Dieting? Get to know all about your ‘burn rate’
Laurie Sears has done it all, from calorie-counting to fad diets to Weight Watchers. But this time the Denver, Colo. resident says she’s going to succeed, and she’s willing to share her secret: She’s going to know her burn rate. “I’m about to turn 50, and I’m going to go into it healthy,” Sears said.
Few deny the importance of metabolism – or how quickly the body burns calories – in weight loss. And understanding how metabolism works can mean the difference between success and failure for the millions of Americans getting ready to start weight-loss plans, some experts say.
“It’s enormously important,” said Matt Hickey, an associate professor of health and exercise science at Colorado State University in Denver.
The first step is knowing the number of calories you burn daily without any activity. This is your “basal metabolic rate,” or BMR.
Most people know at least one “fast burner” – someone who can single-handedly clear the party buffet table and not gain an ounce because of an unusually high BMR. That person might have a BMR of 3,500, compared with a buddy whose rate is 1,500.
For most people, BMR accounts for about 70 percent of calories burned. Movement, from talking to fidgeting to running, makes up the rest of daily calorie consumption.
To lose weight, the number of “calories in” per day must be lower than the number of “calories out.” So the answer is to take in fewer calories or burn more calories, or both.
It sounds simple, but few people know the “out” side of this energy-balance equation, said Jay Kearney, vice president of clinical affairs for HealtheTech.
The Golden, Colo.-based company makes a device called the BodyGem, a hand-held mouthpiece that measures the oxygen flow in your breath to analyze your metabolic rate. The BodyGem is being used at a few Denver-area health clubs and is awaiting Food and Drug Administration approval for use by dietitians.
Now dietitians often follow the Harris-Benedict formula, which uses weight, height and age to estimate basic metabolism. “But it can be off as much as 500 calories,” said Kearney, a former Olympic athlete. An inaccurate estimate could lead dieters to assume they’re burning more calories, sabotaging their efforts to lose weight.
An inaccurate estimate could lead dieters to assume they could eat more calories than they should, fail to lose weight and give up, he said.
A University of Pennsylvania study illustrates how BMR varies among physically similar people. The study looked at 120 overweight women who were all the same age, weight and height. Their BMRs ranged from 1,263 to 2,252, with an average of 1,778.
HealtheTech conducted its own study of 200 women, comparing the old formula against BodyGem measurements. In 50 percent of the cases, the difference was 200 calories or more, Kearney said. “That’s a couple of pounds a month.”
Hickey, the CSU professor, agrees with the BodyGem concept but said he isn’t convinced it’s the answer to the nation’s growing weight problem. The latest estimate is that 61 percent of Americans are either overweight or obese.
“I’m skeptical that giving that information to people is going to make that much of a difference. We’ve had calorie counters out for years, and they seem to have met with a striking lack of success.”
Changing behavior is the key, he said.
“The one thing we can do is go out and be active,” he said. “That’s going to change your total metabolic rate over the 24-hour period.”
Adding a run or walk to a day could bump a total metabolic rate of 2,000 up to 3,000, he said. Those who do so and keep their caloric intake below 2,000 will lose weight more efficiently than will someone who diets without exercise, he said.
Stoking the metabolic fire with exercise is even more important for dieters, because as they lose weight, their burn rate is likely to decrease. That’s because they lose lean muscle mass, a fat burner, along with fat, Hickey said.
Growing knowledge that lean muscle mass has such an effect on metabolism and weight loss has led to the booming popularity of strength training.
Brian Barkley, fitness director at Cherry Creek Athletic Club in Cherry Creek, Colo., said he recently saw a client’s base metabolic rate go from 1,080 to 1,860 after a six-week exercise and strength-training program.
Counteracting dieting’s slowing effect on metabolism with the boosting power of exercise will lessen the “plateau” effect that occurs when dieters suddenly stop seeing results, Barkley said.
Barkley, a BodyGem user, believes tracking fluctuating metabolic rates and adjusting calories accordingly is the key to success.
“Rates should be rechecked every four to six weeks,” he said, especially for someone just starting an exercise program.
Once they learn their BMR, some people find out that they’ve been cutting back caloric intake too far. Eating too few calories can lead to failure because of the body’s instinct to store fat as a hedge against starvation, Kearney said. Women are more prone to fat storage than are men, he added.
Dieters also should beware of the dangers of using stimulants to help boost metabolic rates.
“I would say the vast majority of those do not work, and some of them can be harmful,” Hickey said, referring specifically to products containing ephedra, an herb also known as majuang.
Other unhealthy ways to bump up metabolism include caffeine and nicotine, Kearney said.
And when dieters stop using stimulant-based products, the weight they lost is almost guaranteed to come back, he said.
Metabolism also drops as people age – about 3 percent a decade – so people need to adjust their “energy balance” periodically, meaning eating less or exercising more, Kearney said.
While new products can help take the guesswork out of calculating metabolic rates, people can lose weight on their own. Success, Hickey said, comes through moderate lifestyle changes. No one should ever drop his caloric intake below 1,000, and everyone should add moderate exercise, he said.
“A little bit less in, a little bit more out.”
(Contact Debra Melani of the Rocky Mountain News at http://www.rockymountainnews.com.)