Calculating energy needs for proper weight and body composition

Each athlete has unique energy needs and determining calorie needs is important for optimal performance and body composition.  Athletes that consume too much energy may increase body fat composition and hinder performance. In contrast, athletes that do not consume the proper energy intake are unable to meet the training demands and may decrease endurance, power and lean muscle mass. To help you determine total energy needs, Dexalytics recently added a feature to calculate energy needs for proper weight and body composition. 

While difficult to measure accurately, there are several methods for calculating total daily energy expenditure (TDEE) or energy needs for athletes. The most accurate method of determining TDEE is measuring an individual’s energy expenditure using a whole-room calorimetry chamber. These chambers are expensive and often underestimate TDEE because they limit the movements of the individual to a very small room. Similarly, stable isotopes of hydrogen or oxygen (i.e., doubly labeled water) provides another method of determining TDEE, but these isotopes are expensive and not practical for use outside of research. Therefore, TDEE in individuals is commonly determined by multiplying either the estimated or measured RMR by a given physical activity level. With a click of a button, Dexalytics calculates the proper energy needs for athletes.   

Dexalytics calculates TDEE using a formula developed by the Institute of Medicine (IOM) (Brooks et al., 2004). To use the formula the user needs to select a physical activity category.  For a sedentary person who spends his or her entire day sitting, the IOM uses a value of 1.0 for both males and females. The IOM uses a value of 1.11 for males and 1.12 for females who sit most of the day but do some walking to perform tasks of daily living. For athletes who exercise approximately an hour a day or for individuals involved in very active vocations, the IOM formula uses 1.25 for males and 1.27 for females.  For competitive athletes who engage in several hours of vigorous exercise training, the IOM formula uses a value of 1.48 for males and 1.45 for females. 

Those individuals working with highly competitive athletes may just want to use the values for a competitive athlete exclusively, however, if an athlete gets injured and cannot train at the very active level, you will select a lower physical activity level.  This will change the TDEE, which is important since many athletes who have suffered an injury continue to consume their normal level of calories and gain weight.  

For example, a 6 ft. 2 in, 250-pound linebacker who is working out several hours a day would have an average TDEE of 4,604 calories.  If his activity level drops to very low due to an injury, the TDEE drops to only 3,564 calories resulting in a decrease of approximately 1,100 calories per day. If this athlete did not adjust his energy intake by the end of one week he would have consumed an additional 7700 calories and would have a weight gain of 2.2 pounds a week. 

The value of counseling the athlete on eating wisely during an injury is important for return to play at a normal body weight. Calculating TDEE can also be used to calculate how many calories need to be consumed to either gain or lose weight. So if an athlete needs to gain weight the nutritionist or coach can tell them how many additional calories they need to consume to have a steady increase in weight or just the opposite if the athlete wishes to lose weight.
Brooks GA, Butte NF, Rand WM, Flatt JP, Caballero B. Chronicle of the Institute of Medicine physical activity recommendation: how a physical activity recommendation came to be among dietary recommendations. Am J Clin Nutr. 2004;79(5):921S-930S.


About the Author: Donald Dengel, Ph.D., is a Professor in the School of Kinesiology at the University of Minnesota and is a co-founder of Dexalytics. He serves as the Director of the Laboratory of Integrative Human Physiology, which provides clinical vascular, metabolic, exercise and body composition testing for researchers across the University of Minnesota.

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