Background:The energy expenditure is the amount of energy (or calories) that a person needs to carry out a physical function such as breathing, circulating blood, digesting food, or a physical movement. The method for estimating the energy cost using measurement of heart rate (HR) is the physiological cost index (PCI). Aims and Objective: The aim of this study is to measure and correlate the relationship of energy expenditure of a normal healthy individual with different body mass index (BMI) and age. Materials and Methods: A total of 115 participants (59 males and 56 females) were included in this study. Written consent form was obtained. Before exercise testing, each participant's was measured that BMI was the standard formula (kg/m