Depleting tryptophan, the precursor to serotonin, caused significant anxiety reduction in both healthy and anorexic women.
It was proposed by the authors that the depletion of tryptophan (serotonin) is why anorexics find relief from eating less.
Anorexics also had a higher level of tryptophan compared compared to the amino acids that compete for brain penetrance ('LNAAs'). This suggests that those with anorexia may have excessive serotonin production in the brain, and tryptophan restriction corrected it.