Banner Health Services  



Jacklyn Diefenbach is a registered dietitian on staff at Banner Estrella Medical Center.

Question: What exactly does our metabolism do, and what factors cause metabolism to vary from one person to the next?   

Answer: Metabolism is the body’s continuous process of converting the food and beverages we consume into the energy we need to perform our daily activities, from sleeping to breathing to working. As the body converts food to fuel, energy is delivered to and used by the body’s cells. The process of metabolism continues throughout our entire lives, from conception to death.

Our individual metabolic rates are largely determined by the number of calories our bodies need to perform basic functions. Still, there are several factors that can influence our individual metabolic rates, including: body size and/or composition, gender, and age.

It takes more calories to maintain muscle than fat, so individuals who have a more muscular body composition burn more calories and often have a higher metabolism than those who are not. Further, since males typically have a more muscular body composition than females, men have been found to burn more calories and have a higher metabolism than women.

Age also impacts metabolism. As we age, our muscle mass tends to decrease and body fat begins to make up a larger percentage of our weight. This loss of muscle and increase in fat often results in slower calorie burning and a slower metabolism.

Our metabolism is a naturally-occurring process and self-regulates to properly meet the body’s daily caloric needs. While a slow metabolism is often blamed for weight gain, this is not necessarily the case. Metabolism influences and addresses the body’s energy needs. It does not determine the number of calories we consume or the amount of physical activity we engage in. Ultimately, regardless of our metabolism, if we consume more calories than our bodies need, we can expect to gain weight. If we take in fewer calories than our bodies burn, we lose weight.

If you have any question or concerns talk to your health care provider or registered dietitian. 

Page Last Modified: 03/13/2012
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