Question

What would most likely occur if the body was unable to create and use ATP immediately?

Answer 1

The cells would become energy starved leading to ischemia and then infarction. This is if one was unable to do anything else to maintain the homeostasis.

You body however is able to utilize several mechabisms, primarily the use of fats and in extreme cases muscle tissue for the use of energy and ATP production through anaerobic metabolisis.