I suppose he technically could but ultimately not healthy and cause a massive loss of muscle.
This was always a suckers bet, he could have fixed this in so many ways it isn't funny. Only way anyone should have taken this bet is he maintained a weight of X with a X% margin for 1 month or no dice.
Some people can literally "gain" and then shed 25pds plus alone in a week or two to show what high sodium does. This guy will gain back near everything because he is clearly losing it the wrong way, 14 pds in a week bwahahahahaha ya keep lifting weights and losing mass my brother, so sad so sad so sad.