Standing in a dark conference room at the Salk Institute for Biological Studies in La Jolla, California, Satchidananda Panda, Ph.D., is at the epicenter of a research movement that has rocked conventional weight-loss thinking to its core. Gesturing toward a big-screen display, Panda clicks over to a pair of maps. The one on the left shows the varying degrees of darkness and light pollution in the night sky over the continental United States. The one on the right: diabetes incidence, county by county, in the U.S. population. The charts have been adjusted to control for the greater population numbers in city areas, but still, the two are mirror images of each other.
"Where there are more lights," he says, "there is more diabetes." Those aren't refrigerator lights depicted on the night map, but they might as well be, given the effect on all of us.
Panda goes on to explain what may be happening: "My hypothesis is that staying up and eating late may be the cause. [Early on] we didn't know how to use fire. In the daytime, human beings would hunt something, eat something; but in the nighttime they had to protect themselves against predators. It was only about 200,000 years ago that we learned how to control fire, and only a few people could use fire to stay up past sunset. For the past 50 years or so we've been staying awake late into the night. That's when we see the rise of weight problems."
He has a theory about the mechanism behind it: The advent of artificial light has also led to an artificial extension of our feeding times. Our circadian rhythms have a natural stop sign built into them, and we run into that sign almost every day. Think about how you regularly sidle up to a bowl of ice cream while watching Leno, or stop at Wendy's for a late-night drive-thru snack. Modern technology has created an artificial daytime for us, and we're filling it up with meal four, meal five, and meal six. That extended eating interval throws our digestive system off-kilter and messes with the many hormones and enzymes that manage it. Our bodies can't process the food we eat, and those calories end up where they shouldn't—around our bellies and butts.
Not convinced yet? Hang in there.
Panda's laboratory devised an ingenious study to test his ideas on mice. The mice were divided into two groups and put on the same high-calorie, high-fat diet: One group was given the freedom to eat anything at any time of day. The other mice could eat as much as they wanted but only within an 8-hour time frame. The study went on for 100 days. Guess which group was plumped up?
"Simply limiting food intake to 8 hours gives you all the benefits—without having to worry about food intake," Panda explains.
For years we've been told, "You are what you eat." Turns out, we are when we eat too. (Pick up The 8-Hour Diet to learn how you can lose 20 pounds or more with this revolutionary approach.)
BEAT THE FLAB
What Panda and his voluptuous vermin are discovering isn't entirely new. For several years, researchers have also seen remarkable weight-loss results in people using a technique known as "intermittent fasting."
Don't let that f-word scare you. In this case, fasting isn't about denying yourself anything. Instead it's about simply eating what you want but staying within a sensible 8-hour window.
The fact is, you're already fasting on a daily basis. Think for a moment about the word "breakfast." It is exactly the sum of its parts—the point of the day at which you break the fast you started whenever you stopped eating the night before. In the simplest terms, the 8-Hour Diet is a way of extending the period between your last snack and your "break fast," giving your body the chance to burn away your fat stores for the energy it needs.
And burn them it does. Consider this 2007 American Journal of Clinical Nutrition study: Researchers divided study participants into two groups and had each group eat the same number of calories—enough for them to maintain their weight. The only difference: One group ate all their calories in three meals spread throughout the day, while the other practiced intermittent fasting, eating the same number of calories but in a restricted time frame. Among the results: Participants who ate in a smaller window of time had a "significant modification of body composition, including reductions in fat mass." (Find out how to use the findings to shed body-fat in The 8-Hour Diet, the new book from Men's Health.)