DETERMINING CALORIE NEEDS


Let’s talk calorie needs!


How much fuel or calories from food your body needs depends on:

  • Age

  • Sex

  • Height

  • Weight

  • Training intensity

  • Activity level

  • Competition level

  • Lifestyle

  • Weather

  • Body composition goals

...and so much more.


With so much variance in individual needs, hopefully it starts to make sense why following a cookie cutter plan off the internet, the doesn't take into consideration your unique needs, is the absolute wrong choice for an athlete (or really any human).


When I’m working with athletes and determining their calorie needs, first we calculate out Resting Metabolic Rate (RMR) - this is the number of calories your body needs while completely at rest to function properly. These calories supply energy to all the many functions your body needs to keep you alive and well.


Male RMR Calculation: 10 × weight (kg) + 6.25 × height (cm) – 5 × age (years) + 5

Female RMR Calculation: 10 × weight (kg) + 6.25 × height (cm) – 5 × age (years) – 161


For most athletes, your RMR alone exceeds 1,200 calories…and remember, these are calorie needs BEFORE activity.


For an athlete training hard, 6-7 days a week, these RMR calorie needs are then multiplied by 1.725 (sometimes more) to provide adequate energy to fuel your body + training demands.

Activity Factors

Here’s an example calculation:

RMR for an 18-year-old, 135 lb, 5’5” female athlete - 1,439 calories/day


1,439 calories x 1.725 = 2,482 calories!


So a female athlete, training 6-7 days a week would need around 2,482 calories daily to fuel optimally. That’s DOUBLE these 1,200 calorie meal plans floating around. Even if you’re working on weight loss, there is absolutely no need to ever drop calories this low and doing so means your body isn’t getting enough fuel to function.


What does this mean over time? In short…your body can start eating (catabolizing) itself! If you don’t provide your body with enough calories (and carbs/protein), it will use up your stored energy (glycogen), convert fat to fuel, and also start breaking down muscle mass and tissues to supply the body with the energy it needs.


As an athlete, this is a recipe for disaster. Decreased muscle mass. Low blood sugar. Reduced energy. Loss of bone mass. Increased injury risk. Anxiety/depression. Decreased coordination and concentration. Yuck!


Bottomline: An athlete aiming to perform their best, needs to fuel their best first.

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© 2020 by Jessica Isaacs, RD