As the cars move through the loop, the net force acting on your body is constantly changing. At the very bottom of the loop, the acceleration force is pushing you down in the same direction as gravity. Since both forces push you in the same direction, you feel especially heavy at this point.

Going through a "clothoid" loop on a roller coaster is a multisensory experience that combines the feeling of extreme heaviness with a brief moment of weightlessness. As you enter the bottom of the loop at maximum speed, you experience positive G-forces—often 3 to 4 times the force of gravity—which makes your body feel incredibly heavy, pushing you firmly into your seat and making it feel difficult to lift your arms. As the coaster climbs and begins to invert at the top of the loop, the G-forces drop significantly; for a split second, the centripetal force pushing you into the seat nearly balances the gravity pulling you out, creating a sensation of being "light as a feather" or even slightly floating. Physics-wise, the "false gravity" created by your inertia keeps you safely in the seat even while upside down. Visually, the world "flips" as the horizon disappears and the sky takes its place, often resulting in a brief moment of disorientation or "adrenaline-induced tunnel vision" before the coaster levels out and you feel the familiar "heaviness" return at the exit of the loop.