Friday, July 1, 2011

Calculating an Athlete's Dietary Needs

An Athlete's Energy Needs
They are Just as Important as Training

OK, it is another one of those blog post that make you want to love to hate me. It is full of math and scientific evidence. In this nutritional post I, again, am representing my 'client'. All of the math and formula numbers are representative of myself. I hope that through reading this blog your will learn how to determine the best diet for yourself. 

Part I: Determining the Ideal Caloric Need Based off of Activity Level.

For this section it is helpful to determine what your daily caloric estimate is  based off of the Harris Benedict equation. There are many equations out there but this is the one that I chose to use. There are male and female equations. Feel free to use this site, to determine your numbers. Knowing your daily need is the easiest way to determine your daily fat intake. 

That is just what we are going to do now. 

I used the Harris-Benedict formula for determining my client’s basal metabolic rate and daily caloric needs based on activity level (Turocy et al., 2011). My client currently has a body fat percentage of 14.3% and this formula does not account for lean muscle mass, so it could be possible that my client may need more or less calories than what this formula can predict (Turocy et al., 2011). My client is hoping to reduce his body fat percentage in the near future. 

Harris-Benedict formula
Male basal metabolic rate = 66.5 + (13.8 x kg) + (5 x height cm) - (6.8 x age {y})
Male basal metabolic rate = 66.5 + (13.8 x 70) + (5 x 153) - (6.8 x 38)
Male basal metabolic rate = 66.5 + (966) + (765) - (258.4)
Male basal metabolic rate = 1539.1 or 1539 Kcal

From here it was important to determine my client’s activity level. My client exercises recreationally for 60 – 90 min 5 to 6 days per week or a total of ≥300 min per week. He runs, rows, or uses cardio equipment for approximately ≤40 min 3 times per week plus stretching. My client also performs resistance training in conjunction with power training (plyometrics, sprints and Tabata) plus stretching 2 times per week. He plays in the Ultimate Frisbee league once a week for about 2 hours in duration. It is estimated that he exercises each week with a moderate level of activity intensity (Turocy et al., 2011). His activity level places his activity caloric needs as an additional 70% of his basal caloric need (Turocy et al., 2011).

Activity needs = .7 x basal
Activity needs = .7 x 1539
Activity needs = 1077.3 or 1077 Kcal
Daily caloric need = basal + activity needs
Daily caloric need = 1539 + 1077
Daily caloric need = 2616 Kcal p/d

The recommended fat energy requirement for athletes is 20% to 25% of total daily caloric diet (Broad & Cox, 2008). Consuming lower than what is recommended can reduce testosterone levels in males and may also play negatively on the function of the individual’s immune system (Broad & Cox, 2008). The Acceptable Macronutrient Distribution Ranges (AMDR) for fat in the endurance athlete is set at around 10% to 25%; these percentages were defined by the Institute of Medicine (IOM) and were used to determine the best percentage for my client (Phillips, Moore, & Tang, 2007). In slight contradiction to the IOM, athletes should consume no less than 15% of their caloric intake of fat, decreasing fat below 15% can place a negative effect on performance (Turocy et al., 2011).

Based off of the purported research I have set my clients fat consumption at 20% of his daily caloric need.

Fat Kcal = .2 x 2616
Fat Kcal = 523.2 or 523 Kcal p/d
Fat grams = 523 / 9 Kcal (fat)
Fat grams = 58.1 or 58 g/d

Part II: Putting the Rest of the Macronutrients Into Place


a)  Age, weight, gender and activity level of the individual

Age: 38
Weight: 70 kg
Gender: Male
Activity level: Moderate activity level. Please refer to the second paragraph in question one for specifics of activity and determination of activity level.


b)  Grams and Calories of CHO recommended for the individual

 Carbohydrates (CHO) are considered a very important macronutrient in the diet of any athlete. The AMDR recommends that the endurance athlete’s diet should be comprised of 55% to 80% of their total daily caloric intake (Phillips et al, 2007). The amount of physical activity, sports specific training volume and the intensity of that activity are all determining factors on how much CHO an athlete should consume (Broad & Cox, 2008). It has been recommended that athletes that practice moderate to heavy endurance training receive anywhere from 7 to 12 g/kg of CHO per day (Broad & Cox, 2008). Breaking down the athlete even further into muscle fiber dominance and training style can become a greater determinant of the amount of CHO needed by an athlete (Schroeder et al, 2008). Though we are unable to determine my client's fiber type, runners or endurance athletes that train at moderate intensities and participate in both endurance and power training are recommended to consume 7 to 8 g/kg or 65% to 70% of their daily caloric need (Schroeder et al., 2008).  For most athletes, even recreational athletes, 5 to 7 g/kg is recommended  for those that participate in one hour or less of moderate training per day despite their formal training or competition level (Houtkooper, Abbot & Nimmo, 2007).

Based off of the purported literature I have set my client’s CHO consumption at 6 g/kg.

