You Are When You Eat
1 Jackie Rodriguez gained 70 pounds after her first child was born. Then, when her daughter was two, she dropped all the weight with practically no effort. The transformation had nothing to do with what Rodriguez ate. Her main adjustment was moving dinnertime almost four hours earlier. That single, simple change seems to have triggered Rodriguez's dramatic weight loss—and emerging scientific evidence may explain why.
2 In labs around the world, researchers are developing a completely new understanding of how metabolism works. It seems that our bodies process food most efficiently when it's eaten during daylight hours. "We now recognize that our biology responds differently to calories consumed at different times of day," says Harvard neuroscientist Frank Scheer, Ph.D. That means a habit as harmless as eating at night, compared with eating calorically equivalent meals during the day, may cause people to gain weight.
3 Just look at Satchidananda Panda's mice. A molecular biologist at the Salk Institute for Biological Studies in California, Panda is a leading expert on how the timing of food intake affects health. His team has found that mice that eat only during their active hours (the equivalent of daytime for humans) are drastically healthier and thinner than mice that eat the same amount of food scattered over 24 hours.
4 Encouragingly, when unhealthy, snack-around-the-clock mice are put on a strict schedule that allows them to eat only during their daytime, their diabetes and fatty liver disease improve and their cholesterol levels and inflammation markers diminish. "It's likely we can reduce the severity (of disease) just by changing when people eat," Panda says.
5 To understand the connection between meal timing and health, you have to go way, way back in history. The dramatic daily shifts between light and darkness on our planet because of sunrise and sunset have been incorporated into the biology of nearly every living thing. Our internal organs function differently during the day from how they do at night, in patterns known as circadian rhythms. Over the past few years, researchers have discovered that unnatural light exposure—such as staying up late amid the glare of a digital screen—disrupts these rhythms in ways that over time can lead to a host of illnesses.
6 But now experts have begun to suspect a second circadian clock in the body—organized around food, not light. Scientists still have much to learn about this food-based body clock, but evidence suggests that round-the-clock snacking may pose as much of a danger to our health as artificial light at night. Night eating has been implicated as a factor in diabetes, heart disease, cancer, and learning and memory problems.
7 Throughout evolution, daytime has been for nourishment and nighttime for fasting, and our organs have evolved accordingly. Digestive enzymes and hormones ebb and flow in a predictable pattern over the course of 24 hours, enabling the liver, intestines, and other digestive organs to function together as one well-oiled machine. Our modern world of late-night takeout and snack-filled pantries threatens to upend this calibrating role of food.
8 Compared with other kinds of diets, night fasting is simple. In a small pilot study, Ruth Patterson, Ph.D., a nutrition expert and epidemiologist at the University of California, San Diego, told women to eat dinner as early as 6 p.m. and definitely by 8 p.m. and not to eat again until eight in the morning, for at least 12 hours of "gut rest". "(Fasting) they instantly understood," Patterson says. "They didn't have to change what they ate or how they cooked."
9 The new research suggests that breakfast really is the most important meal of the day—but we need to embrace its original meaning: breaking a fast. The first meal of the day is most beneficial only if it comes after 12 to 14 hours of not eating or drinking, says Panda.
10 In addition to fasting at night, it's beneficial to eat your main meal earlier in the day. In a 2013 study, Harvard's Frank Scheer analyzed 420 dieters at weight-loss clinics. Participants ate the same number of calories and were equally active, but those who had their main meal before 3 p.m. lost significantly more weight than those who ate later. "To find such big differences in weight loss with just a slight difference in meal timing is quite remarkable," says Scheer.
11 To many, the science of meal timing is nothing but common sense. Craig Weingard is a bodybuilding expert who for years has included nightly fasts among his recommendations. For the longest time, Weingard resisted. It seemed too painful to go to bed hungry. Finally, he tried it. "In a flash, my whole body changed. I literally can see it the next day when I look at my stomach if I didn't eat after six," he says. "Anything you eat after 6:15 p.m. becomes part of you."
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