My parrots due the same thing but the color comes back. I have been changing their diet around ever couple of days. This helps their diet and keeps them from getting bored. I like to feed them shelled peas, like one each due to the mess factor, and 1/4 in thick cuts of cucumber. if 1/4 is to thick then try paper thin cuts. Mine are about the size of a baseball now and have turned into messy eating machines. Also my parrots get their full meal every 2 days. and in between they get small snacks like shrimp pellets like 2 for each one. I have also found that when i over fed them they actually turned whiter and saw that it was because they were bloated and their scales were sticking out. Keep in mind that Parrots have some internal deformities that cause them to have issues with bloating which in some cases is deadly. If you choose to feed them peas or cucumbers be aware that this is like crack for fish. they will want it all the time and mine even would not eat for three days unless it was peas.