The average adult human, with a typical weight of 70 kg or so, thus consumes approximately
65 kg of ATP per day, an amount nearly equal to his or her own body
weight! Fortunately, we have a highly efficient recycling system for ATP/ADP utilization.
The energy released from food is stored transiently in the form of ATP. Once
ATP energy is used and ADP and phosphate are released, our bodies recycle it to
ATP through intermediary metabolism so that it may be reused. The typical 70-kg
body contains only about 50 grams of ATP/ADP total. Therefore, each ATP molecule
in our bodies must be recycled nearly 1300 times each day! Were it not for this
fact, at current commercial prices of about $20 per gram, our ATP “habit” would cost
more than $1 million per day! In these terms, the ability of biochemistry to sustain
the marvelous activity and vigor of organisms gains our respect and fascination.