Calculator FAQ

In order to help you define your calorie needs, we have set up a calculator. You will find here the answers to the most common questions.

  • Why do I need to calculate my calorie needs?

Calculating your needs allows you to have an estimation of the energy that your body uses to function properly. Why does that matter? Because your body doesn't function like your neighbors', colleague's, friends' or even family's. Your needs are based on your gender, age, weight, activity level and goal. This is not something that you can just copy on someone else! 

Finding the amount of calories that your body needs will therefore help you to build your diet accordingly, and hence efficiently achieve your goal.

  • How are my calorie needs calculated?

Several steps are needed to calculate your calorie needs:

1st step, we determine your basal metabolic rate (BMR)

2nd, we multiply it by your activity factor

3rd, we adapt the result to your goal: maintain/ lose/ gain weight

We make it super easy for you! You just have to enter a few data about you and you get your results in 1 clic!

  • What is a Basal Metabolic Rate? How is it calculated?

The Basal Metabolic Rate (BMR) is the amount of calories your body spends when you are doing absolutely nothing - lying in a bed the whole day. It just the energy needed for your organs to work and your body temperature to be maintained.

Science and clinical studies have been working on finding the best way to predict someone's calorie needs as accurately as possible. Throughout the years, several equations have been established to predict the BMR, based on data from patients in clinical studies and mathematical models.

The first one, called Harris-Benedict, dates back to 1919 - and believe it or not, its revised version is still in use today . Then, the equations the most used by the online calculator nowadays, are from Schofield and Mifflin St Jeor2, introduced respectively in 1985 and 1990.

The NXT Level team of experts has gone through several scientific publications, and has decided to use the most modern equation to date: the Oxford equation introduced in 2005. This equation is more representative to the modern population and takes into account several ethnicity 1. However, keep in mind that the result that you get is an estimate.

The parameters needed by this equation to calculate your BMR are you gender, age, height and weight.

  • What is the activity factor? How do I identify my activity level?

The more you exercise, the more energy your body will need/ use. In order to quantify the amount of exercise that you get, several levels have been defined. Here is a short description of every level, so try to identify the one that matches your situation:

Sedentary: you have a desk job or are sitting most of the day. You move just to do your daily activities (dressing, housework, ...), walk to and from the car and don't exercise.

Lightly active: you have a desk job or are sitting most of the day. Besides your daily activities (dressing, housework), you try to walk a bit every day or lightly exercise (not at a point to be out of breath) 1 to 3 times per week.

Moderately active: two scenarios here

1) you have a desk job/ are sitting most of the day and besides your daily activities, you have a physical activity 3-5 times a week: dancing, biking (leisure), golfing, yoga, long walks,...

2) you are walking or standing most of the day for your job, and besides your daily activities, you have a light physical activity

Active: you either have a physically demanding job (construction work...) or are vigorously exercising 5-6 times a week: heavy workouts at the gym, running, swimming, soccer, basketball, cross fit...  

Very active: you have a very physically demanding job AND you vigorously exercise most days of the week or train twice a day.

  • What are macronutrients? And which role do they play in helping me reaching my goal?

Carbohydrates (carbs), fat and protein are macronutrients. They supply the body with the energy (calories) it needs to perform throughout the day but also ensure a large range of essential functions. Carbs are energy providers, fat protects vital organs and protein i.e. supports the maintenance and growth of muscle mass.

1g of carbs = 4kcal                1g of fat = 9kcal         1g of protein = 4kcal

The energy (from food, and hence from the different macronutrients) is either used or stored when consumed in excess. In order to reach your sports goal, it is therefore essential to make sure that the calories you provide to your body match its needs (slight deficit for weight loss, slight surplus for muscle growth, or maintenance for overall wellbeing).

Adapting your macronutrients ratio (the proportion of carbs/ fat/ protein in your diet) to your goal (gain, lose or maintain weight) and activity level, allows you to make sure that you reach your calorie intake efficiently, by optimizing the function and quantities of each macronutrient.

Quick example to illustrate: to build a house, you need different types of materials: building blocks (protein), concrete (carbs), metal (fat)… When you are planning to build a house and buy the materials, you not only need to buy all the different materials, but you also have to keep an eye on the quantities and proportions of each of them. For instance, if you have only building blocks, but nothing to attach them together, your house won’t be super strong. If you have only concrete but no structure components, your house might look a bit… flat!

  • How does the macronutrients calculator works?

The calculator is really set up on your needs.

First of all, the calculator uses the data you’ve shared to calculate your protein intake. According to the European regulation, a sedentary person needs 0,83g of protein per kg of body weight per day. Then, depending on your goal, the higher your activity level, the higher your protein intake. A very active person who wants to build muscle mass will need 1.8-2.0g of protein per kg of body weight per day.

Then we have set up the fat intake to fit in a range going from 20% of the total calorie intake for weight maintenance to 30% for muscle growth.

To finish, your carbs ratio represents the rest of the total calorie intake.

  • If I am pregnant, breastfeeding, under 18 or have any specific health condition, can I use the calculator?

And the answer is no. If you are in any of the situations above mentioned, we highly recommend that you refer to a general practitioner or doctor for nutritional advice.

If you want to know more about calories, their use by the body, and further topics linked to weight loss, feel free to check our nutrition blog.


1. Basal metabolic rate studies in humans: measurement and development of new equations.

2. A new predictive equation for resting energy expenditure in healthy individuals.