Preschooler has gone to white food only: rice, curd, idli, milk

Two weeks now. Anything with colour gets pushed to the edge of the plate. Dal is allowed only if it's thin enough to pass as white. He isn't losing weight and is otherwise fine. I've read 'keep offering, no pressure' in five places. I want specifics. How long did this last for your child, and did anything shorten it?