If you want to lose weight, be sure to get enough sleep.
people know they should cut calories and exercise more to trim down,
but there's now significant scientific evidence that another critical
component to weight control is avoiding sleep deprivation, sleep
"There is no doubt that insufficient sleep
promotes hunger and appetite, which can cause excessive food intake
resulting in weight gain," says Eve Van Cauter, director of the Sleep,
Metabolism and Health Center at the University of Chicago. She has spent 15 years studying the topic.
deprivation probably affects every process in the body, she says. "Our
body is not wired for sleep deprivation. The human is the only mammal
that does this."
Her research and that of others may help explain
why so many people who are chronically sleep-deprived also are
overweight, and it could be part of the reason sleepy college students,
new parents and shift workers pack on pounds.
STORY: If you don't snooze, you lose
Studies have shown that when people don't get enough sleep they:
Have increased levels of a hunger hormone called ghrelin and decreased
levels of the satiety/fullness hormone called leptin, which could lead
to overeating and weight gain.
• Consume about 300 calories a day
more than when they are well-rested. Overall, most of the extra calories
came from high-fat foods.
• Snack more and do less physical activity.
Eat more than what is needed to cover the energy cost of staying awake
longer, especially at night, which can lead to significant weight gain.
has showed that when study participants didn't get enough sleep for
five days, they consumed more carbohydrates and gained nearly 2 pounds
in that time. "When people are sleepy, they make poor food choices and
are more likely to eat more than they need," says Kenneth Wright,
director of sleep and chronobiology laboratory at the University of Colorado in Boulder.
When those folks got enough sleep, they reduced their intake of both carbohydrates and fats, Wright says.
research shows that too little sleep also plays havoc with your fat
cells, which could lead to weight gain and type 2 diabetes, and that
making sure you get enough sleep will help fight a genetic
predisposition to gain weight.
Van Cauter says sleep deprivation
affects the body in many different ways. For instance, it activates a
small part of the hypothalamus, the region of the brain that also is
involved in appetite regulation.
In addition to ghrelin and
leptin, there are many other hormones involved in appetite regulation
that sleep deprivation may affect, she says. "We are looking at
endocannabinoids, which are increased in the afternoon in people who are
sleep-deprived. These hormones promote eating for pleasure, which is
called 'hedonic eating.'"
Another recent discovery is that not
getting enough sleep reduces fat cells' ability to respond properly to
the hormone insulin, which is crucial for regulating energy storage and
use, Van Cauter says.
Plus, insulin promotes the release of
leptin, so if your fat cells are less insulin-sensitive, you will make
less leptin, which is associated with an increase in food consumption
and weight gain, she says.
Insulin and leptin contribute
independently to fat intake or storage, says Matthew Brady, an associate
professor of medicine at the University of Chicago and senior author of
the study on sleep deprivation and fat cells. "There is a growing body
of evidence that agrees that sleep deprivation can lead to greater
chance of weight gain."
So how can you know if you're getting enough sleep?
vary, but in general, most young adults need seven to nine hours a
night, Van Cauter says. Some people can do with less, and others need
more. As people grow older, their need for sleep decreases to about
seven to eight hours a night, she says.
Yet, many people don't know exactly how much sleep they need.
Cauter recommends trying to get a handle on your sleep needs by doing
this: The next time you're on vacation, go to bed at your usual time,
but do not use an alarm clock to wake up. The first couple of days, you
may sleep more than usual. That way you will pay your sleep debt, she
Then, when your sleep has stabilized, record how much you
sleep, plus or minus 15 minutes, she says. That is your sleep need or