- With Mayo Clinic nutritionist
Katherine Zeratsky, R.D., L.D.
read biographyclose windowBiography of
Katherine Zeratsky, R.D., L.D.
Katherine Zeratsky, R.D., L.D.
As a specialty editor for the Food & Nutrition Center, Katherine Zeratsky helps you sort through the facts and figures, the fads and the hype to learn more about nutrition and diet.
A Marinette, Wis., native, she is certified in dietetics by the state of Minnesota and the American Dietetic Association. She has been with Mayo Clinic since 1999.
She is active in nutrition-related curriculum and course development in pediatrics at Mayo Clinic Rochester and nutrition education related to the physiology and recommended intakes for premature infants.
Other areas of interest include breast milk and formula safety, neonatal feeding, and nutrition for breast-feeding mothers.
She graduated from the University of Wisconsin-Madison, served a dietetic internship at the University of Iowa Hospitals and Clinics, and worked as a registered dietitian and health risk counselor at ThedaCare of Appleton, Wis., before joining the Mayo Clinic staff.
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Question
Slow metabolism: Is it to blame for weight gain?
My sister insists that she is overweight because she has a slow metabolism. Is there such a thing?
Answer
from Katherine Zeratsky, R.D., L.D.
Yes, there is such a thing as a slow metabolism. But it's rare. The bottom line is: Most overweight or obese individuals do not get that way because of a slow metabolism. They get that way because they eat too many calories and don't exercise enough.
Metabolism is the complex biochemical process by which the food you eat is converted into the energy your body needs to function. Basal metabolic rate (BMR) is the amount of calories you burn at rest.
Your body composition is one of the primary factors that determine BMR. The more lean muscle you have, the more calories you burn. This is why men — who typically have more lean muscle than women do — tend to lose weight faster and gain it more slowly. It's also why experts recommend strength training to build muscle mass. BMR is also affected by how much you exercise. All physical activity, not just strenuous activity, increases the number of calories you burn.
Only a small number of people truly have a slow metabolism — which means they burn fewer calories at rest than they should according to estimates based on their height, weight, age and sex. In fact, people who are overweight usually have an increased metabolic rate because they have more muscle as well as fat.
It's true that your metabolism slows slightly as you get older. So you may need to decrease your calorie intake or increase your physical activity as you age.
If you're concerned that you have a slow metabolism, talk to your doctor. Your doctor may recommend a test to calculate your BMR, or resting energy expenditure. Medical conditions that can decrease BMR or alter your muscle-to-fat ratio include hypothyroidism and Cushing's syndrome. A doctor can test for such conditions.
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