CHO grams = 6 g/kg x 70 kg
CHO grams = 420 g
CHO calories = 420 g x 4 Kcal (CHO)
CHO calories = 1680 Kcal p/d


c)  Grams and Calories of Protein recommended for the individual

Athletes generally consume larger amounts than the recommended RDA of 0.8 g/kg for sedentary individuals (Phillips et al, 2007). There have been many reported benefits associated with a higher consumption of protein by athletes. Some of these benefits include; more efficient repair of damaged proteins that might have been degraded through exercise, improved maintenance of the metabolic pathways within the body, and increase the lean mass of the athlete (Phillips et al., 2007). Various literatures recommend that athletes consume 1.2 to 1.7 g/kg of protein to meet their exercise needs (Broad & Cox, 2008). However, 1.2 to 1.4 g/kg has been the recommendation for endurance athletes by the ACSM (Phillips et al., 2007), but athletes in an established training program should do fine with a decreased rate of 1.0 to 1.2 g/kg (Houtkooper et al., 2007). There is not a set upper level limit for protein, and high doses of protein are thought to increase hydration needs, impair the functionality of the liver and kidney, decrease the body’s ability to absorb calcium, and excess protein may be stored as excess fat (Sammorone et al., 2011). Because of these purported risks, it is important that my athlete not consume large amounts of protein. The risks are small, but a large protein intake could result in a decrease of CHO intake therefore impairing athletic performance and causing fatigue (Phillips et al., 2007). The endurance athlete AMDR for protein is 10% to 20% (Phillips et al., 2007).

Based off the research I have set my client’s intake of protein at 1.2 g/kg.

Protein grams = 1.2 g/kg x 70 kg
Protein grams = 84 g/d
Protein calories = 84 g/d x 4 Kcal (protein)
Protein calories = 336 Kcal p/d


d)  Grams and Calories of Fat (lipids) recommended for the individual

The endurance athlete AMDR for fat is 10% to 25% (Phillips et al., 2007). In order for most athletes to maximize their performance and to decrease fatigue it is recommended that athletes maintain a dietary fat level above 15% of their daily caloric intake (Sammarone et al., 2011). Dietary fat intake influences intramuscular triglyceride stores which are believed to play an important role in providing energy for muscles during exercise (Broad & Cox, 2008). Also, when fat consumption is too low it can affect testosterone levels in males and compromise the immune system (Broad & Cox, 2008).

Based off the research I have set my client’s intake of fat at 20% of the dietary intake of 2616 Kcal/d as mathematically determined through the Harris-Benedict formula.

Fat Kcal = .2 x 2616
Fat Kcal = 523.2 or 523 Kcal p/d
Fat grams = 523 / 9 Kcal (fat)
Fat grams = 58.1 or 58 g/d


e)   Total Caloric intake for the individual

Add it all up: 
If you are not sure how to get the percentages here is a sample formula.

Percentage CHO = CHO kcal / Total Kcal
Percentage CHO = 1680 CHO Kcal / 2539 Total Kcal
Percentage CHO = 0.66 or 66%

Make sure that you use your new Kcal total and not your previously predicted Kcal total, so you will have to add that up first. 

Caloric Totals and Percentages
420 g
1680 Kcal
84 g
336 Kcal
58 g
523 Kcal
2539 Kcal

Though the total caloric intake is lower than my predicted daily caloric need, it is only 77 Kcal shy of the Harris-Benedict predicted 2616 Kcal/d. My diet percentages remained within the endurance athlete's recommended AMDRs: fat (10-25%), protein (10-20%) and CHO (55-80%) (Phillips et al., 2007). The macronutrient densities that are shown above should be adequate for my clients needs.


I hope you get the chance to try and predict your own dietary intake. Remember, I did all the research, so all you have to do is plug some numbers into the equations that I set for you. Make sure that this new diet you create is full of nutrient dense foods, low in saturated and trans fats, and free from too many preservatives. If you are hoping to lose weight, then plug in your new desired weight into the Harris-Benedict formula and see if you can create a diet based off of that new number.    


Broad, E. M., & Cox, G. R. (2008). What is the optimal composition of an athlete’s diet?. European Journal of Sports Medicine, 8(2), 57-65.

Houtkooper, L., Abbot, J. M., & Nimmo, M. (2007). Nutrition for throwers, jumpers, and combined event athletes. Journal of Sports Science, 25(S1), S39-S47.

Phillips, S. M., Moore, D. R., & Tang, J. E. (2007). A critical examination of dietary protein requirements, benefits, and excess. International Journal of Sports Nutrition and Exercise Metabolism, 17, S58-S26

Schroeder, S., Fischer, A., Vock, C., Boehme, M., Schmiezer, C., Doepner, M., Huelsmann, O., &Doering, F. (2008). Nutrition concepts for elite distance runners based on macronutrient and energy expenditure. Journal of Athletic Training, 43(5), 489-504.

Turocy, P. S., DePalma, B. F., Horswill, C. A., Laquale, K. M., Martin, T. J., Perry, A. C., Somova, M. J., & Utter, A. C. (2011). National athletic trainers’ association position statement: Safe weight loss and maintenance practices in sport and exercise. Journal of Athletic Training, 46(3), 322-336.

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