Validation of Energy Expenditure Measures Study

The energy that the human body burns and the amount of food consumed determine a person's body weight. If food intake covers the amount of energy burned, body weight remains constant - a state known as energy balance. Achieving an energy balance is not easy in everyday life. This is reflected in the increasing number of people suffering from morbid obesity. To counteract this development, it is important to have a better understanding of how much food a person should eat. In this study, the investigators will investigate the amount of food needed to meet a person's energy needs and bring them into energy balance. Primary aims of the study are i) to technically and biologically validate two whole-room indirect calorimeters (WRICs) and ii) by using whole-room indirect calorimetry, to achieve a more accurate estimate of a person's emergy balance compared to common approximation formulas. Secondary study aims: 1. To investigate whether the transfer of a person into energy balance using WRIC has an influence on energy expenditure measures compared to the transfer into energy balance using the usual approximation formula. 2. To investigate whether the transfer of a person into energy balance using WRIC has an influence on activity-dependent energy expenditure measures compared to the transfer into energy balance using the usual approximation formula. 3. To investigate whether differences in energy expenditure during energy balance during moderate and strenuous physical activity influence food intake. 4. To investigate whether energy intake in relation to energy expenditure during energy balance is related to weight development