Fitness Apps

Can I trust fitness apps?

Despite the fact that fitness gadgets can make you move more, it is important to understand that the numbers shown by such a device or application are most often very conditional and can differ from reality not just by individual percentages, but by whole orders.

Manufacturers, taking care of the visual representation of data and fashion design, often use outdated calculation methods, not to mention the fact that the logic of measuring motion in terms of heat( calorie) units has a controversial scientific base.

Basic calorie level

Any fashionable fitness tracker or advanced application for a smartphone determines the daily calorie rate of a user according to one of the classical formulas known for more than a hundred years, because there are simply no other ways to determine the figure.

However, even 50 years ago it was clear that these formulas are very approximate - the energy expenditure of two people of the same sex, age, similar constitution and lifestyle can differ by figures of the order of 30-40%.The reason is individual factors.

Calculation of calories burned

The calorie needs of a particular person vary from day to day depending on the basic metabolic processes( about 70% of all energy, a third of which is in brain work), ambient temperature and even emotional state.

Energy costs from physical activity usually make up no more than 20% of the total energy expenditure - most of it is for daily movement, not for training in the gym. By itself, sport does not burn a significant amount of calories.

How many calories does walking burn?

It is important to understand that the very idea that a certain amount of calories burned by the body is a mathematical approximation for one done step. Calorie is a measure of heat, which has a very distant relationship to the energy of motion.

The figures of calorie consumption as a result of physical activities used by fitness trackers are based on studies conducted many years ago - the figure shown may differ significantly from the amount of energy spent by your body.

What is calorie?

The physical meaning of one calorie is that it is the amount of energy required to heat 1 g of water per 1 g of Celsius at atmospheric pressure of 101.3 kPa. Caloric content of food is determined by how much heat is released when it is "burned" in a special appliance.

However, the figure indicated on the product package is nothing more than a miscalculation - the figures obtained 1 year ago are 1 g protein = 4 kcal, 1 g carbs = 4 kcal and 1 g fat = 9 kcal multiplied by the number of proteins, fats and carbohydratesin the product.

How much energy is absorbed from food?

Strictly speaking, it is not known how much the "caloric value" indicated on the product package differs from the direct amount of energy received by a particular person. However, it can be said with certainty that this value is of the order of 10-30%.

The total number of caloric values ​​of certain products( error of 10-30%) is imposed on the figure of the calorie norm, determined with an error of 30-40%, which are then shifted to an activity level based on averaged and very approximate data.

Heart rate monitor

Two years ago there were no heart rate monitors capable of measuring the heart rate solely by contact with the wrist, since it was believed that the figure would be distorted. Today, these devices began to appear - but the design has changed, but not technology.

The resulting error of the fitness bracelet or application is so great that the figure shown may not have anything to do with reality. It is important to understand that such devices still remain a toy rather than a tool for controlling health.


It is important to refer to different devices and applications for measuring physical activity level more like a beautiful virtual number, but as a real recommendation. The very approach of measuring activity by units of heat( calories) leaves a lot of questions.

Last Modified:

  • Dec. 9, 2014