It seems so simple: Calories in, calories out. Burn more of them than you take in, and you shed pounds; consume more than you burn, and you put on weight. How, then, can something so straightforward be so vexing?
It seems so simple: Calories in, calories out.
Burn more of them than you take in, and you shed pounds; consume more than you burn, and you put on weight.
How, then, can something so straightforward be so vexing?
The frustration doesn’t stem solely from a lack of willpower to eat right, limit portions and make time for that morning run. One reason is our metabolism, the means by which our bodies convert food and drink into energy.
There’s no doubt that diet and exercise are the major forces at work when we step on the scale, but experts say metabolism also has an interrelated and important role.
“The body’s metabolic rates play some role in the regulation of body fat and lean mass, primarily muscle mass,” said Dr. Andrew Greenberg, the director of the Obesity Metabolism Laboratory at the U.S. Department of Agriculture’s Human Nutrition Research Center on Aging, located at Tufts University near Boston.
Sometimes our metabolism conspires against us. When we work to create a caloric imbalance — more energy going out than coming in — we might see a desired weight drop at first. But then our bodies seek to correct the imbalance. Our metabolism slows, and the weight loss stalls.
Aging also places a drag on our metabolism. After age 30, people who are inactive can lose as much as 5 percent of their muscle mass per decade, according to WebMD. That has implications for how many calories we burn at rest.
“Muscle is the major energy burner in the body,” said Dr. John Kirwan, the director of the Lerner Research Institute’s Metabolic Translational Research Center at the Cleveland Clinic.
Each pound of muscle burns six calories per day, compared with just two calories per day for fat, said Dr. David Bradley, an endocrinologist at Ohio State University’s Wexner Medical Center.
Exercise, particularly resistance training such as weightlifting, can help counteract the metabolic slowdown by increasing the body’s proportion of muscle and, hence, its resting metabolic rate. It also helps ensure that the weight we lose is made up of more fat than muscle.
Getting a good night’s sleep also has been shown to play a role in our metabolic rate. People who are sleep-deprived tend to have higher levels of
hormones that promote not only eating but also the depositing of fat, Greenberg said.
Opting for smaller, more-frequent meals also can make a difference because your metabolic rate increases when you eat, Kirwan said. And such a practice might help you feel full, reducing the risk of overeating.
A high-protein diet also can give your metabolic rate a small boost. So can caffeine, but experts say the metabolic benefit is minimal and doesn’t justify the risks and drawbacks.
Recent research by the Cleveland Clinic has found some evidence that whole-grain diets are beneficial for people trying to lose weight. A randomized, controlled trial found that whole grains can affect glucose metabolism and caused a single-digit percentage increase in the body’s rate of oxidizing fat, Kirwan said.
Intestinal bacteria — often dubbed the “microbiome” — regulate metabolic function and energy balance, but much has yet to be learned about their role in regulating our metabolism, Greenberg said.
Experts say there are plenty of myths and misinformation circulating about metabolism.
One is that people who are overweight or obese have lower metabolic rates. In fact, Bradley said, people who weigh more tend to have higher metabolic rates when at rest. If they lose weight, however, their metabolic rates probably will slow.
As a result, someone who goes from 300 pounds to 200 pounds can have a lower metabolic rate than a person who never weighed more than 200 pounds. That often makes it more difficult for the person who lost weight to keep it off.
People should have realistic expectations for their metabolism. Willpower might help a person adjust their metabolism in the short term, and, in unusual cases, some people are able to establish a new balancing point between “energy in” and “energy out,” Kirwan said.
But, he added, “for the most part, your set point for your metabolic rate is predetermined.”