I'd look at pastry holders or popovers based on egg. Like there are paleo pastries made with good fats and almond flour. Does he have to be zero carb or can he do roots and fruits?

I would not want to be around a kid forced to go cold turkey off starches. His body can't change in 5 minutes - I would do a taper and swap.

Slightly different answer. Can he be part of the makeover, and together you compile a master food list?

you can go through tons of magazines and get pictures of proteins, veggies, starches and fruit that are acceptable to you. And then you shop so his favorites are on hand.