In some ways, self-experimentation has more in common with economics than with the hard sciences. Without the ability to run randomized experiments, economists are often left to exploit whatever data they can get hold of. Let's say you're an economist trying to measure the effect of imprisonment on crime rates. What you would ideally like to do is have a few randomly chosen states suddenly release 10,000 prisoners, while another few random states lock up an extra 10,000 people. In the absence of such a perfect experiment, you are forced to rely on creative proxies -- like lawsuits that charge various states with prison overcrowding, which down the road lead to essentially random releases of large numbers of prisoners. (And yes, crime in those states does rise sharply after the prisoners are released.)

What could be a more opportunistic means of generating data than exploiting your own body? Roberts started small, with his acne, then moved on to his early waking. It took him more than 10 years of experimenting, but he found that his morning insomnia could be cured if, on the previous day, he got lots of morning light, skipped breakfast and spent at least eight hours standing.

Stranger yet was the fix he discovered for lifting his mood: at least one hour each morning of TV viewing, specifically life-size talking heads -- but never such TV at night. Once he stumbled upon this solution, Roberts, like many scientists, looked back to the Stone Age for explication. Anthropological research suggests that early humans had lots of face-to-face contact every morning but precious little after dark, a pattern that Roberts's TV viewing now mimicked.

It was also the Stone Age that informed his system of weight control. Over the years, he had tried a sushi diet, a tubular-pasta diet, a five-liters-of-water-a-day diet and various others. They all proved ineffective or too hard or too boring to sustain. He had by now come to embrace the theory that our bodies are regulated by a "set point," a sort of Stone Age thermostat that sets an optimal weight for each person. This thermostat, however, works the opposite of the one in your home. When your home gets cold, the thermostat turns on the furnace. But according to Roberts's interpretation of the set-point theory, when food is scarcer, you become less hungry; and you get hungrier when there's a lot of food around.

This may sound backward, like telling your home's furnace to run only in the summer. But there is a key difference between home heat and calories: while there is no good way to store the warm air in your home for the next winter, there is a way to store today's calories for future use. It's called fat. In this regard, fat is like money: you can earn it today, put it in the bank and withdraw it later when needed.