GCCs are mainly fruit eaters in the wild so high protein is a no-no for them - thus, animal protein is real bad.
I don't give my birds any human food except a bit of multi-grain bread -and this is mainly because Zoey and Sweetpea have their one-on-one time with me while I have breakfast and Sweetpea is a royal pain in the neck about getting some -he is relentless about it and drives me crazy until I give him a tiny corner of my toast. The reason for this is that I simply do not eat healthy enough. Compared to what my birds eat, my husband and I eat crap! Most of the 'healthy' things I eat are bought for the birds so they share them with me, not the other way around

The lettuce in your hamburger is not only iceberg, which is not really recommended for birds (I can't eat it, myself) but could also have cheese, ketchup and 'the special sauce' on it.
What you can do is have always something healthy for him that you can give him instead of what you eat... like a piece of a multigrain slice of toast, air popped popcorn (never the one that you put in the microwave because even the plain one has all kinds of garbage in it), a slice of almond, a slice of apple, etc.