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Revving up your metabolism

What makes you tick? Your metabolism. That’s how your body absorbs and then releases stored energy in your cells to power all the daily functions you take for granted—a beating heart, breathing, lifting groceries from the car, running for the bus.

In other words, metabolism refers to how effectively your body burns calories. And it gets praised (and blamed) as the reason why some women stay super-model thin while others just can’t seem to lose those last 10 pounds.

Staying alive

To some extent, your metabolism is beyond your control. Just as the genes you inherited from your parents influenced your height and body style, so, too, they influence your metabolism.

The thyroid plays yet another role in the way your body uses calories. Normally, this butterfly-shaped gland, located at the base of the throat, keeps the metabolism humming along at just the right speed. It secretes several vital hormones into the bloodstream that regulate everything from heartbeat to calorie burn.

But in a disorder called hypothyroidism, the gland doesn’t produce enough hormones, thereby slowing down a person’s metabolism and leading to weight gain. Conversely, a condition called hyperthyroidism speeds up the metabolism, causing weight loss. Doctors do not yet understand why the thyroid sometimes changes its hormone output. But either condition can be treated with medication.

Adjusting the burner

Genetics and thyroid function aside, your metabolic calorie-burner can be adjusted to work more efficiently. Here’s where a little education and some basic math skills come in handy. First, the knowledge:

Your body is burning calories all the time, whether you’re sleeping soundly, running five miles or “vegging” in front of the TV. That’s because your brain and vital organs are constantly using energy to perform tasks like digestion, cell repair and body temperature maintenance.

Doctors call this your basal metabolic rate, or BMR. It describes the rate at which your body burns calories while at rest. Surprisingly, at least half your calories are burned this way.

Now for the math: To determine your daily BMR, divide your weight by 2.2 (for kilograms) and multiply your height in inches by 2.54 (for centimeters). Then use the BMR formula for women:

655 + (4.35 × your weight in pounds) + (4.7 × your height in inches) – (4.7 × your age in years) = your BMR

According to the equation, a 30-year-old woman who’s 5’4" and weighs 135 pounds burns 1,396 calories a day without moving a muscle. She will burn another 10 percent of the calories she takes in each day just to digest her food. And depending on how active she is, she’ll burn between 15 percent and 40 percent of her calorie intake through exercise.

Intake vs. output

So how can you accelerate your metabolism and burn more calories? Experts advise a tried-and-true formula: calorie control coupled with physical activity, especially muscle-building exercise. Although dieting alone may help you shed excess pounds, it won’t give you the lean muscle mass needed to give your metabolism a boost.

And while any exercise helps increase your calorie burn, strength training is the gold standard for increasing metabolism. The reason? Muscles burn calories eight times faster than other tissues, even at rest. (This explains why men, who naturally have more muscle tissue, seem to have an easier time controlling weight and shedding extra pounds.)

To stoke your metabolism, try these pointers:

  • Combine fitness forces. To help reduce body fat and build muscle, begin adding more activity to your day—take the stairs at work, walk to your place of worship, cycle to the convenience store. Combine more movement with a weight-training program. You don’t need any special equipment; cans from your pantry will serve as weights until you build strength. And don’t overlook calisthenics: Abdominal crunches, push-ups, squats and leg lifts all build muscle.
  • Buy high-octane fuel. Healthier dietary choices will help fine-tune your metabolic motor. Choose foods with reduced fat and salt, and eat more fruits, vegetables, fish and poultry. Go easy on the alcohol.
  • Dismiss “amazing’’ claims. Sham health-food products claim they will help you melt away pounds for miraculous results in no time. But no credible evidence exists that they work. Save your money—and maybe even your health.