By now we have learned to become skeptical of the late- night infomercials boasting weight loss methods that seem too good to be true.  Simply “pop a pill” or “make a shake,” or “eat all you want, and never exercise,” everyone seems to have the easy answer how to drop the poundage.  All, of course, for a portion of your income.  But what if I told you the real answer is as simple (and free) as turning off the TV and getting some z’s?  That definitely sounds too good to be true, right?

Maybe not!  It seems that more and more research is emerging showing a link between sleep and weight loss.  The research shows that people who get more than 6 hours of sleep each night tend to be leaner than those who sleep less.  The theory behind this phenomenon can be accredited to two naturally occurring hormones: leptin and ghrelin.

Leptin

 Leptin is a hormone produced by fat cells that signals to the brain when you are full and should stop eating.  Levels of this hormone are generally low before a meal and increase after a meal.  Studies have shown that levels of leptin are decreased in people who are sleep deprived (sleep less than 6hrs/night).  Therefore, it has been suggested that inadequate sleep can decrease a person’s ability to recognize satiety, and lead to probable overeating and weight gain.

Ghrelin

Ghrelin, a.k.a the “hunger hormone,” is produced in the gastrointestinal tract and is responsible for stimulating appetite. Levels of this hormone are generally increased before a meal, and decreased after a meal.  Studies have shown that levels of ghrelin are increased in people who are sleep deprived.  Therefore, it is suggested that inadequate sleep can result in increased appetite and intake, and a consequential weight gain.

In short, decreased sleep results in decreased leptin and increased ghrelin which results in increased appetite and decreased satiety.  This seems like a simple enough concept to explain the role of sleep in the maintenance of a healthy weight.  However, just like weight loss, the effect these hormones have on dietary habits is a bit more complicated.

The Outliers

Knowing what we know about leptin and ghrelin, we might expect to find low levels of leptin and high levels of ghrelin in obese people.  However, when tested, it was found that obese people have higher levels of leptin and lower levels of ghrelin when compared to thinner people.  This seems counterintuitive since high levels of leptin and low levels of ghrelin are associated with decreased appetite and intake.

This phenomenon can be explained by something researchers call “leptin resistance.”  In the same way a person with diabetes can be resistant to insulin, some obese people seem to be resistant to leptin.  It is believed that these people are prone to overeat because their brain never receives the signal of being full, despite the high levels of leptin.  Therefore, the sleep habits of these particular people will most likely not have the same effect on their weight status as it could for someone who is not resistant to leptin.

On the opposite end of the spectrum are the hormone levels in people with anorexia or cancer induced cachexia (extreme weight loss).  The levels of ghrelin, or the “hunger hormone,” are very high in these individuals, despite their lack of appetite.  This occurrence has yet to be explained.

Because there are still unknowns in regards to leptin and ghrelin, and their role in dietary habits, researchers are reluctant to definitively link increased sleep to weight loss.  This, in spite of the concrete evidenced that sleep does indeed increase leptin and decrease ghrelin.  But do not be too quick to categorize sleep as another “too good to be true” weight loss method along with so many other gimmicks.

Sold on Sleep

Unlike the other weight loss gimmicks, sleeping more is truly natural and does not have potential hazardous side effects (unless you are late for work because you slept in).  Our bodies require adequate rest in order to function properly.  Despite the effect sleep has on different hormones and whether or not these hormones can lead to weight loss, there are other reasons sleep can still be a useful tool in beating the bulge.

Being well rested can create a very positive cycle to aide in weight loss.  The more rested someone feels, the more energy he or she can have to exercise.  In addition to the calories burned during exercise, it has been shown that people who exercise, sleep better.  This restarts the cycle of increased energy, exercise, calories burned, and weight lost!

Going to bed at a decent hour also lends itself to a decrease in late- night snacking.  Although the time food consumed does not play a role in weight loss or gain, the type of foods consumed is definitely important (see “Weight Loss Myths”).  Typically the foods we choose to snack on at night are not carrots and celery, but instead, ice cream and cookies.  This habit is a major obstacle when it comes to weight loss, but can be avoided by going to bed before late- night snacking begins.

Last, when people are not well rested, they often look to foods high in sugar as a “pick-me-up.”  These foods tend to be high in calories and promote weight gain.  In addition, “simple sugars” provide only a temporary fix to increasing energy, and then it is right back to feeling tired.  This can lead to either a vicious cycle of eating more and more sugar, or a lack of energy to exercise, or worse worst of all, both!

Lie Down and Relax

So in short, there still needs to be more research on the hormones leptin and ghrelin, how sleep affects them, and their role in maintaining a healthy weight.  However, increased sleep can definitely result in increased energy for exercise, and decreased reliance on high- calorie, sugary foods.  So although this no cost, risk- free method to aide in weight loss may seem too good to be true, it is certainly worth a try.  In the end, even if it does not result in you reaching your goal weight, good sleep habits can be developed, leading to a healthier, more rested you.
 
References:

Bouchez, Colette.  The Dream Diet: Losing Weight While you Sleep.  01 January 2009 WebMD.com.  29 May 2009.  http://www.webmd.com/sleep-disorders/guide/lose-weight-while-sleeping

Crispim CA, Zalcman I, Dattilo M, Padilha HG.  The influence of sleep and sleep loss upon food intake and metabolism.  Nutr Res Rev. 2007 Dec;20(2):195-212.

 “Ghrelin”  21 May 2009.  Wikipedia.org.  3 June 2009.  http://en.wikipedia.org/wiki/Ghrelin

“Leptin”  22 May 2009.  Wikipedia.org.  3 June 2009.  http://en.wikipedia.org/wiki/Leptin