The present invention relates to a method and apparatus for estimating the energy consumption of a person on the basis of heart rate data. In the method, the beat rate of heart is measured with a sensor or previously measured heart rate data are input for providing heart rate data and the energy consumption of a person is determined on the basis of heart rate data. According to the invention, a first threshold value is selected for the mass of the person and in case the mass of the person is larger than the first threshold value, energy consumption is calculated using a formula taking into account the deviation of the person's mass from the said first threshold value. The invention allows getting more accurate energy consumption estimates especially for overweight persons.
