Dietary fiber intake exhibits a nonlinear, inverted U-shaped association with liver fat levels in women and other racial groups, with benefits observed only above specific intake thresholds, and no linear association is present across the entire population.

When enough dietary fiber reaches the gut, bacteria break it down into molecules that signal the liver to stop making fat and start burning it instead. This only happens when fiber intake crosses a certain level, and below that level, the liver keeps storing fat. The same process also makes the body more responsive to insulin, which further stops the liver from producing excess fat.