Fructose is distinct from other foods in that it activates the fat switch that preferentially shunts the food we eat into fat. By activating the switch, obesity results from both an increase in food intake and a decrease in physical activity. The law of thermodynamics holds. However, unlike classical thinking, obesity occurring in response to fructose is not due to the animal choosing to eat too much or deciding to exercise too little. Rather, the switch is signaling the animal to eat too much and to exercise too little.
