We know we can’t under fuel and expect to succeed. Seems simple enough – but how do we know how much we need to consume. Good old math! There are a few equations we can use to help calculate a person’s energy needs for our detail orientated people OR play it by ear and check in with your body. Everything we do expels energy from breathing, grocery shopping, making your lunch, eating your lunch, on top of all your workouts!
The math route: Thank you for math teachers everywhere! There are 2 calculations best for athletic populations; that being said they were created for the general population.
Cunningham Equation
Resting Metabolic Rate = 370 + 21.6 x (lean body mass in kg)
Harris Benedict Equation
There are two versions one for each gender.
Males: Resting Metabolic Rate = 66.5 + (13.75 x wt in kg) + (5.003 x ht in cm) – (6.775 x age in yrs)
Females: Resting Metabolic Rate = 655.1 + (9.563 x wt in kg) + (1.85 x ht in cm) – (4.676 x age in yrs)
RMR is typically about 60% an athletes Total Daily Energy Expenditure. That means, these are starting points; both equations do need to be adjusted for a person’s NEAT, TEF, and EEE.
- NEAT: Non-Exercise Activity Thermogenesis is really hard to calculate. It’s the activities of daily living, twitching, sitting, posture, etc. This is often the biggest variance for people. Moreso than the fast or slow metabolism they feel they have.
- TEF: Thermal Effect of Food which refers to the energy cost of digestion, absorption, transport, and cellular update of food. Essentially how much of the food are we using.
- EEE: Exercise Energy Expenditure will vary based on intensity, duration and they type of exercise. Are you running 5 miles of 20 miles today? Both require fueling but different amounts and types. We continue to expel energy at a higher than typical rate immediately following exercise so this would be included with EEE as well.
Disclaimer: Aiming for weight loss and proper fueling for endurance sports are two contradictory goals. Our goal on their site is to support proper fueling! A person needs at least 30kcal/kg Fat Free Mass to support reproductive function and bone health. Athletes who have been under fueling and struggling with amenorrhea will need to be at a calorie surplus to help repair the damage to reestablish a regular menstrual cycle; typically, >45kcal/kg Fat Free Mass.
