How to help my babies lose weight?

[chqrty]

This is on my fault in a way for not being home enough to watch what amount they've been fed by my sister. But my birds are clearly getting TUBBY and I want advice? How can I help them get to a healthy weight, and how long will it take to expect results?

Anything I should know while I research how to help them?

 

[GoldenDaysAz]

Hi there! What birds do you have and what is their current diet?