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It’s not
just
what you
eat, but
the time
of day
you eat
it
By
Anahad
O’Connor
washingtonpost.com
Most
people
know
that
what and
how much
you eat
plays a
major
role in
your
health.
But
scientists
are
finding
that
when you
eat can
make a
difference
as well.
Studies
show
that for
optimal
health,
it’s
best to
consume
most of
your
calories
earlier
in the
day
rather
than
later —
for
example
by
eating a
large
breakfast,
a modest
lunch,
and a
small
dinner.
This
pattern
of
eating
aligns
with our
circadian
rhythms,
the
innate
24-hour
clock
that
governs
many
aspects
of our
health,
from our
daily
hormonal
fluctuations
and body
temperatures
to our
sleep-wake
cycles.
Because
of the
way our
internal
clocks
operate,
our
bodies
are
primed
to
digest
and
metabolize
food
early in
the day.
As the
day
progresses,
our
metabolisms
become
less
efficient.
Studies
show
that a
meal
consumed
at 9
a.m. can
have
vastly
different
metabolic
effects
than the
same
meal
consumed
at 9
p.m.
The
study of
meal
timing
This
emerging
field of
research,
known as
chrono-nutrition,
represents
a
paradigm
shift in
how
nutrition
researchers
think
about
food and
health.
Instead
of
focusing
solely
on
nutrients
and
calories,
scientists
are
increasingly
looking
at meal
timing
and
discovering
that it
can have
striking
effects
on your
weight,
appetite,
chronic
disease
risk and
your
body’s
ability
to burn
and
store
fat.
“This is
something
that
until
recently
no one
in
nutrition
had
looked
at —
it’s
always
been
what are
you
eating,
and
what’s
the
energy
content
of your
food or
the
carbohydrates,
protein
and
fat,”
said
Marta
Garaulet,
a
professor
of
physiology
and
nutrition
at the
University
of
Murcia
in Spain
who
studies
meal
timing
and its
effects
on
obesity
and
metabolism.
In
today’s
busy
world,
it’s
common
for
people
to skip
breakfast
and
binge at
night
after a
long day
at work.
Researchers
say that
whenever
possible
it would
be
better
to do
the
opposite
— or at
least to
space
your
dinner a
few
hours
from
your
bedtime.
Garaulet
has
found in
her
research
that
even in
her
native
Spain,
which is
famous
for its
late-eating
culture,
people
who
typically
eat a
large
midday
lunch
and a
light
dinner
develop
fewer
metabolic
problems
than
people
who
consume
a lot of
nighttime
calories.
“In
Spain
our main
meal is
in the
middle
of the
day,
from 2
to 3
p.m.,”
she
said.
“We eat
35 to 40
percent
of our
calories
in the
middle
of the
day. And
even
though
we eat
dinner
late, we
don’t
eat very
much.”
A big
breakfast
and a
light
dinner
When you
eat your
meals is
just one
of many
dietary
factors
that can
influence
your
metabolic
health.
And for
some
people,
like
night-shift
workers,
it’s
impossible
not to
consume
meals
late at
night.
But for
those
whose
schedules
permit,
research
suggests
that
having
your
biggest
meal of
the day
in the
morning
or
afternoon
rather
than at
night
could be
beneficial.
In a new
study
published
in
Obesity
Reviews,
scientists
looked
at data
from
nine
rigorous
clinical
trials
involving
485
adults.
They
found
that
people
who were
assigned
to
follow
diets
where
they
consumed
most of
their
calories
earlier
in the
day lost
more
weight
than
people
who did
the
reverse.
They
also had
greater
improvements
in their
blood
sugar,
cholesterol
levels
and
insulin
sensitivity,
a marker
of
diabetes
risk.
In
another
study
published
in Cell
Metabolism
in
October,
scientists
recruited
a group
of
adults
and
examined
what
happened
when
they
followed
an early
eating
schedule
for six
days.
The
schedule
included
breakfast
at 8
a.m.,
lunch at
noon,
and
dinner
at 4
p.m.
On a
separate
occasion,
they had
the same
participants
follow a
late-eating
schedule,
with
each
meal
pushed
back
four
hours
over a
six-day
period.
The
study
was
small
but
tightly
controlled,
involving
16
people
who were
closely
monitored,
provided
all
their
meals,
and kept
on a
strict
sleep
and wake
schedule
in a
laboratory
setting.
Why
late-eating
makes
you
hungrier
The
researchers
found
that
despite
eating
the same
foods
and
maintaining
the same
levels
of
physical
activity,
the
participants
were
significantly
hungrier
when
they
followed
the
late-eating
schedule.
A look
at their
hormone
levels
showed
why:
Eating
later
caused
their
levels
of
ghrelin,
a
hormone
that
increases
appetite,
to
spike,
while
simultaneously
suppressing
their
levels
of
leptin,
a
hormone
that
causes
satiety.
The
study
found
that
eating
later
caused
the
participants
to burn
less fat
and
fewer
calories,
and
pushed
their
fat
cells to
store
more
fat.
