2012-08-01

Sorry, Gretchen. Exercise Matters.


I have previously claimed that exercise is just as important as diet when it comes to health and fitness. (See a brief previous post here.)

Today's online New York Times has an article by one Gretchen Reynolds that reiterates what has become a recurring them at the Times and elsewhere, with respect to health and fitness. I quote (with omissions omitted and emphasis added):
[I]n a just world, frequent physical activity should make us slim. But repeated studies have shown that many people who begin an exercise program lose little or no weight. Some gain.

...

The implication, the scientists concluded, is that “active, ‘traditional’ lifestyles may not protect against obesity if diets change to promote increased caloric consumption.” That is, even active people will pack on pounds if they eat like most of us in the West.

The underlying and rather disheartening message of that finding, of course, is that physical activity by itself is not going to make and keep you thin.
I am not particularly sure why this idea has taken root in the psyche of the pop-fitness world, but it is somewhat disconcerting. Over and over again, we hear that it is diet that determines whether or not we lose weight or remain thin. "Diet is more important than exercise," they tell us. "Diet is more significant than exercise," studies conclude.

The problem with this story is that, if we were to believe it, we would conclude that a healthy diet, along with some genetic factors, is what makes an elite athlete Olympic-caliber, while the rest of us are relegated to weekend-warrior status, or worse: obese. Told that way, the idea that you can "eat your way to the Olympics" is almost laughable. But is it true?

In an almost eerie coincidence, today's Wall Street Journal published an article about the extent to which Olympic athletes gorge themselves on junk food. That article opens with the following stunner: "U.S. swimmer Ryan Lochte ate McDonald's food for nearly every meal at the 2008 Olympics in Beijing and won four medals, including gold in the 200-meter backstroke."

The Journal article continues:
Among the oddities that distinguish Olympic athletes is their ability to massively consume the very foods everyone else is nagged to avoid.

The Olympic workouts of elite swimmers burn up thousands of calories and trigger training table menus that sound like the wish list for a kid's birthday party: Big Macs, Mountain Dew, Skittles, chocolate milk.
In contrast, here's Reynolds again, over at the Times:
“There’s this expectation that if you exercise, your metabolism won’t drop as you lose weight or will even speed up,” says Diana Thomas, a professor of mathematics at Montclair State University in New Jersey, who led the study.

But she says close mathematical scrutiny of past studies of exercise and weight loss shows that that happy prospect is, sad to say, unfounded. One of the few studies ever to have scrupulously monitored exercise, food intake and metabolic rates found that volunteers’ basal metabolic rates dropped as they lost weight, even though they exercised every day. As a result, although they were burning up to 500 calories during an exercise session, their total daily caloric burn was lower than it would have been had their metabolism remained unchanged, and they lost less weight than had been expected.
So, on the one hand we have Reynolds over at the Times telling us that the speed of a person's metabolism plays little to no role in health and fitness, that it all comes down to diet. On the other hand, we have Rachel Bachman over at the Journal telling us that Olympic athletes are able to burn through so many calories that the foods they consume end up being so unhealthy and calorie-dense that it is almost shocking.

One of these things must be true, and the other false. But which?

Getting To The Truth
Unless Bachman completely fabricated her story, the quotes she supplies from real Olympic athletes, in which they readily own up to their junk food diets suggests that it is possible to eat large amounts of a "Western diet" and be not only healthy, but world class. From my own experience, I can tell you that I never ate as much junk food as I did when I was competing in NCAA track and field. That this happens prevalently is an inarguable fact.

This flies in the face of Reynolds' assertion that "even active people will pack on pounds if they eat like most of us in the West." Olympic athletes, in point of fact, can retain their positions as the best athletes in the entire world while consuming diets that are far worse than what "most of us in the West" eat.

What Gives?
The answer to this apparent conundrum boils down to what you think makes a person an Olympic-caliber athlete.

