How to calculate your calories and macros!

Calculating your energy requirements is usually the first point of call for starting any sort of nutrition or performance plan. This article will break down the steps I use as a performance nutritionist to calculate energy requirements and macronutrients breakdown for my athletes.

To start with you will need to know or resting metabolic rate (RMR) or how to calculate it. Resting metabolic rate is the minimal amount of energy required to maintain basic bodily functions. The gold standard measure of RMR in in-direct calorimetry, but, without access to plenty of expensive equipment your best bet is using one of the validated equations such as the Harris-Benedict equation.

The Harris-Benedict Equation:

RMR = 66.5 + (13.75 x weight in kg) + (5.003 x height in cm) - (6.755 x age)

For example, a 60kg female, aged 40 and standing at 165cm would have an RMR of 1514 calories.

Now we need to take the energy requirement of activity from daily tasks just as steps and that of planned exercise or sport. To do this, you multiply your RMR by your Physical Activity Level (PAL).

Physical Activity Level:

Sedentary (little or no exercise) = 1.2 PAL

Lightly active (exercise 1-3 times per week) = 1.4 PAL

Moderately active (exercise 3-5 times per week) = 1.6 PAL

Very active (exercise 6-7 times per week) = 1.8 PAL

Highly active (daily, vigorous exercise) = 2.0 PAL

Our example is lightly active and therefore we would multiply her calculated RMR of 1514 by the PAL of 1.4 giving the energy requirement of 2120 calories per day to maintain BM and fuel current activity.

The final step is dependent upon individual goals. If the goal is to lose body fat, 500 calories will be subtracted from this to create a sufficient energy deficit. On the other hand, if the goal is to gain mass, a calorie surplus of around 350 will provide the conditions to best aid this goal.

Example:

Weight loss calories = 1620 (2120-500)

Mass gain calories = 2470 (2120+350)

Please note that calories should be a range with more energy being required for more active days.

Now you know your calorie targets. But what percentage of these calories should be made up from proteins, carbohydrates or fats?

Protein

To the amount of protein, you should be aiming to consume for an active lifestyle, take your bodyweight in kilograms multiply by 1.6-2.2. This will give you a target in grams. Where you fall on the scale between 1.6-2.2 will depend on how comfortable you are at consuming high amounts of protein and how advanced at resistance training and muscle mass you have.

Carbohydrates

Amount of carbohydrates will depend on your activity levels. Most people will require 3-5g of carbohydrate per kg of bodyweight with 5-7g/kg/BM for more active individuals and 7-10g+/kg/BM for highly active individuals competing in marathons, triathlons and ultras.

Fats

Dietary fat should make up 25-30% of total energy intake. To calculate this, take your calorie goal and multiply by either 0.25 or 0.3, divide the answer by 9 to know how many grams of dietary fat you should be aiming to consume.

These are the calculations and decisions that performance nutritionists go through to ensure you are fuelling your performance and health.