In an age of long commutes, late sports practices, endless workdays
and 24/7 television programming, the image of Mom hanging up her dish
towel at 7 p.m. and declaring "the kitchen is closed" seems a quaint
relic of an earlier era.
It also harks back to a thinner America. And that may be no coincidence.
A new study, conducted on mice, hints at an unexpected contributor to the nation's epidemic of
obesity
— and, if later human studies bear it out, a possible way to have our
cake and eat it too, with less risk of weight gain and the diseases that
come with it.
Just eat your cake — or better yet, an apple — earlier. Then wait 16 hours, until breakfast the next morning, to eat again.
"We
have to come up with something that is a simple alternative to calorie
counting," said Satchidananda Panda, a regulatory biologist at the Salk
Institute in La Jolla who led the study published online Thursday by the
journal Cell
Metabolism.
Panda
and his team put groups of mice on different eating regimens for 100
days. Animals in two of the groups dined on high-fat, high-calorie chow.
Half of them were allowed to eat whenever they wanted, and nibbled on
and off throughout the night and day. The other mice had access to food
only for eight hours at night, when they were most active.
In
human terms, this would be rough: No ice cream while watching "Glee." No
second glass of wine while talking things over with the spouse. Not
even a late-night glass of warm milk.
The difference was
astonishing. Even though they ate a high-fat diet, the mice who wrapped
up their eating day early and were forced to fast for 16 hours were lean
— almost as lean as mice in a control group who ate regular chow. But
the mice who noshed on high-fat chow around the clock became obese, even
though they consumed the same amount of fat and calories as their
counterparts on the time-restricted diet.
Extra weight wasn't their only problem. The obese mice developed high cholesterol, high blood sugar, fatty
liver disease
and metabolic problems. The mice who ate fatty food but were forced to
fast showed hardly any signs of inflammation or liver disease, and their
cholesterol and blood sugar levels were virtually indistinguishable
from those of mice who ate regular chow. When put on an exercise wheel,
they showed the most endurance and the best motor control of all the
animals in the study.
The data suggest that the stomach, the brain
and the body's digestive machinery need to take a break from managing
incoming fuel; otherwise, we may be working ourselves into a state of
metabolic exhaustion. When combined with high-calorie, high-fat diets,
the result is weight gain, a liver clogged with fat, accumulation of
cholesterol in the arteries and unused glucose in the blood.
In
the mice who fasted for 16 hours daily, measures of digestive hormones,
cholesterol and glucose suggested that liver enzymes were working hard
to break down cholesterol into bile acids. The body's stores of "brown
fat," the stuff that converts extra calories into heat, were revved up,
and the liver ceased production of glucose. As they burned fat, their
body temperatures were actually higher, Panda said.
The results of daily fasting were "phenomenal," he said.
If only we were mice.
Leo
Garcia, a 37-year-old auto mechanic whose adult years have been a
steady march up the scale, said he was intrigued by the notion that he
could lose some of his 250 pounds by wrapping up his mealtime early and
resisting the urge to nibble. "It seems easier to do something like that
than to join a gym and do cardio," he said.
But the study drew
both exasperation and cautious interest from obesity researchers, who
underscored that lab mice aren't tempted by fast-food restaurants with
late-night specials and have no alternative to the menu and feeding
schedule set by lab technicians. Being nocturnal, they also have
different circadian clocks. The conclusion that humans could prevent or
reverse obesity by wolfing down steak and chips for eight hours and then
stopping for 16 would be premature and almost certainly dangerous, some
said.
"I hope it's true, but I doubt it," said Barbara Corkey, director of obesity research at Boston University School of Medicine.
Barry M. Popkin, a nutrition expert at the
University of North Carolina,
said the study plies "uncharted territory" that needs exploration. A
clinical trial published in 1992 suggested that eating frequent, small
meals resulted in better insulin control and longevity.
"This one study cannot tell us that this science is wrong," Popkin said. "However, it is suggestive that scholars in the
diabetes, obesity and other areas related to
heart disease need to test this issue further in animals and humans."
Panda
acknowledged that his research would need to be refined and tested in
humans before it could be used to fight the war against obesity. The
16-hour fast that was so effective in preventing obesity in mice "may
not be a magic number" for people, he said.
But extending the
nighttime fast is a cheap and simple dietary adjustment that has no
discernible side effects and doesn't require anyone to count calories or
even deprive themselves — unless you just can't watch a playoff game
without a beer or can't fall asleep without tea and honey.
All you
need is a clock, said Panda, who noted that most after-dinner snacks
are high in fat, sugar, salt and calories, and are best cut out anyway.
Research
into the basic drivers of obesity — both social and biological — are
under greater scrutiny than ever. Pharmacological help for the nation's
78 million obese adults and 12.5 million obese children has been
elusive, as have the keys to behavior change for enduring weight loss.
Scientists acknowledge that obesity results from a complex mix of
genetic
and environmental factors, such as sedentary lifestyles, consumption of
sweetened soft drinks, growing portion sizes and the increasing role of
calorie-rich restaurant meals in American diets.
Panda thinks
researchers may be overlooking the role that timing has on the body's
response to food. In the agricultural lifestyle of an earlier time,
Americans ate heartily but were thinner. They did chores, then had a big
breakfast, followed by more physical activity, a hearty lunch, work and
an early dinner. Soon after the sun set, it was time to sleep.
"Most
people ate mostly in daytime," Panda said. Today, "our social life
starts at sunset. Family time starts at the evening. So essentially, we
have increased our eating time in the last 40 to 50 years."