Abstract: This invention discloses a multifunctional diet calculator comprising a user operable input for receiving at least one target amount of at least one food substance to be consumed by a user and information regarding actual consumption of food substances by the user, a memory for storing target amounts of the at least one food substance and cumulative actual consumption thereof over a given period, a computation unit for determining the relationship between the target amounts and the cumulative actual consumption, an output device showing the relationship between the target amounts and the cumulative actual consumption, a prompt unit for providing at least one user sensible prompt during the given period for reminding the user to consume a food substance and a clock for providing timing information for at least the computation unit and the prompt unit.