Answer
Your center of mass cannot be above your toes, making balancing in this position extremely difficult.
Work Step by Step
To keep your balance, your center of mass (CM) should be located above your feet’s contact area with the ground. Typically, when you stand on your tippytoes, your CM shifts forward to be over your toes.
However, if you stand with your nose and abdomen against a door’s vertical edge and try to stand on your tippytoes, your CM is prevented from moving forward. Your weight exerts a torque on you and brings you back.
