I am trying to figure out my own diet plan and came up with a question I can't answer.

If an obese man and an normal range weight man were both left in a room with only water, who would live the longest?

The reason i ask is I have heard fat is stored energy but I dont believe it is usuable energy. I think the obese man would expire first because his body doesnt have all the nutrients it needs.
Any input for anyone?