TCS Daily

Getting Exercised About Exercise

By Sandy Szwarc - January 8, 2004 12:00 AM

To combat the obesity epidemic our government wants us to get into shape. Former U.S. Surgeon General C. Everett Koop's Shape Up America! has been updated with Shape Up & Drop 10™ and Surgeon General David Satcher's 10,000 Steps Program. A multitude of other compulsory exercise programs targeting fat have also been instituted by major employers, schools and healthcare providers.

The shared goal of these exercise initiatives is weight loss. The underlying belief is that being "in shape" means being thin and no one would be fat if everyone exercised. For consumers, the take home message is that the whole point of exercise is to be thin. In fact, we're admonished everyday to exercise to lose weight.

Trouble is, exercise - as necessary as it is for us -- won't make us thin.

"I think fitness and medical professionals are doing a disservice to their clients when they position exercise as a way to lose weight," said Jennifer Portnick, personal trainer and certified aerobic exercise instructor at Feeling Good Fitness in the Bay area. "Becoming active may or may not result in a change in weight."

But few of us realize that the most significant body of research shows exercise doesn't appreciably change body weights at all.

Recognizing that many of the studies finding beneficial weight loss due to exercise were not well controlled, researchers at the University of Texas conducted the Heritage Family Study. Led by Jack H. Wilmore, Ph.D., they put over 500 men and women on a 20-week endurance training program. While concluding that exercise can induce favorable changes, the study admitted they're of "limited biological significance." Yet the researchers speculated that increasing the intensity and duration of exercise would "likely have a major effect on body-composition and fat distribution." (As we'll see, that hopeful prediction didn't prove out.)

Just how "limited" were the weight loss benefits of exercise? Men lost 0.4 kg and women a mere 0.1 kg! Other research, such as the meta-analysis done by researchers at the University of Vermont, has consistently found women lose less fat and weight than men, an understandably important biological attribute for preserving fertility and the survival of the species. "In a recent study conducted in our laboratory," wrote Wilmore, "previously sedentary, moderately overweight women placed on an intense, 6-month, resistance-training program actually gained total mass and fat mass, even though they were instructed to maintain the same diet and activity pattern that they had before starting the study."

Yes, many studies have found women actually gain weight and body fat with exercise. In another study in which obese women did 6 months of aerobic exercise 4 to 5 times a week, one-third of them gained as much as 15 pounds of body fat, with the average of the gainers being 8 pounds. That's body FAT, not weight, emphasized Glenn Gaesser, Ph.D., associate professor of exercise physiology at the University of Virginia, a Fellow of the American College of Sports Medicine and author of Big Fat Lies: The Truth About Your Weight and Your Health (Gurze Books, 2002). "Just to make it clear that the weight gain was not muscle, as fitness buffs might assert. Thus a true skeptic might ask whether "exercise" has contributed to the obesity epidemic!!"

Another study just released provides some especially poignant data. The Midwest Exercise Trial led by Joseph E. Donnelly, EdD put men and women on a 16 month-long, intensive exercise regimen (at 60 to 75% of their maximum heart rate, to burn about 2,000 kcal per week). While men lost about 5 kg and 3.7% body fat, women gained 0.6 kg of body weight while losing a mere 0.2 kg body fat. It makes for some rather interesting math, noted Gaesser. The women each burned about 138,000 total kcal during those 69 weeks, or about 313,636 kcal per pound of fat!

It sort of flies in the face of that simplistic myth -- "burn 3,500 kcalories and lose a pound" -- doesn't it?

"At about 80 kcal/mile for a 77 kg person walking at a reasonable speed (3 to 4 mph)," said Gaesser, the calories expended in this study "work out to roughly 3,920 miles per pound, equivalent to walking from New York City to Seattle, and then down to San Diego...for one pound of fat [lost]!"

My advice: Leave your pedometer at home, it probably can't count that many steps.

But did the public get this information? Hardly. Just imagine the headlines: "Exercise for 16 months ladies and gain a pound!" That would hardly sell treadmills, let alone costly anti-obesity exercise programs targeting fat people. Instead, "the authors tried to put the best spin possible on their results," said Gaesser. Their conclusion: "Moderate-intensity exercise sustained for 16 months is effective for weight management in young adults."

"We have a long way to go before we see exercise as anything but a means to weight loss in our culture," said Portnick. Despite the facts, exercise programs being instituted at schools, workplaces and healthcare institutions are invariably about addressing obesity, and success and compliance is judged by weigh-ins.

But, it is impossible to tell if and how much someone exercises by their weight.

"The difference in average BMI [body mass index] from the most sedentary to the most active is never more than 1 to 2 BMI units and usually less," said Gaesser. For example, the Women's Health Study, a cohort study of 39,372 women, evaluated the effects of various intensities of exercise and found the BMIs between those at the lowest and highest levels of exercise differed about 0.4. For an average 5 foot 4-inch woman, that's about 3 pounds, he said.

The same goes for men. The Harvard Alumni Study of 12,516 men found "that across an even greater range of reported weekly physical activity the difference in average BMI is negligible (less than about 5 pounds for men of average height)," Gaesser said.

Clearly, even the most active, no matter how hard they exercise, can't exercise themselves into the so-called "normal" weight range. "If everyone exercised, there would still be a wide range of individual body sizes and shapes," said Steven Blair, PED, President and CEO of the Cooper Institute in Dallas and renowned exercise researcher. "There is a genetic component for weight, just as there is for height."

Sadly, most people view themselves and others as failures if they don't lose weight with exercise, thinking if they just tried harder they wouldn't still be fat. It leads to obsessive weight loss behaviors that limit the full enjoyment of life, according to Marilyn Wann, noted proponent of healthy lifestyles for people of all size, editor of and author of Fat!So? (Ten Speed Press, 1998). "This mania leads to a kind of panicky feeling that I'm not okay the way I am, and that thought becomes instantly recognizable to me as part of fat hatred, not part of a happy, healthy life."

In Part Two, we'll look at other myths about exercise and who's really exercising in our country and who's not.


1 Comment

Oh No. Interesting Possibility...
I weigh about 200 now. Just went to the gym today and felt my body fat jiggling. That's pretty personal but I bet I'm not the only one. I'd like to weigh 160; too heavy by actuarial tables but it would be just good enough for my joints. I'm told I need to get my heart rate up to 140 and keep it there for, what...20 minutes. That means warming up and taking ten or fifteen minutes to work up to that pace. Exercise makes me feel more able to balance and to move freely. When I really knock myself out at the gym, I come out feeling exhausted. But when I go and get the old circulation going, I feel energized. It seems to me that, if you have to work so very hard to lose weight, and stay at it, then I'm just going to have to stay fat.

Now there are suggestions that workouts make you fatter. That makes sense to me because, if your paleolithic body eats your muscles when you starve yourself, because fat is worth more over time, then why wouldn't your body be programmed to see sustained exercise as another famine conditon? You have to go run extra far to catch that bison.

So, what makes the most sense is to adjust the sugar and fats down, stop eating to the "full" point and just eat enough, and eat more fiber. This isn't easy because the human animal will go for the sugar and fats.

Well, now the argument I'm making is at full circle. I guess you've got to try to "get a life" and stop being so into the food thing. When I'm doing something engaging like writing, I don't need food.

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