AMP-activated protein kinase (AMPK) is a critical enzyme in every mammalian cell. It’s activated during “good” stress, called hormesis, like exercising, fasting, or engaging in caloric restriction. These enzymes sense low levels of energy in the body. Just as your car runs on gasoline, your cells run on ATP (adenosine triphosphate), your primary energy source. ATP molecules give away one or two phosphate molecules to fuel your cells. That turns the ATP molecule into ADP or AMP (adenosine di- or