Your metabolism refers to the energy it takes to keep the countless chemical processes going inside your body to keep you alive. Energy is just another word for calories; you must consume enough calories to sustain your BMR or basal metabolic rate. If you don't consume enough calories, your metabolism slows down to conserve energy -- a survival mechanism.
Your metabolism can be broken down into three areas -- your BMR, which accounts for between 50 and 80 percent of the calories you burn; your movement which can use up to 20 percent of your energy; and digestion, which uses about 5 to 10 percent of your energy. According to the Harvard Medical School, women need at least 1,200 calories and men need at least 1,500 calories daily for optimum metabolic function. When you don't eat enough to maintain your metabolism, it slows down and you burn fewer calories. Burning fewer calories can stall your weight loss efforts.
Calories and Weight Loss
Your body is equipped with a number of survival mechanisms, some of which may be outdated. In times of famine or when food was scare, your metabolism would slow down to allow you to survive on fewer calories. In modern times, most people are not in danger of not being able to get enough calories. In fact, the majority of Americans are overweight and trying to cut calories to lose weight. To lose weight, you need to create a calorie deficit; you need to cut 3,500 calories from your current diet to lose 1 lb. You can eat less or burn more calories through physical activity. Ideally, do a combination of both -- creating a calorie deficit of between 500 and 1,00 calories daily, which will result in a weight loss of 1 to 2 lbs. per week.
Keeping Your Metabolism High
It's natural for your metabolism to slow as you age. Lean muscle tissue uses more calories at rest and it's common to lose muscle mass as you age. To keep your metabolism up, eat enough calories and ensure your body gets all the nutrients it needs. Exercise more -- any movement will use more energy; even fidgeting rather than sitting still will help burn more calories. Strength training exercises that build muscle are especially beneficial. Have your thyroid tested. Your thyroid helps set your metabolic rate -- if you have hypothyroidism, fixing your hormone imbalance will help speed up your metabolism.
The Dangers of Slowing Your Metabolism
When you're trying to lose weight, you want those extra pounds to come off as quickly as possible. You may be tempted to cut calories too much, which will slow your metabolism and stop your weight loss -- causing a plateau. Many dieters get frustrated at their lack of progress and stop dieting. Because your metabolism is slower, if you go back to your previous way of eating you will gain weight faster than you did before. You might gain back all the wight you lost, and then some!