Every time you eat, your body immediately begins converting that food into energy. It then allots the energy to three functions -- activity, digestion and your basal metabolic rate, or BMR. Your BMR is the calories your body requires in a resting state simply to exist. It's what people commonly refer to as metabolism, according to MayoClinic.com. Between 60 and 75 percent of the calories you need each day go toward fueling your metabolism.
High Metabolism
If you have high metabolism, your BMR might require as much as 75 percent of the calories you give your body each day. On a 2,000-calorie daily diet, this means that as many as 1,500 of those calories go to just keeping you alive. According to MayoClinic.com, your digestive system needs an additional 10 percent of your daily calories to process the food you eat, and this is not included in your BMR. On a 2,000-calorie diet, your body would need a total of 1,700 calories just for bodily functions, or 1,500 plus 200. This leaves only about 300 calories for your activity level. If you burn more than 300 calories through exercise and activity, it can result in weight loss whether you're intentionally dieting or not.
Low Metabolism
If your body uses only about 60 percent of your daily calories for your BMR, your metabolism is on the low side. You'd need only about 1,200 calories to maintain your bodily functions on a 2,000-calorie diet. If you add the additional 10 percent that your digestion requires, your body uses about 1,400 calories per day, or 1,200 plus 200, if you don't get any activity or exercise at all. You'd have to burn off the additional 600 calories you ate, the difference between 2,000 and 1,400, to avoid gaining weight. People with low metabolism usually have to exercise more or eat less to maintain their weight.
Influences on Metabolism
Susan Roberts, a professor at Tufts University and author of "The Instinct Diet," indicates that certain variables can affect your metabolism. For example, women's metabolism can increase up to 5 percent during the last part of their menstrual cycles. Men generally need about 300 more calories per day than women to maintain their basal metabolic rates. Age decreases metabolism. Roberts says that your BMR can drop up to 2 percent each decade of your lifetime.
Tips
In 2010, researchers at the Department of Medical and Health Services in Sweden studied the perception by individuals that they have either high or low metabolism. Their research determined that the BMRs of 44 participants who thought they had high metabolism were no different than the BMRs of 12 participants who thought they had low metabolism. Roberts says that few individuals have a metabolism that differs from the average by more than 10 percent.
References
- Mail Online; Can't Lose Weight? Don't Blame Your Metabolism; Dr. Susan Roberts; November 2009
- MayoClinic.com; Slow Metabolism: Is It to Blame For Your Weight Gain?; Donald Hensrud, M.D.; April 2009
- MayoClinic.com; Metabolism and Weight Loss: How You Burn Calories; October 2009
- "Scandinavian Journal of Clinical and Laboratory Investigation"; Comparison of the Subjective Sense of High or Low Metabolism and Objectively Measured Resting Metabolic Rate; A. Wallhuss, et al.; September 2010
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