Many diseases can result in increased fatty infiltrations within muscles adjacent to lumbosacral plexus. However, the normal level of fat content in paraneural muscles is not clear within healthy people. In this study, we applied iterative decomposition of water and fat with echo asymmetry and least-squares estimation intelligent quantification (IDEAL-IQ) to measure fat fraction (FF) of paraneural muscles within healthy participants. We found that FF values of paraneural muscles in healthy people depend on gender and age. Therefore, both factors of gender and age need to be taken into account, when assessing the FF levels of muscles in diseases.