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) a couple of times a 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 3-4 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

Very active: besides your job (desk job or walking) and daily activities, you are vigorously exercising 5-6 times a week: heavy workouts at the gym, running, swimming, soccer, basketball, cross fit...  

Extra active: you have a very physically demanding job AND you vigorously exercise most days of the week.

  • 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.


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