For Canada’s obsese, exercise alone isn’t going to cut it
It’s such a widely accepted idea it’s virtually dieting dogma, a belief pushed with almost religious zeal: you can’t lose weight without exercising more.
But the story of Francina Kehoe, a B.C. woman who has battled obesity for years, highlights a growing body of research that shows what matters far more is how much we eat — not how much we move.
Early in the morning on Feb. 8, surgeons made five small incisions in Kehoe’s belly, inserted their long, thin instruments through the openings, and removed 85 per cent of her stomach.
The Langford mother of three had waited five years for her vertical gastric sleeve gastrectomy, a form of weight-loss surgery that, essentially, shrinks the stomach from the shape of sack to a thin tube. Six hours after the first surgery Kehoe required a second, this one to stop the internal bleeding. She endured a blood transfusion, elevated heart rate, swelling in her hands and arms, and spasms of post-surgical pain unlike anything she had felt before.
Kehoe weighed 267 pounds going into surgery. In 2002, when she was at her heaviest, she weighed 310 pounds. But even at 240 pounds, she could ski down a mountain or walk 10 kilometres. She admits there were times she was fitter than others, times when the sheer size of her body and the ache in her joints made exercise painful. But there were times, too, when she would exercise regularly, hitting the gym three to four times a week for months at a time. But the numbers on the scale never budged.
Kehoe is an extreme example of an overweight nation, a nation that has been taught exercise is a surefire path to weight loss. But controversy is growing over whether working out to lose weight can be an exercise in futility. At issue is whether the amount of exercise needed to make a meaningful impact on the prevalence of obesity is unrealistic and whether gluttony, and not sluggishness, is where we should be focusing our efforts.
According to the latest estimates from Statistics Canada, 37 per cent of the adult population aged 20 to 69 — 7.9 million people — are overweight, meaning they have a body mass index between 25 and 30. Another 24 per cent — 5.3 million — are obese, with a BMI of 30 or more.
Eric Ravussin, who is recognized internationally for his work in obesity and diabetes, says the amount of exercise needed to cause significant weight loss is more than most free-living individuals are capable of undertaking. In general, he says, that holds for anyone who has stepped onto a treadmill hoping to lose weight. “But it is more true for the obese because they could never achieve the level of exercise which could make a dent in weight loss.”
Moreover, Ravussin says, there is data to indicate that adding physical activity to food restriction produces only a modest amount of additional weight loss.
Experiments by University of Ottawa researchers suggest that people vastly overestimate how many calories they burn during a workout, and overcompensate by increasing their food intake after they exercise, especially when the workout is vigorous.
“Athletes have to eat 5,000 calories if they want to maintain their 10 kilometres a day of running. But we’re not talking about athletes, we’re talking about obese people,” says Ravussin, director of the Nutrition Obesity Research Centre at the Pennington Biomedical Research Centre in Baton Rouge.
“First of all, most of them hate exercise. Second, you need a lot of exercise, and a lot of time, to make a 200-, 300-, 400-calorie deficit, whereas you can easily make a 1,000 (calorie) deficit by cutting down your intake.”
Regular exercise reaps substantial health benefits, Ravussin stresses — better cardiovascular fitness, increased insulin sensitivity, lower blood pressure, lower cholesterol, less anxiety and depression, and a lower risk of early death and disease. He and others say physical activity is an essential determinant of health, and should be promoted for that very reason. It’s just not the best way to treat obesity.
And while governments across Canada have promoted school-based physical activity as a key part of the solution to childhood obesity, B.C. researchers who analyzed 18 of the best studies they could find that together involved more than 18,000 children found that, although they had other beneficial effects, school-based physical activity interventions didn’t improve BMI. Nor did they find any consistent changes in other measures of body composition, such as skin-fold thickness or waist circumference.
In a Time magazine cover story last summer, Ravussin stated that, “In general, for weight loss, exercise is pretty useless.” Colleagues were so startled they thought he must have been misquoted. The executive director of Ravussin’s research institute, Dr. Claude Bouchard, formerly of Quebec City Laval University, and a member of the Order of Canada, took to the institute’s website, posting a rebuttal arguing that it makes no difference to the human body whether it sheds calories via eating less or exercising more. The end result, Bouchard says, is the same: “Weight is lost.”
“So it may be easier to reduce your calories by eating less than by exercising more, but this does not mean exercise is ‘useless,’ he said.
Nor, he said, is he aware of any credible scientific proof that people eat with abandon after a workout, just because they believe they have earned the right to overindulge. “If the exercise is somewhat intensive, we see the opposite, there’s a depression of appetite,” Bouchard said in an interview. “You don’t want to eat.”
