My mentor, the late great nutritionist Robert Crayhon, used to say this: "The two great dangers with nutrition are thinking it does too much, and thinking it does too little."
The same can be said of exercise.
This article is about exercise. And about weight loss. And about the relationship between the two. Which, sad to say, is probably a very different relationship than you might think.
Now before we get started, a disclaimer. I exercise regularly. I think you should too, no matter who you are. I think exercise is the greatest anti-aging activity on the planet. And the data are clear: Exercise can help with depression, lower the risk for heart disease and cancer, and reduce the risk and complications of diabetes. It can even grow new brain cells.
What it can't do is cause you to lose weight.
(I told you this was news you didn't want to hear.)
In a new book called The Cure For Everything: Untangling Twisted Messages About Health, Fitness and Happiness, Timothy Caulfield summarizes the data on fitness and exercise, and takes apart some of the common myths associated it. And the news ain't good.
Although the benefits of exercise are legion and well-documented, the fact is that most people exercise for vanity reasons, not primarily for health. Weight control and looks top the list of every client I ever worked with back in the days when I was a trainer at Equinox, and they continue to top the goal list of gym members everywhere. (Sure, everyone gives lip service to heart health, but most people secretly just want six-packs.) So here -- in Caulfield's terms -- is "a crummy dose of reality": It's horribly difficult to seriously change the way you look through exercise alone.
Sure, there are tons of exceptions, and you'll see them in "before" and "after" pictures in dozens of infomercials and print ads for weight-loss products, though the fine print always says "results not typical." And that's precisely the point -- those results are very far from typical.
For every person who managed to make the annual weight-loss issue of People magazine, for every healthy guy smilingly holding up an old pair of pants twice the size of Cleveland, for every 100-pound-lighter winner of The Biggest Loser, there are thousands more who lose, regain, lose, regain, give up and essentially look the same year in and year out.
If exercising alone could produce weight loss, we'd be a whole lot skinnier as a nation and those "success" stories would be far more common.
In general, and in the long run, as Caulfield notes, "The data simply does not support the use of exercise as a primary tool for getting thin." Here's Caulfield quoting Todd Miller, professor in the Department of Exercise Science at George Washington University: "People don't understand that it is very difficult to exercise enough to lose weight. If that is why you are doing it, you are going to fail".
The idea that exercise causes weight loss is firmly embedded in our national consciousness, and is accepted as a basic truth even by people who don't exercise. One reason is the widely-accepted theory that weight loss is all about calories.
According to the theory, weight loss is all about calories in, calories out. (There are more than a few problems with this hugely out-of-date oversimplification, but let's just go with it for a minute.) Since exercise burns calories, it stands to reason that all things being equal, exercise should cause weight loss. After all, if you burn more calories than you take in, you'll lose weight, and since you burn "a ton" of calories during exercise, the pounds should just melt off.
Good luck with that.
For one thing, you don't burn a ton of calories during exercise, unless you're Michael Phelps. Fact is, you only burn about 300 calories a half-hour, if that -- a calorie "deficit" that is almost immediately wiped out by a couple of Gatorades, let alone one mocha low-fat latte or a "low-fat bran muffin." (Don't believe for a minute the calorie readouts on the exercise machines at your gym -- those manufacturers have an interest in overstating the calorie number, making you think you're burning a ton of calories by using their devices.)
Problem number two is the phrase "all things being equal." They're not. The calorie math works great if you eat the same amount of food but increase the number of calories you "burn," creating a calorie deficit. But most people don't. Mounting evidence suggests that exercise makes us hungry and that we wind up eating more extra calories in response to that hunger than we "burn up" doing the exercise that made us hungry in the first place.
Caulfield calls out those among us -- you know who you are, my friends -- who are fond of saying things like "I work out so I can eat what I want." Umm... not so much. As trainers are fond of saying, "You can't out-train a bad diet." Knocking out 300-600 calories on the stairclimber doesn't begin to "compensate" for a supersized fries and a medium shake, nor even the most modest dish at El Torito or Olive Garden. So sure, working out may allow you to "eat whatever you want" if whatever you want to eat is limited to meat and broccoli. But if you think that hour in aerobics class bought you a free pass at the all-you-can-eat pasta station at the Bellagio buffet, you're delusional.
But exercise does have a relationship to weight -- it's just not as perfect a relationship as most of us would like. While exercise by itself is fairly useless for losing weight, it appears to be critical to keeping the weight off once you've lost it. But to do that, you may have to work harder or longer than you thought.
A study in the Journal of the American Medical Association followed the exercise habits of over 34,000 women and concluded that it took about an hour a day of moderate (3 mph walking) exercising to maintain weight. This research supports the findings of the National Weight Control Registry, which reports that 90 percent of people who have successfully lost weight and kept it off exercise on average for an hour a day.
Now that sounds like a lot. But remember that nearly all of this research focuses on moderate-intensity exercise like walking. And walking is fine -- for all the health benefits mentioned above -- but it's pretty inefficient for weight loss.
A much better and more efficient way to exercise -- and one that research is clearly showing works a lot better -- is to do high-intensity circuit training. Put the beauty bells down and lift some iron. Shorten your rest periods. If you're doing "aerobics," do some interval training where you sprint for a while then jog to catch your breath.
And by the way, forget about "toning." It doesn't exist. You're either building muscle, maintaining the muscle you already have, or your muscles are slowly shrinking. The first two are accomplished with weight that's heavy to lift. The third is accomplished by doing nothing.
Please understand: No one believes in exercise more than I do. But trying to lose weight with exercise alone -- particularly the long, slow, arduous and generally not-fun method of running mindlessly on a treadmill -- is a doomed strategy if your goal is to lose body fat.
Here's a much better strategy:
One: Revamp your diet, concentrating on carbohydrates. Carbohydrates -- particularly sugar, soft drinks and starches like potatoes, rice, pasta, bread, cereals and crackers -- drive levels of insulin, your "fat storage" hormone, through the roof, which makes it brutally hard to lose body fat. Eat more protein and fat, get your carbs from vegetables and fruits, and eat less of everything.
Two: Exercise regularly, but exercise smart. Increase the intensity and shorten the time. Circuit and interval training are the modalities that have trainers and exercise physiologists the most excited these days when it comes to both health benefits and fat burning. Pay attention -- they're right!
Three: Recognize that fitness and six-pack abs aren't the same thing. Exercise for fitness and for health, and to maintain your gains. But don't expect your morning walk to transform your body, especially if you don't take serious aim at your diet.
Eric Ravussin, professor at the Pennington Biomedical Research Center in Baton Rouge, La. and an expert on weight loss, put it best: "In general, exercise by itself is pretty useless for weight loss."
But -- as Robert Crayhon would have reminded us -- that hardly means it's useless for anything.
For more by Dr. Jonny Bowden, click here.
For more on fitness and exercise, click here.
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more