Running, burning fat and breaking myths
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Running, burning fat and breaking myths

This article first appeared in IMPACT magazine.

Some race for the sheer joy of it, while others see it as a proven method of not looking like the Michelin Man. He confesses that I am always looking for the definition of abs, which is not easy for a beer lover in his forties. While keeping an eye on what I eat is important, it’s the many miles of running each week that gives me a barely-there “four-pack.”

Because one of my motivators for running is weight maintenance, I’ve come across numerous myths about how to run to optimize fat burning. There’s no shortage of “secret” weight loss techniques that supposedly “turn your metabolism into an unstoppable fat burning furnace.”

Yes of course.

If you want to be successful at running in the long run, it’s critical to love what you’re doing and not just think of it as a means to an end. However, realistically, many of us want to look good, and running is one of the best exercises for burning fat. I can love it better when I know it’s helping to wash out some of the beer and pizza I inhaled the night before. So what is the best way to run if you want to lose weight? There are some caveats, like your skill level and injury prevention, but once you factor those things in, the advice is simple: run as fast as you can for as long as you can.

There you have Lost Class.

On second thought, let’s break down a couple of those myths just for fun.

MYTH #1: The best way to burn fat is to keep your heart rate in the “fat burning zone.”

This is true, but completely irrelevant. Yes, you “oxidize” more body fat at moderate intensity levels and burn more carbohydrate fuel at higher intensities, but think of your energy stores as one big soup, and it all comes out as a wash.

If you’ve ever seen a heart rate graph on a treadmill, you’ll have read “fat burning zone” at a moderate heart rate (around 60 percent of maximum) and “cardio training zone” at a higher rate (75 percent of maximum or more). Those charts don’t lie, but they don’t tell the whole story either. In a 2005 article in the European Journal of Sport Science, researchers Stefan Bircher et al. measured rates of fat oxidation at intensity levels ranging from 25 to 85 percent VO2peak (85 percent VO2peak equals 90 percent of maximum heart rate) and determined that the highest level of fat oxidation was at 65 percent intensity. Fat burning became “negligible” at intensities above eighty-five percent because at the highest intensities we primarily burned carbohydrates for fuel. These facts lead many to believe that exercising at a moderate intensity increases fat burning. While technically factual, it ignores the big picture.

Ironically, fat loss is not about using fat to fuel activity. It’s all about “calories in versus calories out,” which must be viewed from the perspective of what’s called the twenty-four hour energy balance. If your energy balance is negative (more calories burned than consumed), you lose weight; if your energy balance is positive, you gain weight. Yes, you can use more body fat for fuel while exercising at a moderate intensity, but in the grand scheme of the twenty-four hour energy balance equation, this means nothing. If you exercise to create an overall negative energy balance, you’ll burn those fat stores at some point in the day, whether you’re eating, sleeping, working, or doing…other things. The fact that the proportion of fat burned during moderate exercise was greater for fat than carbohydrate does not matter.

Having time to exercise is an important issue for many people. If you have forty minutes in your schedule and want to maximize calories burned, choose the fastest pace you can handle during that time. Given enough time, this equation shifts to a balancing act in finding a challenging but sustainable intensity level: The aforementioned Bircher research found that the majority of total calories were burned at a seventy-five percent intensity level.

It’s important to note that metabolism increases on a sliding scale the higher the intensity, so you burn more calories running 5K than you do walking or slow jogging the same 5K (and in less time).

There are other good reasons to run at a higher intensity: It improves your overall cardiovascular fitness level, making you more capable in other sports, and it’s better for raising HDL (good) cholesterol. Higher intensities also create a slightly higher caloric “afterburn”, which leads us to our next myth:

MYTH #2: Significant additional calories are burned through excess post-exercise oxygen consumption (EPOC).

The COPD myth states that after intense exercise, the metabolism remains elevated for an extended period of time and burns a significant amount of additional calories. COPD exists, but I refer to it as a myth because it has been exaggerated.

In a 2006 article in the Journal of Sports Sciences, researchers Joe LaForgia et al. found that more intense exercise creates higher EPOC, but still: “EPOC comprised only 6 to 15% of the total net oxygen cost of exercise.” For example, if you burn 1,000 total calories through prolonged, intense exercise, at most 150 calories come from COPD. What a thing.

Also, the better fit you are, the lower your EPOC will be because your body’s metabolism returns to normal more quickly. In 1990, researchers C. Gore and R. Withers reported in the Journal of Applied Physiology that in highly-fit people, EPOC could be as low as 1 percent and the median was 4.8 percent. If I fit that “average,” after a 12-mile run my EPOC calorie burn earns me a third of a beer. Let the good times pass!

This seems logical because the first time I tried to run my heart was pounding, my lungs were on fire, and for a long time afterward I felt like I was going to throw up my toenails. Now that I’m “trained” I recover faster, which means there’s not as much EPOC.

So what about high intensity interval training (HIIT)? It has been praised by many as the best fat burning method due to its supposed metabolic boosting effects. As I’ve already mentioned, EPOC has little consequence, even for intense exercise, so does interval participation change this dynamic in any way?

No, he does not do it.

Some advocate HIIT because of a 1994 article in Metabolism by Angelo Tremblay et al., but the study has been misrepresented through incomplete statistical analysis, and in reality, the amount of fat lost by participants using HIIT was negligible. Additionally, multiple research studies have shown that HIIT is no better than steady-state, high-intensity exercise for burning calories. If you do the same amount of exercise “work” (i.e., distance covered) in the same amount of time using a steady pace or through HIIT, you’ll burn almost the same number of calories, including the modest EPOC.

A quick survey of the research finds that Joe LaForgia et al. in 1997, William McGarvey et al. in 2005, and Nicolás Berger et al. in 2006, they all determined that HIIT did not provide a greater EPOC or other metabolic boost than steady-state aerobic activity of the same all-out intensity.

I personally don’t like HIIT because it lends itself to treadmills and I prefer running outside; the constant changes of pace interfere with my whole “Zen of running” experience. Additionally, HIIT can lead to injury in beginners and lead to burnout earlier even in trained athletes. Still, if it’s your thing, then there’s no reason to stop doing it. Additionally, there are benefits to integrating speed training into your run.

I often end my runs with a good sprint to come home out of breath, and this practice builds a useful skill. For example, a few years ago my son was riding a bicycle and his feet slipped off the pedals. He was heading straight for a parked truck and I ran after him at top speed, grabbing him by the back of his shirt and dragging him away just before I smashed his face into a pizza against the tailgate of an F-150. My wife witnessed it all and I earned huge hero points that day.

To conclude, the best pace to run is the one you like the most, the pace that keeps you lacing your shoes. Just don’t be afraid to push your limits if you want to burn more calories and therefore lose more fat.

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