we call this "junk food night" lol yesterday was my gliders junk food night, I had also run out of staple ( made 2 batches today ) so, they had scrambled eggs, melon and mixed veg ( normal portions of each ) one of their favorite junkfood dinners. You can substitute the eggs for yogurt ( no artificial sweeteners ) or boiled chicken or turkey, mine even get baked salmon occasionally on junk food night
One night of no staple isn't going to do any kind of damage, when it's long term is when it can cause health issues