The second group of volunteers (60) follow the protocol of doubly labeled water to evaluate their energy expenditure during 10 days in free living conditions. For this period, their heart rate, parameters of actimetry and other parameters are recorded . The participants of this second group also answer the questionnaires of perception of hunger, emotional state and visual appreciation of 6 food products, over one day at home. The physical data recorded on this second group will be introduced into the predictive equations. The estimated energy expenditure will be compared with the energy expenditure measured by the technique of doubly labeled water. The answers to the questionnaires filled out by the volunteers of the two groups will be also compared.