Building on the active weight transfer idea, imagine Cas exhausted from trying to fight back against the combined food intake of THREE near half-ton appetites being split between Rachel and Oli for months now, getting fed up and deciding to take a "cheat day dinner" bringing the three to a buffet to blow off a little steam (and to satisfy the still-not-adjusted hunger his body is feeling).
I imagine all three try to talk it out a bit only ordering small plates before each eating way more than they intended to walking in those doors. Sure enough the next day Cas can see the damage done, but at least it was therapeutic for the group... Not like they'd be repeating a binge like that anytime soon, right?