A method comprising: acquiring, in an apparatus, at least one weight value representing weight of a user; acquiring, in an apparatus, a weight development target for the user; acquiring activity measurement data representing physical activity measured from the user within an observation interval; acquiring nutrition intake information of the user within the observation interval; computing, on the basis of the at least one weight value and the weight development target, at least one activity adjustment instruction indicating required physical activity of the user; and outputting the activity adjustment instruction through an interface computing, on the basis of the at least one weight value and the weight development target, at least one nutrition intake adjustment instruction indicating required nutrition intake of the user; and outputting the nutrition intake adjustment instruction through the interface, characterized by the method further comprising as performed in the apparatus: estimating, on the basis of the at least one weight value, energy expenditure computed from the activity measurement data, and energy intake computed from the nutrition intake information, future weight development of the user; outputting data representing the future weight development through the interface; and computing the at least one activity adjustment instruction and the at least one nutrition intake adjustment instruction further based on the estimated future weight development, wherein the at least one activity adjustment instruction indicates how to change the physical activity with respect to the measured physical activity and the at least one nutrition intake adjustment instruction indicates how to change the nutrition intake with respect to the nutrition intake information of the user. acquiring, in an apparatus, at least one weight value representing weight of a user; acquiring, in an apparatus, a weight development target for the user; acquiring activity measurement data representing physical activity measured from the user within an observation interval; acquiring nutrition intake information of the user within the observation interval; computing, on the basis of the at least one weight value and the weight development target, at least one activity adjustment instruction indicating required physical activity of the user; and outputting the activity adjustment instruction through an interface computing, on the basis of the at least one weight value and the weight development target, at least one nutrition intake adjustment instruction indicating required nutrition intake of the user; and outputting the nutrition intake adjustment instruction through the interface, characterized by the method further comprising as performed in the apparatus: estimating, on the basis of the at least one weight value, energy expenditure computed from the activity measurement data, and energy intake computed from the nutrition intake information, future weight development of the user; outputting data representing the future weight development through the interface; and computing the at least one activity adjustment instruction and the at least one nutrition intake adjustment instruction further based on the estimated future weight development, wherein the at least one activity adjustment instruction indicates how to change the physical activity with respect to the measured physical activity and the at least one nutrition intake adjustment instruction indicates how to change the nutrition intake with respect to the nutrition intake information of the user. estimating, on the basis of the at least one weight value, energy expenditure computed from the activity measurement data, and energy intake computed from the nutrition intake information, future weight development of the user; outputting data representing the future weight development through the interface; and computing the at least one activity adjustment instruction and the at least one nutrition intake adjustment instruction further based on the estimated future weight development, wherein the at least one activity adjustment instruction indicates how to change the physical activity with respect to the measured physical activity and the at least one nutrition intake adjustment instruction indicates how to change the nutrition intake with respect to the nutrition intake information of the user.