept. 2007.
Thompson, D.L. et al. "Substrate use during and following moderate- and low-intensity exercise: Implications for weight control." European Journal of Applied Physiology and Occupational Physiology 1998; 78(1), 43-49.
