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Factors That Influence Daily Calorie Needs

Written by Barbara Bushman, Ph.D., FACSM

Food is fuel, and it takes a lot of food to fuel Olympic-level training and competition. Knowing how much food is needed is important for both Olympians and recreational athletes. 

What factors influence daily energy needs? Total energy expenditure includes:

  1. Basal metabolic rate. This reflects the energy the body needs for basic functions while at rest. 
  2. Dietary-induced thermogenesis, or the thermic effect of food. This is the energy the body needs to digest and absorb food. 
  3. The thermic effect of activity. This is the most variable as it reflects the energy needed for physical activity.  For sedentary individuals this could be as low as 15% of total energy expenditure but for athletes it could be as high as 80%.  
To determine the number of kilocalories required for training activities, researchers have determined MET values. A MET (metabolic equivalent) reflects the energy expended by the body at rest. MET values for various physical activities reflect the ratio of energy expended during that particular activity to the energy expended for an equal time at rest. For example, running at 10 mph (6 min/mile pace) is equal to 14.5 METs (i.e. 14.5 times more energy is required to run that pace than at rest).

To determine the kilocalories (kcal) burned when exercising at that level, the following calculation can be used: ____ MET value of the activity x 3.5 x ____ kg body weight ÷200 = _____ kcal burned per minute.

Thus, running at 10 mph for a 150 pound (68 kg) person would require approximately 17.3 kcal per minute; for a 45 minute training run, this would require 776 kcal. Of course, this is on top of other activity as well as basal metabolic rate and dietary-induced thermogenesis.

MET values for a wide variety of activities are available on-line (see https://sites.google.com/site/compendiumofphysicalactivities/) so individuals can determine estimated energy requirements based on specific MET values and body weight.

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Resources
  • Ainsworth BE, Haskell WL, Herrmann SD, Meckes N, Bassett Jr DR, Tudor-Locke C, Greer JL, Vezina J, Whitt-Glover MC, Leon AS. The Compendium of Physical Activities Tracking Guide. Healthy Lifestyles Research Center, College of Nursing & Health Innovation, Arizona State University. Retrieved [2011 August 22] from the World Wide Web, https://sites.google.com/site/compendiumofphysicalactivities/
  • American College of Sports Medicine.  ACSM’s Complete Guide to Fitness & Health. Human Kinetics: Champaign IL, 2011.
  • Bushman BA.  Wouldn’t you like to know: How can I use METs to quantify the amount of aerobic exercise?  ACSM’s Health & Fitness Journal. 2012; 16(2):5-7.

Barbara Bushman, Ph.D., FACSM, is a professor at Missouri State University. Dr. Bushman has authored papers related to menopause, factors influencing exercise participation, and deep water run training. She authored ACSM’s Action Plan for Menopause (Human Kinetics, 2005), edited ACSM’s Complete Guide to Fitness & Health (Human Kinetics, 2011), and serves as an associate editor for ACSM’s Health & Fitness Journal

Note: The views expressed in ACSM Olympics Hot Topics are those of the contributors only, and should not be construed as official statements of the American College of Sports Medicine.

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