In any year the average adult in the United States will gain less than one pound per year, yet will eat almost 1,000,000 calories of food.  This means that the average individual’s caloric intake (food) equal energy expenditure to within 0.3-0.6%.  How do we unconsciously so closely match our intake and expenditure?  Over the last 25 years a number of the ways we regulate our body weight have been uncovered.  We will discuss these findings and where current research is taking us.