When our bodies extract energy from food and convert it to a form that our cells can use, how much total food energy is lost as heat?
a. 75 percent
b. less than 10 percent
c. more than 50 percent
d. 20 percent

This is first hand knowledge, top-level athletes, successful business people and achievers in all fields all  set goals. setting  goals  gives you long-term vision and short-term motivation . it focuses your acquisition of knowledge, and you to organize your time and your resources so that you can make the very most of your life.

More than half is the answer

Another thing about this and it's a verified answer (on the link) i hope that !