You Are Stranded on an Island with No Way to Communicate

You are stranded on an island with no way to communicate or signal for help.Your only hope is that somebody has tracked your last known location and will begin a search from there.Nevertheless, it will be a while before you have a chance of seeing another person.You have found a fresh stream of water at the center of the island, but other than green leafy plants, food options appear nonexistent.
A.What substances are used as energy stores within your body? In which organs?
B.Which will be used first in the absence of ingesting external sources of energy? How long will this source last?
C.What other substance will your body then turn to? On average, how long before you run out of that fuel source? Explain why this second fuel source is a better choice than the first-used source as your long-term energy store.
D.What enzyme is required for the breakdown and usage of the energy source you listed in part B? If you are a person with a deficiency in that enzyme, how does this affect your other estimates?