Medications
I had that same cocktail 2 weeks ago during a routine colonoscopy. Administered through IV at 9am, procedure took about 30 min or so. After my wife drove me home pretty much slept all day and through the night. Next morning still tired and groggy but able to get around, but ate very little. At 48 hours still tired but ravenously hungry, and at 56 hours felt normal.
If he had a similar procedure and followed all the orders, it's very possible he hadn't eaten much in 3 days, and had been "fully cleansed" as the doctors are fond of saying.