Most multiple access collision avoidance-based (MAC) protocols for WLAN systems have been using fixed transmission power and have not considered energy-saving techniques targeted on channel estimation models. In order to prolong battery life and to improve the overall throughput performance of such systems, a novel PHY-MAC cross-layer energy-saving mechanism based on a distributed queuing MAC protocol and fuzzy logic theory is introduced for WLAN systems. Computer simulations have been performed and values for the throughput maximum performance and energy consumption have been obtained as a function of different scenario parameters. These values show that the throughput outperforms the one obtained with the IEEE 802.11 standard while reducing the energy consumption.