“To our
surprise
we found
that
these
mechanisms
were all
three
consistently
changed
in the
direction
that
would
promote
weight
gain,”
said
Frank
Scheer,
the
senior
author
of the
study
and the
director
of the
Medical
Chronobiology
Program
in the
Division
of Sleep
and
Circadian
Disorders
at
Brigham
and
Women’s
Hospital.
Other
studies
have had
similar
findings.
In one
randomized
trial at
Johns
Hopkins,
scientists
found
that
healthy
young
adults
burned
less fat
and had
a 20
percent
increase
in their
blood
sugar
levels
when
they ate
dinner
at 10
p.m.
compared
with
when
they ate
the same
dinner
on
another
occasion
at 6
p.m.
“It’s
clear
that the
timing
of your
meals
does
matter —
not just
what you
eat, but
when you
eat it,”
said
Jonathan
Jun, an
associate
professor
of
medicine
at Johns
Hopkins
and an
author
of the
study.
“Eating
late
makes
you less
glucose
tolerant
and also
makes
your
body
burn
less fat
than if
you had
the same
food
earlier
in the
day.”
How to
follow
an
early-eating
schedule
Scientists
who
study
meal-timing
say the
following
strategies
could
help you
optimize
your
health.
Don’t
skip
breakfast.
Garaulet
and her
colleagues
found
that
skipping
your
morning
meal
increases
your
risk of
obesity.
Mornings
are when
our
bodies
are
primed
to
metabolize
food. If
you’re
not
usually
hungry
in the
morning,
have
something
light,
then eat
a large
lunch.
“Try to
eat the
majority
of your
calories
during
the
morning
or
afternoon
but not
at
night,”
Garaulet
said.
Morning
carbs
are
better
than
late-day
carbs.
If
you’re
going to
eat
sweets
or
simple
carbs
like
bread,
pasta
and
pastries,
it’s
better
to do so
in the
morning
or early
afternoon,
when we
are most
insulin-sensitive,
rather
than at
night,
Garaulet
said.
Try to
eat
dinner
early in
the
evening.
Start by
moving
your
dinner
at least
one hour
earlier
than
usual.
Ideally
you
should
aim to
eat
dinner
at least
two to
three
hours
before
going to
bed.
Make
dinner
the
smallest
meal of
the day.
Even if
you
can’t
eat an
early
dinner,
you
should
try to
make
breakfast
and
lunch
your
biggest
meals of
the day
and
dinner
your
smallest.
If
you’re
used to
eating a
small
lunch
and a
big
dinner,
then
switch
the
order.
You can
make
your
dinner a
meal
that’s
heavy on
vegetables
to
lighten
it up.
“Just
try to
shift
more of
your
calories
to
breakfast
and
lunch,”
said
Courtney
Peterson,
an
associate
professor
in the
department
of
nutrition
sciences
at the
University
of
Alabama
at
Birmingham.
Try
meal-timing
at least
five
days a
week.
Sometimes
it’s not
practical
to eat a
small or
early
dinner,
and
that’s
okay. In
studies,
Peterson
found
that
people
who ate
a light
dinner
five
days a
week
instead
of seven
still
gained
benefits
like
better
blood
sugar
control
and less
daily
fatigue.
“Don’t
think of
this as
all or
nothing,”
said
Peterson.
“Maybe
on some
days you
can’t do
it
because
you’re
going
out to
eat with
your
family.
But then
on other
days you
can do
it and
that’s
great.
It’s
important
that you
do
what’s
practical
for
you.”
The
biology
of meal
timing
Scientists
have
uncovered
several
mechanisms
that
explain
why an
early-eating
schedule
is
better
for your
health.
Our
bodies
are
better
able
secrete
insulin,
a
hormone
that
controls
blood
sugar
levels,
in the
morning.
We also
tend to
be more
insulin-sensitive
early in
the day,
meaning
our
muscles
are
better
able to
absorb
and
utilize
glucose
from our
bloodstreams.
But as
the day
progresses,
we
become
less and
less
insulin-sensitive.
By
nighttime,
the beta
cells in
the
pancreas
that
produce
insulin
become
sluggish
and less
responsive
to blood
sugar
elevations.
Another
important
factor
is
hormone-sensitive
lipase,
an
enzyme
that
releases
fat from
our fat
cells.
This
enzyme
is
typically
most
active
at night
so it
can
provide
our
bodies
with
energy
to keep
our
organs
functioning
as we
sleep.
But
Garaulet
has
found
that
eating
late at
night
suppresses
this
enzyme —
essentially
preventing
your
body
from
burning
fat. “We
see a
big
difference
between
people
that
have
dinner
for
example
four
hours
before
going to
bed,”
she
said,
“and
those
that
have
dinner
around
one hour
before
going to
bed.”
Do you
have a
question
about
healthy
eating?
Email
EatingLab@washpost.com
and we
may
answer
your
question
in a
future
column.
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