Exercise and Metabolism: Reality Check

November 13, 2012 General Interest

Metabolism, simply defined, is the energy your body uses up to keep you alive. Our culture is kind of obsessed with speeding up metabolism. Miss Jillian is only one of many examples I could have posted here. And you want to know what’s crazy, the same culture promotes ideas that actually slow your metabolism down! Seriously.

Take the example of dieting and exercise. Turns out cutting your calories quite low and adding exercise on top of it actually slows your metabolism down. Don’t believe me? Check out these studies that illustrate this phenomenon over and over again.

Thompson et al. Effecs of Diet and Diet-Plus-Exercise Programs on Resting Metabolic Rate: A Meta-Analysis. Intl J Sport Nutr. 1996(6):41-61.Resting

 Metabolic Rate (RMR) decreases significantly when an individual participates in a diet only program….exercise…does not return RMR to baseline levels.

Gornall J and Villani. Short-Term Changes in Body Composition and Metabolism with Severe Dieting and Resitance Exercise. Intl J Sport Nutr. 1996(6):285-294.”..

4 weeks of resistance training did not prevent or reduce the decline in fat-free mass and RMR observed with very low calorie diets”

DEUTZ RC et al. Relationship between energy deficits and body composition in elite female gymnasts and runners .MEDICINE & SCIENCE IN SPORTS & EXERCISE. 2000.

Study indicates that starvation, famine, or energy restriction may cause a reduction in energy metabolic rate and a relative increase in fat storage from the limited energy consumed. 

Martin CK, et al. Effect of Calorie Restriction on Resting Metabolic Rate and Spontaneous Physical Activity OBESITY Vol. 15 No. 12 December 2007.

The results of this study indicate that Resting Metabolic Rate adapted or decreased beyond values expected from changes in weight and body composition as a result of energy deficit that was achieved through a food-based diet (25% Calorie Restriction) after 3 months and a food-based diet plus structured exercise (25% total Calorie Restriction) after 6 months. Additionally, Resting Metabolic Rate decreased beyond expected values at month 6.

Doyle-Lucas AF, Akers JD, Davy BM. (2010). Energetic efficiency, menstrual irregularity, and bone mineral density in elite professional female ballet dancers. J. Dance Med. Sci. 14(4): 146-54.

http://www.ncbi.nlm.nih.gov/pubmed/21703085

This study was conducted on 15 professional adult dancers and 15 non-dancing age matched controls. Despite having a similar fat-free mass, dancers had a significantly lower resting metabolic rate (RMR) as well as lower RMR relative to fat-free mass. Energy intake was significantly lower among dancers compared with controls and the authors conclude alterations in RMR may be an indicator or low energy availability (nothing new) and that larger scale studies are warranted to investigate this possibility.

Want to know the best way to support a health metabolism?

  • Moderate exercise
  • Eat enough to fuel yourself during the day. This means honoring, rather than ignoring your hunger.
  • Get plenty of rest
The reality is that your metabolism is largely determined by your genetics. We really can’t do much to change it. I’m sorry if this news is disappointing to you. But what you can do is seek a place of balance. Balanced eating, balanced exercise. Turns out that balance is the very best way to support a healthy metabolism. 
Isn’t it interesting that plain old good self-care also supports your healthiest metabolism? Not as glamorous as Jillian Michaels in a sports bra…but hey, the truth ain’t always sexy!