I wouldn't call it a simple hack, not as easy as a pill or athletic tape.  But I benefit from that and I concur.   If you are going for more than 1 day I would use a protein drink and weight training  (including hill climbing) to avoid muscle loss... so not a strict fast for too long.   Even if you have tons of body fat, you burn both fat and muscle during a fast once you deplete your glycogen which happens in about a day.