A system for determining a water and a lipid level of skin, the system comprising: at least two electrodes suitable for contacting skin; a signal generator configured to generate an electrical signal at a frequency across the at least two electrodes; a conductivity measurement system for measuring a plurality of conductivities at a plurality of frequencies between the at least two electrodes; and a processor for processing the output of the conductivity measurement system, wherein the signal generator is configured to generate an electrical signal at a first frequency in a first frequency range and the system is configured to determine a water level of skin based on the measured conductivity when the frequency of the signal is the first frequency, wherein the first frequency range is a frequency range from 10 kHz to 100 kHz or a frequency range from 0.8 MHz to 5 MHz, wherein the first frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is lower so that the skin conductivity is less sensitive to the lipid level; and wherein the signal generator is configured to generate an electrical signal at a second frequency in a second frequency range and the system is configured to determine a lipid level of skin based on the measured conductivity when the frequency of the signal is the second frequency, wherein the second frequency range is a frequency range from 10 Hz to 500Hz or a frequency range from 10 MHz to 100 MHz, wherein the second frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is higher so that the skin conductivity is more sensitive to the lipid level; and wherein the system is configured to: when the frequencies of the generated electrical signal are in the first frequency the measured conductivity is used to determine the water level of the skin and when the frequencies of the generated electrical signal are in the second frequency range the measured conductivity is used to determine the lipid level of the skin; compare the measured conductivity to one or more predefined profiles describing the manner in which skin conductivity varies with frequency; and determine a water and a lipid level of skin based on the comparison of the measured conductivity and the frequency of the radio frequency signal. at least two electrodes suitable for contacting skin; a signal generator configured to generate an electrical signal at a frequency across the at least two electrodes; a conductivity measurement system for measuring a plurality of conductivities at a plurality of frequencies between the at least two electrodes; and a processor for processing the output of the conductivity measurement system, wherein the signal generator is configured to generate an electrical signal at a first frequency in a first frequency range and the system is configured to determine a water level of skin based on the measured conductivity when the frequency of the signal is the first frequency, wherein the first frequency range is a frequency range from 10 kHz to 100 kHz or a frequency range from 0.8 MHz to 5 MHz, wherein the first frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is lower so that the skin conductivity is less sensitive to the lipid level; and wherein the signal generator is configured to generate an electrical signal at a second frequency in a second frequency range and the system is configured to determine a lipid level of skin based on the measured conductivity when the frequency of the signal is the second frequency, wherein the second frequency range is a frequency range from 10 Hz to 500Hz or a frequency range from 10 MHz to 100 MHz, wherein the second frequency range comprises frequencies in which the contrast between the conductivities of lipids and wet or dry skin is higher so that the skin conductivity is more sensitive to the lipid level; and wherein the system is configured to: when the frequencies of the generated electrical signal are in the first frequency the measured conductivity is used to determine the water level of the skin and when the frequencies of the generated electrical signal are in the second frequency range the measured conductivity is used to determine the lipid level of the skin; compare the measured conductivity to one or more predefined profiles describing the manner in which skin conductivity varies with frequency; and determine a water and a lipid level of skin based on the comparison of the measured conductivity and the frequency of the radio frequency signal. when the frequencies of the generated electrical signal are in the first frequency the measured conductivity is used to determine the water level of the skin and when the frequencies of the generated electrical signal are in the second frequency range the measured conductivity is used to determine the lipid level of the skin; compare the measured conductivity to one or more predefined profiles describing the manner in which skin conductivity varies with frequency; and determine a water and a lipid level of skin based on the comparison of the measured conductivity and the frequency of the radio frequency signal.