In fact you're probably pulling about four vertical Gs, which means you now weigh four times your usual weight. If you add speed and resistance to the equation, such as you dropping 100 feet at 70mph and shooting straight back up into an inverted loop, you are being subjected to a force greater than gravity.
That means if you weigh 12 stone, you weigh.
While standing motionless, you are experiencing 1G.
