"Afterburn" Under Fire

Why, O why, aren't readers of MPF consulted when the guys in white coats design studies on fitness and weight loss?

The New York Times recently published an article detailing a study on, among other things, the "afterburn" effect--a.k.a., EPOC, or Excess Post-Exercise Oxygen Consumption, or, as everyone reading this probably knows, the body's tendency to burn more calories in the hours, and sometimes days, following an intense exercise session.

The study was set up to compare the number of calories burnt during and after exercise by lean endurance athletes, and by two groups of sedentary people, one lean, one obese, and claimed to test the theory that endurance athletes' metabolisms tended to burn fat calories preferentially over carbohydrates.  

Here was the setup:

Each of Melanson’s subjects spent 24 quiet hours in the calorimeter, followed later by another 24 hours that included an hourlong bout of stationary bicycling. The cycling was deliberately performed at a relatively easy intensity (about 55 percent of each person’s predetermined aerobic capacity). It is well known physiologically that, while high-intensity exercise demands mostly carbohydrate calories (since carbohydrates can quickly reach the bloodstream and, from there, laboring muscles), low-intensity exercise prompts the body to burn at least some stored fat. All of the subjects ate three meals a day. 

To their surprise, the researchers found that none of the groups, including the athletes, experienced "afterburn." They did not use additional body fat on the day when they exercised. In fact, most of the subjects burned slightly less fat over the 24-hour study period when they exercised than when they did not.

Anyone want to hazard a guess as to why no one experienced EPOC?

That's right, Jimmy:  it's due to the low intensity of the exercise they performed.  Had the subjects done high-intensity anaerobic work like sprinting or circuit weight training, all previous studies suggest that their metabolisms would have been elevated in the hours following exercise.  Again and again, moderately-paced exercise has been shown not to raise metabolism except during the exercise session itself, leading to thousands of comparisons of the physiques of skinny marathoners and ultra-lean, muscular sprinters.  

So this study missed the boat:  the subjects should have been exercising more intensely.

Why did these guys so fully miss the boat on this one? 

As ever, there is a discrepancy between "street" knowledge (accrued through the amassing of anecdotal evidence by bodybuilders and athletes whose livelihood depends on leanness and muscularity) and "lab" knowledge.  The state of the latter runs way behind the state of the former.  In part that's probably because whoever created this study most likely came up with the parameters a zillion years ago--prior to all the evidence on EPOC and high-intensity exercise--scraped together the funding, found some willing subjects, wrote the paper, had it vetted by all his peers, and then published it, long after he very well might have realized that he was chasing the wrong rabbit.

The article concludes, in effect, that EPOC is a fallacy, and that we're left, once again, with a "Calories In, Calories Out" formula for weight loss.  This advice is about as useful as saying to a losing football squad,  "Come on guys, just score more points than the other team!" 

Of course it's calories in, calories out.  No one ever argued that calories could magically disappear. The question is how to get the metabolism to burn the MOST calories with a MINIMUM investment of time--which everyone is short on.  And the answer, apparently, is high-intensity exercise.

Not to pick on the much-vaunted New York Times, which gives my sister her livelihood, but why are they running so far behind the state of the art and publishing the results of such studies as if they are breaking news?