So the 25% lashing making you weigh half as much actually is just a normal physics thing, same as our world. If normally you have 100% gravity downwards and you lash so that 25% points up, now you have -25% force upwards and +75% gravitational force downward (assuming down is the positive direction here). -25% + 75% = 50% gravity downwards because the 25% up cancels an additional 25% down