Intrabody signal propagation uses human body tissue as the communication medium. Human body tissue consists of various components in aqueous medium which are electrolytic in nature. Changes in the amount of water in the body changes the volume of the body fluid which in turn alters the overall impedance of the tissues. These changes affect the signal attenuation of an electrical signal passing through those tissues. We investigate the effect of body fluid changes on intrabody signal propagating between 900 kHz and 1.5 MHz. Our empirical measurements on 6 subjects show that within the first 20 minutes after intake of 600 ml of water, a propagating galvanic coupled signal would have maximum rate of signal gain occurring between 900 kHZ and 1.1 MHz. Understanding that rate at which the signal changes dues to changes in body fluid level can be used for investigating human body hydration patterns with potential application in diagnosing or monitoring body fluid disorder and diseases associated with loss or rapid gain of body fluid.