How long can a person survive on only nutritional drink like ensure in lieu of food if you can't eat solid food?

Liquid Diet: Ensure is a complete human diet and can sustain life indefinitely if adequate amounts are consumed, retained and digested. Some patients may need additional water or variations that supply more protein or fiber. In a bedridden patient, as little as 1200 calories per day may be needed. Each patient's needs should be assessed by a dietitian or physician.