Ask the Dietitian: How Do You Combat a Slowing Metabolism?

Sidney Fry, MS, RD
by Sidney Fry, MS, RD
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Ask the Dietitian: How Do You Combat a Slowing Metabolism?

Metabolism is what influences your body’s basic resting rate energy needs. But when it comes to weight loss, the main factors for success include how many calories you consume and your physical activity levels. Even at rest, your body burns energy to maintain internal functions (i.e., blood circulation, muscle repair, cell generation and repair, balancing hormones, etc.) The number of calories your body needs to carry out these internal basic functions is your metabolism, also called your basal metabolic rate — and it’s not something you can control.

Here, a look at how the body burns energy, how metabolism changes as you age and what you can do to prevent weight gain later in life:


There are three main ways the body burns energy:

  • Basal metabolism (see above)
  • Thermic Effect of Food (energy used to break down food)
  • Energy used in physical activity

Basal metabolism accounts for about 60–80% of our ability to burn calories in a day. Energy used to breakdown food accounts for about 10%, and physical activity accounts for anywhere from 10–30% (30% being limited to extreme athletes).


While basal metabolism doesn’t slow down with age, many people become less physically active. It’s also common to lose lean muscle mass and correspondingly replace it with fat as you age. The lean muscle mass of a typical young adult makes up about 50% of total body weight, which drops to about 25% of total body weight between 75–80 years old. It takes more energy (meaning more calorie burn) to maintain muscle than it does fat. That’s because less muscle corresponds to slower metabolism.

Still, metabolism is different for every individual, and science cannot exactly explain why your best friend can eat larger portions and not gain weight while you track your meals more closely and work out daily.


While everyone is different, there are still universal tips that can help prevent weight gain and a declining metabolism as you age:

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About the Author

Sidney Fry, MS, RD
Sidney Fry, MS, RD

Sidney is a two-time James Beard Award-winning food and nutrition writer, editor and mom based out of Birmingham, Alabama. A registered dietitian with a passion for research and being proactive about health, she loves to eat, write, run and create simple, tasty meals with whole-food-based approach. Find out more from her website, Instagram or Twitter.


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