Not trying to prove a point, just think it's more legible when I bullet point things. Also I stated in another thread I think; I don't mean to sound like an ass. I'm just a straight shooter and call it how I see it.
Anyway, the glycemic index only comes into play under the following circumstance: You are completely fasted and eat the carb source alone with no fat/protein. If you are not fasted, it doesn't apply. If you are eating some protein/fat too, it doesn't apply. Also, you'd have to eat exactly 50g of carbohydrate from that source to get a true GI response even under those circumstances. That's why it's pretty much irrelevant.
As from where I get my information from. Have you heard of people such as: Alan Aragon, Lyle McDonald, Emma Leigh, Layne Norton, Martin Berkhan, Eric Helms.
First we'll look at pizza. Have you ever looked at the nutrient profile of pizza? What do you think is bad about it? It contains plenty of micronutrients as well as a source of carbs, fats and protein. Choose one with veggies and even more micros. Meat, cheese, bread and vegetables are micronutrient rich foods loaded with high quality protein, carbs and fat and have been consumed in large amounts by larged and ripped men for decades.
Next a burger. Beef. Whole grains bun. Condiment of choice. What is bad about that?
Your body doesn't see foods, it only sees the nutrients contained in the foods.
It is very easy to reach macros and micros while fitting some pizza or a burger in.