Ravussin is undeterred. He says the common belief that physical activity is a central solution to rising rates of obesity has become almost a religion. “It’s based on a belief rather than on solid scientific evidence.” He and others say governments and public health bodies need to focus on the food intake, or “calories in,” side of the “energy balance” equation, and less on “calories out.” “If you have been a couch potato for 45 years of your life it’s very unlikely you’re going to engage in a rigorous exercise program,” he argues.
“I know that if I stop exercising the way I do, I would gain weight, but this isn’t the issue. The issue is, how good is exercise for weight loss? And the answer to me is still, very lousy.”
Others beg to differ. Dr. Robert Ross, a leading exercise physiologist at Queen’s University in Kingston, Ont., says regular exercise can lead to significant reductions in abdominal fat, particularly visceral fat — fat that wraps around the intestines, liver and other organs that’s more dangerous and metabolically active than peripheral fat, the fat beneath the skin — even without significant weight loss. “Exercise mobilizes more fat from the abdominal region, and you get all the other benefits of physical activity,” says Ross, professor of kinesiology and health studies at Queen’s and director of Queen’s Centre for Obesity Research and Education. “You get none of that if you just calorically restrict,” he says. “I do not accept the notion that physical activity is useless as an obesity reduction strategy. That is simply not true.”
The problem, he says, is that the bathroom scale has become almost God-like; the single most important gauge we use to measure success.
“We have to take away this notion that physical activity is useful only if you achieve weight loss,” he says.
Statistics Canada says overall, 61 per cent of Canadian adults are overweight or obese. Not only are we fatter, we’re less fit and less flexible than we were a generation ago, according to a nationwide report released in January that led to predicted calls for “urgent action” to get Canadians moving more and sitting less. The Canadian Health Measures Survey was heralded as the most comprehensive national survey ever conducted that used direct physical measures of Canadians’ health. But, aside from asking people how frequently they ate certain foods, there was no information on quantity, or calorie intake.
And there’s the rub: few people appreciate the amount of physical activity required to compensate for even small amounts of food.
On average, people burn 100 calories for every mile (1.6 kilometres) they run or walk, the equivalent in calories to about half a plain tea biscuit from Tim Hortons.
Research suggests that, in order to return to the average weights of the 1970s, adults of today would have to lose 500 calories from their days. That’s roughly the equivalent of an additional home-cooked meal’s worth of calories. To lose 500 calories through exercise would require a daily eight-kilometre walk or run, or an hour of vigorous exercise such as rapid lap swimming or high-impact aerobics.
“It’s always disheartening to be on the treadmill at the gym and be sweating and sweating and sweating, and you realize, this is just 200 calories? It’s not even a candy bar,” says Amy Luke, an associate professor in the department of preventive medicine and epidemiology at Loyola University Chicago Stritch School of Medicine.
According to a recent article in the Journal of the American Medical Association, walking an extra mile a day expends, roughly, an extra 60 calories over sitting and doing nothing — the energy equivalent of a small cookie.
People can overcompensate for the calories burned during a typical workout before even leaving the gym. The Dairy Farmers of Canada recently began promoting low-fat chocolate milk as a post-exercise recovery and re-hydration drink, based on studies suggesting that the protein found in chocolate milk, but not in commercial sports drinks, helps recharge muscles.
One 500 ml carton of 1 per cent chocolate milk contains 332 calories.
“For the vast majority of gym-goers that would be about an hour’s worth of exercise,” says Dr. Yoni Freedhoff, an Ottawa doctor who runs an obesity treatment clinic. “So, at best, you’re breaking even. At worst, you come out behind.”
Current recommendations hold that, in order to lose weight, people need to engage in 60 to 90 minutes of low- to moderate-intensity exercise every day of the week. ‘Putting aside the fact most people aren’t inclined to exercise that much, many of us just can’t exercise that much,” Freedhoff says.
“Sadly, many public health officials still focus on exercise as being the single most important thing to focus on. Public health goes out of its way not to talk about calories. Our food guide gives zero guidance on calories, aside from saying, ‘don’t eat too many of them.’ People want to believe it’s all about exercise. But exercise doesn’t impact on weight to the degree that anybody would want, expect or hope for.”
When researchers recently compared different levels of exercise among 464 sedentary, overweight, post-menopausal women, they found that, after six months, women who exercised the hardest (190 minutes per week) lost virtually the same amount of weight as those who exercised the least (72 minutes per week). Even women assigned to the “non-exercise” control group lost about the same amount of weight as the women who worked out, roughly two to five pounds.
