02/01/2011 11:32 am ET | Updated May 25, 2011

Sleep: The Missing Piece to the Weight-Loss Puzzle?

When I started blogging for my favorite blog site, The Huffington Post, (shameless, I know), Arianna was on a mission to get more sleep and blogging about the changes more z's made in her life (Sleep Challenge 2010). A difficult lifestyle change to embrace for a woman who squeezes 26 hours into a 24-hour day!

The benefits of more shut-eye are abundant. Researchers have found sleep improves so many aspects of our lives, from having a better memory, to performing better on tests, to reducing inflammation and even having more success in the weight loss department. If you're skimping on sleep and putting on pounds, there's probably a connection.

That new exercise regimen and new eating plan you undertook for the new year are not the entire solution to an expanding waistline. The missing piece to this puzzle could lie in your sleep habits. According to a study published in the Oct. 5, 2010 issue of the Annals of Internal Medicine, overweight adults on a low calorie diet lost 55 percent less body fat when the slept only 5.5 hours a night versus when they slept 8.5 hours a night.

The same 10 people were tested in two, two-week intervals. Interestingly, they lost the same amount of total weight in each of the two-week tests, about 6.6 pounds. But, and this is a big but, the weight lost during the 5.5 sleep test was mostly lean body tissue and very little fat, whereas during the longer sleep test, they lost more fat and less lean body tissue. This is key because the total number of pounds you lose on the scale isn't nearly as important as the amount of body fat you lose. Remember: pound for pound, muscle weighs more than fat. When you lose muscle, sure, the number on scale goes down, but so does your body's metabolism, meaning your body burns less calories per day in general.

And that's not all the study found. The shortened hour sleep test showed the subjects had higher levels of ghrelin in their system -- the hormone that stimulates appetite. This is actually consistent with past research that shows inadequate sleep raises gherlin levels and reduces leptin levels -- the hormone that makes you feel satiated.

Is this good news or bad news to you? Sleep on it and share your thoughts or experiences with me.