I agree, and especially if you focus on getting about 100g of protein (depending on your size/sex) during that meal, and healthy carbs (veggies etc), you're not going to have a lot of room left.

My general rule of thumb is that after I do the 100g or protein and side veggies, I let myself have anything else I can eat as a treat.

Normally though, that's not much. Sometimes a little ice cream or something if I'm not being strict and cutting.