More startling, the 190-minute-a-week group lost about half as much weight as researchers predicted they would.
“I think it was because they were rewarding themselves,” says lead author Dr. Timothy Church, a medical doctor and professor of preventive medicine at Pennington Biomedical Research Center at Louisiana State University. “That’s what we heard anecdotally: ‘Man, I’ve made all my sessions this week. The wheels are off, I’m going to have a big dinner.’” The women weren’t told to change their diet. It was purely an exercise study.
In an elegantly simple study, University of Ottawa researchers put volunteers on a treadmill and “blinded” them to any time cues or numbers that would tell them the amount of calories they were burning. At the end of the workouts, they were asked for their best educated guess.
They overestimated their caloric expenditure, by fourfold.
“Next, we laid out all sorts of food in front of them and said, ‘Just eat how much you think you spent,” says Eric Doucet, a professor in the school of human kinetics at the U of O.
They ate, on average, about 650 calories, even though they had burned just 200 calories on the treadmill.
The study involved volunteers from the human kinetics department — people who specialize in physical activity and health.
People exercise and think they’ve earned extra eating because of it, Doucet explains. From an evolutionary standpoint, it makes sense. “If you’re out there hunting for food, you want to be sure you eat as much food as possible when you catch it. Over-consuming food after exercise makes total sense, to prepare yourself for what’s coming next.”
Researchers also point to homeostatic energy balance, where the body tries to maintain a given weight, especially when that weight is elevated. Neuropeptides in the brain tell the body, “You have just depleted 300 calories. Now put them back in.”
When people embark on a very-low-calorie diet, diets of no more than 800 calories a day, the body responds by lowering its resting metabolic rate, to conserve energy. Calories are burned more slowly. It’s what helped our ancestors survive famine. “It’s trying to defend that body weight by decreasing the energy expenditure,” Luke says. “That is undoubtedly being driven by brain chemistry.”
The same may hold true for exercise. “If our brain is sensing that we’re burning too many calories, or more calories than it would take to stay at a stable weight, it may very well be that it’s triggering brain chemicals to increase our appetite, or decrease our satiety. So, we go out and eat more calories. It doesn’t take much to throw that out of balance.”
Others argue that few people who exercise regularly are overweight, meaning that, if the “exercise makes you eat more” relationship existed, the opposite would be true.
But Ravussin says that correlations are always dangerous. “Let me give you one: Americans have the highest number of running shoes in the world. And they are the fattest.”
Doucet said the consensus among experts is that people who engage in 30 to 60 minutes of aerobic exercise, five times a week, can expect to lose two to three kilograms (4.5 to 6.5 pounds) after six months, “which isn’t much when you consider the efforts that go into it.”
Montreal surgeon Dr. Nicolas Christou says exercise is vital in the post-weight-loss period, that those who succeed in keeping the weight off once its lost over the long term are the ones who incorporate regular exercise into their daily lives.
But he agrees that expectations about what can be achieved via exercise need to be ratcheted down, and public policy focused more on encouraging people to eat less.
“If you run a marathon, you’ll burn about 3,000 calories. That’s a marathon, 42 kilometres. One can easily eat that in a sit-down meal in a good restaurant. Easily,” says Christou, professor of surgery at McGill University and director of the bariatric surgery program at the McGill University Health Centre.
“Exercise has been pushed too much as a means of controlling the weight. The key is calorie reduction. Exercise is icing on the cake. Yes, you’ll feel better, you’ll get a better cardiovascular system and yes, you’ll burn a few more calories. But the only way that has been shown to really impact on the weight of an individual is calorie reduction,” Christou says.
“It’s very simple physics.”
For now, Francina Kehoe can manage three tablespoons of Cream of Wheat for breakfast. “I can eat about half a cup comfortably, if I take about 20 to 30 minutes and eat it really slow.”
Sugary or fatty foods no longer interest her, because they’re not going to give her the nutrition she needs. Moreover, the “vertical sleeve” surgery not only reduces the size of the stomach, but it also removes the gastric fundus, the section of the stomach in which ghrelin, the so-called hunger hormone, is produced. For the first timein her life, Kehoe doesn’t feel hungry.
Kehoe didn’t make the decision to have surgery lightly. “It isn’t an easy way out, it’s a forced lifestyle change that has its own set of challenges,” she says.
“But when you get to be beyond just overweight into being considered not just obese, but morbidly obese, exercise and diet don’t work.”
Fourteen days after surgery, the last of the stitches were removed from Kehoe’s stomach. “I’m already down a size,” she said that morning. As of Wednesday, she was down to 241 pounds. “It feels good.”
By Sharon Kirkey, Canwest News Service