Burn Fat Faster with Interval Training
THE BEST WORKOUT for burning fat is something called interval training. Interval training is nothing more than the incorporation of short bursts of high-intensity exercise (intervals) into your regular workout.
It’s easy to do. If you’re walking for an hour, try interspersing short 30 second runs every few minutes. If you’re already running, try sprinting faster for 30 seconds. The idea is to alternate these “intervals” of super-hard exercise with more moderate exercise (called “active rest”), during which you catch your breath and get ready to repeat the whole process.
Interval training allows you to maximize the results of your workout, lose more fat, and get fitter, all at the same time. There’s no more powerful type of exercise for fat loss on the planet.
Research on interval training and its benefits for both aerobic fitness and fat loss have been going on for decades, but one of the most recent studies was done by an exercise physiologist at the University of Guelph in Ontario, Canada, named Jason Talanian.
“We’ve always assumed that if you’re not too fit you should just get on the bike and go for an hour,” Talanian told me in an interview. “But our research has shown really powerful improvements in overall fitness and in fat burning when you increase the intensity for specific intervals.”
Doing these spurts of high-intensity exercise leads to physiological adaptations that literally help us burn fat. Specific enzymes in the mitochondria—the powerhouse energy-burning factory in the cell nucleus—become more active through this kind of training. These enzymes—specifically, citrate cynthase and beta-hydroxyacyl-CoA dehydrogenase—break larger fatty acids down into smaller ones.
“This makes it easier to actually burn fat,” Talanian says. Besides actual fat burning, measures of cardiovascular fitness—such as maximum oxygen capacity (known as VO2 max)—also improve significantly with this kind of training.
In Talanian’s study, published in the April 2007 Journal of Applied Physiology, eight university-age women worked out in his laboratory every other day for two weeks, for a total of seven sessions. During each workout, they performed ten high-intensity intervals of four minutes each. In between each interval they would have two minutes of rest time.
The women were all over the map when it came to fitness levels. Some were completely sedentary, but one was a triathlete and another was a competitive soccer player. The rest were of average fitness and had been exercising in a conventional manner prior to the study (three times a week or so, moderate intensity, kind of what I normally see at the local gym).
“Regardless of their beginning fitness level, all were able to complete at least seven of the ten intervals,” Talanian told me. “It was completely doable. And in all subjects we saw increases in the (structures) that escort the fat into the mitochondria where [it] can be burned for energy.”
Talanian’s study was unusual in that the “high-intensity” intervals were quite long—four minutes each. In previous studies, the “hard” intervals were typically thirty seconds, followed by a lower-intensity, active rest period of two to three minutes. So, for example, if you were walking, you’d speed walk (or run) for your thirty-second interval, and then continue walking (active rest) for two to three minutes while your heart rate slowed a bit. You could repeat that sequence up to ten times per workout.
Talanian hypothesized that one of the reasons for the impressive results in his study was indeed the longer interval of high-intensity work. “I think it’s possible that the aerobic component—the last two minutes of the interval—has a lot to do with why we’re seeing such adaptations in fat burning.”
If four-minute intervals of high intensity seem daunting to you, don’t despair. You can get the benefits of interval training with much shorter intervals. One earlier study at McMaster University in Ontario, Canada, found that only four to seven “all-out” bouts of thirty seconds each, alternating with a full, four-minute “recovery” period, still doubled the endurance capacity of the subjects in a mere two weeks of training.
Talanian suggests starting your interval training by computing your maximum heart rate (220 minus your age) and then shooting for a high-intensity interval of 80 percent of that maximum. (You can, of course, work up to that, and you can also start with shorter intervals and increase to longer ones as you improve.)
Most people can’t sustain high-intensity exercise for long periods of time. However, we can easily sustain it for thirty seconds to four minutes. By mixing those “high-intensity” intervals into the workout, we’re increasing the number of calories burned for the same amount of time.
One of my favorite docs in the country, Al Sears, M.D., C.N.S., has written an entire program based on fat loss through interval training. It’s called PACE (Progressively Accelerating Cardiopulmonary Exertion—a fancy way of saying interval training). Sears—a bit of a contrarian, but a brilliant one—goes so far as to call what most people call “cardio” exercise a waste of time. He believes that forced, continuous endurance exercise induces your heart and lungs to “downsize” because smaller organs allow you to go further, more efficiently, with less rest and less fuel. What’s wrong with that, you might ask?
“Instead of building heart strength, (long, slow endurance exercise) robs (the heart) of vital reserve capacity. Heart attacks don’t occur because of a lack of endurance. They occur when there is a sudden increase in cardiac demand that exceeds your heart’s capacity,” he says. Sears believes that short bursts of high-intensity exercise create not just a reserve for your heart, but a hormonal environment conducive to fat loss.
If you still doubt this, ask yourself when you last saw a flabby sprinter. Flabby marathoner? Maybe. Sprinter? Never.
You can start PACE with an easy, ten-minute program. After warming up, spend one minute working hard enough to break a sweat and give your heart and lungs a challenge. Then slow down and let your heart rate recover for another minute. Repeat. Alternate one minute of exertion with one minute of recovery five times, for a total of 10 minutes. It’s a great way to start interval training and really begin to lose the fat.
And your heart will thank you for it at the same time.