Because it'll make the food slide thru the stomach faster which will make it so you eat more and you won't get full as fast as you would without drinking.

:-)

If you drink beforehand, it takes up space in your stomach so you can't eat as much. If you drink during or right after it'll help wash the food out of your stomach so you're not "full" as long and will tend to eat more often....that is if you're hungry at all. I'm never hungry anyway, so I don't have to worry about that.... yet.

I wondered the same thing, and when I first got the sleeve, i thought, I'll drink when I eat, that's dumb! I tried it, and every now and then out of habit I will grab a drink by accident. For me, it HURTS! I feel like i'm going to choke or vomit when I do. It fills every last crevice in your stomach and it takes a good 30-45 minutes for the pressure to go away. Sometimes I can manage to burp and feel some relief, but it's loud and sounds and feels gross. I do find that I can drink about an hour after a meal without any pain or pressure, but everyone is different. It would be nice to drink during a meal, but for me, anything more than to wet my mouth is unpleasant.