Or, as the saying goes, eat like a king at breakfast, a prince at lunch, and a pauper at dinner.
For as long as humans have been on the Earth, one thing has never changed -- the rising and setting of the sun each day. As a result our bodies have developed a 24-hour cycle, known as the Circadian rhythm, that tells us when we're tired or wakeful, usually around the same times each day. The hypothalamus is the gland that controls this, but exposure to light and darkness affect it as well.
Scientists have begun to understand that our Circadian rhythm also affects metabolism. The time of day (or night) that we eat either aligns with our rhythm or disrupts it, and if it's causing disruption it could be preventing the body from functioning optimally. An article in the New York Times explains the research of Dr. Satchin Panda, author of "The Circadian Code," who argues that
"people improve their metabolic health when they eat their meals in a daily 8- to 10-hour window, taking their first bite of food in the morning and their last bite early in the evening."
The reason for this is that our hormones, enzymes, and digestive systems are best prepared for food intake in the morning and early afternoon. That is when the pancreas increases production of insulin, required to control blood sugar, and the gut and its microflora communities are most active. At night, organs slow down and the brain releases melatonin, which signals to the body that it's time to sleep; if you're eating at the same time, it sends a mixed signal to the body, which is hardwired to interpret food intake as starting the day.
The New York Times quotes Dr. Courtney Peterson, a nutrition science professor at the University of Alabama:
"If you’re constantly eating at a time of day when you’re not getting bright light exposure, then the different clock systems become out of sync. It’s like one clock is in the time zone of Japan and the other is in the U.S. It gives your metabolism conflicting signals about whether to rev up or rev down.”
Dr. Panda's research supports this idea. In 2012 he conducted a study in which genetically identical mice were divided into two groups. Both were given fatty, sugary foods, but one group had access to the foods only within an 8-hour window, while the other had unlimited access.
"Despite both groups consuming the same amount of calories, the mice that ate whenever they wanted got fat and sick while the mice on the time-restricted regimen did not: They were protected from obesity, fatty liver and metabolic disease."
Dr. Panda performed another experiment on a group of pre-diabetic men, in which they were allowed a set amount of food during a 12-hour window for five weeks, and then were restricted to a 6-hour window following that. The result?
"On the time-restricted regimen, the men had lower insulin, reduced levels of oxidative stress, less nighttime hunger and significantly lower blood pressure. Their systolic pressure, the top number, fell by roughly 11 points, and their diastolic pressure dropped by 10 points."
In a world inundated with dietary advice, this may seem like yet another attempt to rein in the obesity and diabetes epidemics, but it is an interesting departure from the usual discussions about calorie-counting and elimination of specific foods. To think of one's diet in terms of timing offers new opportunity to people who have long been fighting weight gain or who want to improve their metabolic health in general.