I think it's different for everyone. My loss of appetite is not because my band is too tight. I have no trouble eating. Yesterday for dinner I had shredded pork carnitas minus the tortilla topped with guacamole, sour cream, cheese and lettuce. I ate the equivalent of a full cup of that. And it took me about 45 min to eat it.
But, I could have just as easily not eaten anything and been fine.
This morning I ate one scrambled egg and 1/2 cup of oatmeal. But I wasn't "hungry"...
There is no one size fits all solution with the band or any other diet/weight loss efforts including what the green zone means for an individual. Eating as little as I do my labs come back good, my Vitamin levels are good and my doctor certainly doesn't call it starvation or malnutrition.