The invention relates to an electronic device for estimating energy consumption of a person. The electronic device uses a mathematical model based on acceleration data for estimating the person's energy consumption as a function of the actual performed activity and acceleration values. The acceleration values are converted to an estimate of energy consumption of a given activity by scaling a value of time integrated acceleration data with an activity scaling parameter. The activity scaling parameters for different activities have been determined off-line by comparing measured energy consumptions over e.g. a day with estimated energy consumptions over the same period, where the estimated values are determined using the mathematical model.