A method for operating an ohmic heater for heating a food product, comprising the steps of: - rectifying an alternating supply voltage by means of a rectifier ; - regulating the closing time of switches being part of an inverter generating a wave (Y) of alternating voltage that determines the passage of an electric current between a pair of electrodes located downstream of the inverter , the passage of current between the pair of electrodes causing the passage of current in the product interposed between them, causing its heating by the Joule effect; and - varying the amplitude of the wave (Y) by means of a transformer located downstream of the inverter and upstream of the pair of electrodes; determining the continuous component of the electric current entering the transformer ; the step of regulating the closing time of the switches being part of the inverter taking place as a function of the continuous component of the electric current entering the transformer so as to suppress/reduce such continuous component with a step of suppressing/reducing the continuous component; the step of suppressing/reducing the continuous component comprises regulating the closing time of the switches in order to vary the width of a plurality of positive pulses or alternatively of a plurality of negative pulses of said wave (Y) of alternating voltage; wherein the average value of the wave (Y) changes: i) by modifying the width of the positive pulses, without also modifying the width of the negative pulses; or ii) by modifying the width of the negative pulses, without also modifying the width of the positive pulses. - rectifying an alternating supply voltage by means of a rectifier ; - regulating the closing time of switches being part of an inverter generating a wave (Y) of alternating voltage that determines the passage of an electric current between a pair of electrodes located downstream of the inverter , the passage of current between the pair of electrodes causing the passage of current in the product interposed between them, causing its heating by the Joule effect; and - varying the amplitude of the wave (Y) by means of a transformer located downstream of the inverter and upstream of the pair of electrodes; determining the continuous component of the electric current entering the transformer ; the step of regulating the closing time of the switches being part of the inverter taking place as a function of the continuous component of the electric current entering the transformer so as to suppress/reduce such continuous component with a step of suppressing/reducing the continuous component; the step of suppressing/reducing the continuous component comprises regulating the closing time of the switches in order to vary the width of a plurality of positive pulses or alternatively of a plurality of negative pulses of said wave (Y) of alternating voltage; wherein the average value of the wave (Y) changes: i) by modifying the width of the positive pulses, without also modifying the width of the negative pulses; or ii) by modifying the width of the negative pulses, without also modifying the width of the positive pulses. i) by modifying the width of the positive pulses, without also modifying the width of the negative pulses; or ii) by modifying the width of the negative pulses, without also modifying the width of the positive pulses. <EOS>