A system for measuring nutritional parameters of food items is provided. The system includes a holding cavity. The system further includes a sensor assembly that includes a transmitter antenna and at least one receiver antenna. The transmitter antenna is configured to transmit signals to a food item in the holding cavity. The receiver antenna is configured to receive response signals from the food item. The system includes at least one switch coupled to each antenna. The switch, in a first state, is configured to set the sensor assembly to an electric potential equal to that of the holding cavity. In a second state, the switch is configured to couple the sensor assembly to a power source. The system also includes a processing unit to process the signals received to determine the nutritional parameters of the food item.