To many of us, being an Olympic athlete means you were somehow blessed with superior genetics, that you contain a level of physical ability not possessed by "mere mortals." No "normal person" can ever hope to get to the Olympics, according to this logic, because the major determining factors are solely genetic. This genetic superiority further allows the godly Olympic competitors to consume whole large-sized pizzas without ever gaining a pound, while the rest of us would be sent to the hospital were we to attempt such a feast.

What role does training play in the development of an elite athlete? If diet is so much more significant a factor, why don't athletes spend more time tweaking their diets and less time training?

As those of us who have seriously competed in athletic events well know, training plays a big role in the development of an elite athlete. It takes years - decades - for a human being to reach a world-class level of athletic performance. Clearly, all that training and practicing has an impact; it doesn't all just come down to having good genes.

It's Not How You Exercise For The Next 3 Months - It's How You Exercise Forever
Earlier this year, researchers in Stockholm, Sweden observed that a 20-minute bout of exercise was sufficient to activate dorman genes for up to 48 hours, stimulating fat metabolism. (References are many, but try this Time Magazine article, for example.) They further discovered that the more intense the exercise, the greater was the "activation" of these genes.

That's one recent article. Here's an article from 2003, describing how aerobic exercise increased the "activity of muscle mitochondrial enzymes... and mRNA levels of mitochondrial genes... and genes involved in mitochondrial biogenesis...."

The truth of the matter is that one's genes are not a static thing. They change in response to exercise. And the more you build on your exercise regimen, the more your genes change.

You can't lift 15 pounds until you're capable of lifting 10. You can't lift 10 pounds until you're capable of lifting 5. If today you're not capable of lifting any amount of weight, you cannot get to the point where you can do a full gym-based weight routine until you first build your muscles to a certain point. Once there, you can build on your progress. The point here is that exercise isn't binary. It's not "either you exercise, or your don't." Instead, it's a question of how much you're exercising, what you're doing, how hard you push yourself. (Take, for example, this 2009 study showing that exercise intensity is significant when it comes to the health benefits of the exercise being performed.)

That's how it works for Olympic athletes, too. They start as young children, playing and competing in recreation-league sports, just like you did. We all started out with minimal ability, no technique, and merely a casual interest in the sport. Over time, we developed our abilities and tried to better them even further. But, where you reached a point where you were relatively satisfied with your performance level, elite athletes, pushed themselves further still. They kept training while the rest of us went to watch a movie. They had a keener interest and a greater dedication. Their physical abilities are a direct result of that dedication, and the resulting training it entailed.

Studies that examine the comparative roles of diet and exercise on cohorts of people always follow a group of people for between one month and two years. A lot can happen in such a period of time, but one thing we know for sure is that it takes many years of training for an elite athlete to become an Olympian.

Could it be that our friends at the time, such as Gretchen Reynolds, suffer from an insufficiently lengthy cognitive time-horizon?

The Bottom Line
Reynold's isn't a dolt, and I won't disagree with her on every point. If you have some weight to lose, you owe it to yourself to clean up your diet and take on an exercise regimen. If you have a lot of weight to lose, then you probably have significant changes to make to your diet, and those changes will have a more significant impact on your body than the daily walk you might decide to take.

However, the reason Olympic athletes can consume so much junk food without suffering negative repercussions is because they have been training very hard for a very long time. No change that you make to your diet will ever have as significant an impact on your overall health level as a decades-long dedication to physically demanding exercise will.

So, you can take the Times' advice and improve the quality of your diet for a quick bang if you're looking to lose a few pounds. But if you think you're going to become a healthy person just by eating a good diet, you're fooling yourself. Real health comes from good, hard exercise.

Just as Olympic athletes don't make it to the Games without years of hard training, you'll never reach a real and appreciable level of overall health unless you push yourself hard with intense exercise for years on end. We all want a silver bullet, but there just isn't one. If you want to be healthy, you have to do healthy things.