BIG Nutrition: The Metabolism Mystique


BIG Nutrition: The Metabolism Mystique

Tina shared with me this interesting article about a writer’s 23 hour stay in a metabolic chamber. Here are some highlights:

Metabolic Basics        

Three things go into metabolism:

  • The basal metabolism (65-80% of total calories burned) is for all body functioning while at rest.
  • The thermic effect of food is the calories (~10%) burned to digest food.
  • Physical activity accounts for 10-30% of calories burned.

Factors influencing an individual’s metabolic rate include muscle and fat mass, age, gender, and genetics.

Metabolic Myths

  • Thinner people have higher metabolism than individuals with a higher body mass index (BMI). Research seems to support that, generally, people with a higher BMI have a higher metabolism than those with a lower BMI because it is more work to move a higher BMI body. However, there are individuals where this is not true, so this continues to be studied.
  • Metabolic rate decreases as people age, but day to day, week to week, it is relatively constant. The body has an adaptive response and can adjust metabolism. Scientists are not entirely sure what situations or conditions under which metabolism may change. Further, the inevitable decline in metabolism with age may not hold up if people do more to maintain muscle mass.
  • People burn more fat if they eat a diet that is high in fat (Hi, keto diet, I’m looking at you!). Nope, this is not supported by research.
  • Crash diets can have a permanent and negative effect on metabolic rate. Okay, this is not a myth. This can happen, so please don’t do this! You need food to keep and build muscle.

Metabolic Mysteries

Science cannot yet explain why:

  • Two people with similar body composition have different metabolic rates.
  • Some people with a higher BMI develop insulin resistance and diabetes while others do not.
  • Certain ethnic groups (African Americans, South Asians) have higher risk for a higher BMI than others.

One take away from this article. This writer’s body was deemed to be in the ‘normal’ range (normal metabolic rate, normal weight), but this is not how she viewed herself. This is common in my experience. I believe that this is due to the relentless images we see in movies, magazines, and television. Stick thin and/or photoshopped bodies are put forth ‘as the norm.’ These images, though, should not necessarily be equated with health.

Happy and healthful eating,

Donna G. Pertel, MEd, RD, LDN

[email protected]