We study the magnetization exchange mechanism in lipid systems, with relevance to imaging myelin via MT contrast. Studies of samples with different lipid compositions reveal exchange time scales, and the role of structural features in the contrast mechanism. Insights from molecular dynamics provide estimates of the contribution of the dipolar pool equilibration to the MT amplitude. The effect of lipid head groups, and the contribution of cholesterol and proteins are examined. It is hoped that these findings will help explaining the origin of White Matter MT contrast and will allow better myelin quantification by tailored saturation sequences.