Someone may have a link to a better explanation, but basically, WW
designated seven comfort zones:
Zone 1 is starving, uncomfortably hungry
Zone 2 is very hungry
Zone 6 is very full
Zone 7 is stuffed, uncomfortable, wish you hadn't eaten so much
The main idea is never let yourself get to zone 1 or zone 7. I think
2 and 6 are to be avoided, but I'm not sure about this.
Stuffing yourself to the gills is not core. Getting too hungry can
overeating, also not healthy.
If you're in zone 2, you should eat! If you're in zone 6, you should
eating, and it may already be too late - you may be heading for zone 7
if you stop eating now.
As I said, I'm sure there's a better explanation out there somewhere.