What cause shaking of the body?

Most commonly ,in your age group, associated with stress and anxiety. If it persists see your physician. Good Luck

Presume you are asking about tremors. Common for anxiety and fear, but may see with medications, recreational drugs; a variety of disease states including hyperthyroidism, essential tremor, Wilson's disease, Multiple Sclerosis and scores of others. If your limbs shake, see your doctor.