MIDNIGHT SNACKS, SECOND BREAKFASTS, LATE NIGHT BITES, MIDMORNING
NOSH.
As a culture, we eat around the clock, incorporating food into social gatherings, work hours and
even downtime. Case in point: One study conducted by the Salk Institute for Biological Studies
in La Jolla, California, asked participants to use a mobile app to track everything they ingested
over the course of a day. More than half the participants reported eating for a span of 15 hours or
longer — almost from the time they woke up until when they turned in for the night.
But is all-day dining a problem? If you stick to healthy, whole foods and keep an eye on your overall
caloric intake, is there really any diff erence between eating three squares before 7 p.m. and nibbling
on a dozen mini-meals right up to bedtime? As it turns out, when you eat is just as important as what
you eat. Thought the explanation is hundreds of thousands of years old, scientists are just beginning to
understand it, thanks to recent research on circadian rhythms and the body’s internal clock.
You could actually improve your overall health (and shrink your waistline) just by changing
when you eat. Read on to learn about
the research so groundbreaking that it won the Nobel Prize.
dinner?
(and Breakfast, and Lunch …)
The Body Clock
The phenomenon known as the circadian rhythm is based
on the rotation of the earth. As part of our species’ evolution, our bodies have adapted to
daylight and nighttime, regulating certain biological functions accordingly — sleep,
metabolism and hormone production, to name a few.
In 2017, three American scientists won the Nobel Prize in Physiology or Medicine for their
discovery that all multicellular organisms — humans included — have so-called “clock” genes that dictate wake and sleep
patterns. They found that these genes still continue to function
even when the organism (a fruit fl y, in this case) was kept
in complete darkness, proving that our internal clock doesn’t
just react to light and day — it actually keeps time along with it. And that internal
timekeeper is very picky about when we should and should not be eating.
Timing Is Everything
Pamela M. Peeke, M.D., MPH, assistant professor of medicine at the University of Maryland and author of The Hunger Fix:
The Three-Stage Detox and Recovery Plan for Overeating and Food Addiction (Rodale, 2012), explains that our natural eating
patterns are part of our “primal software.” Cave women, she reasons, ate early in the day
when they woke up hungry, and food was readily available and easiest to procure. Nighttime
was for sleeping and hiding from predators.
Even though we no longer have to worry about T. rex and modern refrigeration keeps our
favorite eats within arm’s reach 24/7, we’re better off sticking to our ancestors’ more
restricted feeding schedule for a variety of reasons.
First, certain times of day are more conducive to processing certain macronutrients — aka
carbohydrates, proteins and fats. While healthy fats like avocado, nuts and olive oil can
be eaten throughout the day, Peeke suggests consuming the majority of your
carbohydrates (bread, grains, fruits, starchy vegetables, etc.) in the morning and early afternoon.
“Up until about 3 p.m., you’ve got diff erent insulin secretion and therefore have a more
optimal glucose-burning engine going at that time,” Peeke explains. “It becomes
less and less effi cient after 3 p.m.” Lunch should be your biggest meal of the day, and for
dinner, your focus should be on lean protein, healthy fat and lighter, water-based carbs like
broccoli and green beans.
Second, your body requires periods of nonfeeding to perform a host of reparative functions.
Satchin Panda, Ph.D., a professor at the Salk Institute and author of The Circadian Code (Rodale, 2018),
explains that about six to eight hours after your last meal, your body switches from burning
available sugar and glycogen stores to burning fat. Besides producing ketones, which
have been shown to improve brain function, this fat-burning phase runs parallel with an
important detoxifying process called autophagy. “The body will go around and see whether
there’s any recyclable material available and recycle it,” Panda explains. By sweeping up
damaged proteins and organelles (structures within a cell), autophagy helps
counteract disease and aging.
Your gut (specifi cally your gut lining and microbiome) also requires a break from digestion,
since it works all day breaking food into fuel.
According to Panda, the gut generates a new lining every 10 to 15 days: Every night your
body removes 7 to 10 percent of the old cells and replaces them with new cells. “You
cannot repair a road when the traffi c is still moving,” Panda says. “That’s why you cannot
repair gut lining properly if you just ate and went to sleep.”
Graze No More
So how long should you refrain from eating in order to get the optimum benefi ts? Research
suggests at least 12 to 14 hours.
The same study that revealed our propensity for all-day
grazing eventually introduced its participants to “eating windows.”
Those who typically ate over the course of 14 hours or longer were
asked to restrict their eating to between 10 and 12 hours. They
were allowed to choose their own time frame and were not
required to alter their caloric intake or change the quality of their food. After 16 weeks,
participants reported multiple benefi ts and expressed an interest in continuing with time-restricted
eating. According to Panda, who co-wrote the study, participants
experienced higher energy levels and deeper sleep.
“
Deep sleep is very important because only [then] do we
produce growth hormone, and that repairs our gut lining, our
skin and some muscle,” he says.
Participants also lost an average of 7.2 pounds, most of which they kept off for one year after the study.
Of course, one could argue that by limiting the number of hours during which you can eat,
you may naturally cut calories (and dodge lessthan- nutritious late-night temptations). However, another
study conducted by Panda and his team compared the health
outcomes of two groups of mice — one with unrestricted
access to food and another with access to the same exact amount
of calories but only over the course of 10 hours. Even though
they consumed the same diet, the mice with free rein became
obese and developed metabolic diseases while the mice who
ate within a 10-hour window remained healthy.
The take-away? Even a diet fi lled exclusively with nutritious
foods can work against your health and fi tness goals if it’s
not timed properly. Mind your body’s clock, feed it properly
and you’ll soon be in sync.
RESTRICTION ≠ DEPRIVATION
In practice, eating according to your circadian rhythm isn’t particularly diffi cult.
With a little extra planning and few adjustments to your current schedule, you can reap the
benefi ts of time-restricted eating without feeling deprived. Here are a few basic guidelines to get you started.
. Plan your macronutrients accordingly. Consume the majority of your carbs before 3 p.m.
when your body most effi ciently burns glucose. In the late afternoon and early evening,
focus on protein, cruciferous, and leafy vegetables and healthy fats.
. Take note of the time when you take your fi rst bite of the day (yes, coff ee with milk and/or
sweetener counts), then time your last meal so you fi nish eating 12 hours or less later. For example, if
you grab a breakfast wrap at 7 a.m., fi nish eating dinner by 7 p.m.
. If you eat your last meal a bit later than you’d like, Pamela M. Peeke suggests delaying
your breakfast the following morning to allow for
an adequate nonfeeding period. While you don’t always have control over dinner (no one’s
suggesting you force the early-bird special on all your friends), you usually have the fi nal
say on when you eat breakfast.
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