Here are all the burning facts you need to know about that mysterious calorie-burner we call metabolism.
Metabolism fuels your body using calories you've eaten.
You probably associate the word metabolism with weight gain and loss, but it's really a name for the process by which your body converts food into fuel.
Even at rest, your body needs energy — in the form of calories you've eaten — for basic functions such as circulating blood, breathing, and growing and repairing cells. Up to 75 percent of the calories you take in every day go toward this resting metabolic rate, or RMR (sometimes called basal metabolic rate, or BMR). The remainder gives you the fuel you need for daily activities and helps with digestion. (Yes, the mere act of processing foods burns calories!)
Most women need 1,200 calories a day to support their RMRs, plus 200 to 400 extra calories for daily activities (and even more if you exercise regularly). Unfortunately, whatever surplus your body can't use ends up stored as junk in your trunk (or thighs or belly).
"It's simply a matter of intake versus output," says cardiologist Joseph Klapper, M.D., author of The Complete Idiot's Guide to Metabolism.
"Consume more calories than your metabolism needs, and you'll gain weight."
