How can lack of sleep keep me from losing weight?

Restricting the time you have in bed can cause you to suffer significant sleep deprivation. And sleep deprivation has some significant effects on weight loss:

• Hormone imbalance makes your appetite grow, so you feel full less.
• Losing the last hour of sleep in a full sleep cycle means losing REM sleep, the stage where you burn the most calories.
• Sleep deprivation causes food cravings for high-fat, high-carb treats.

If you're on a fitness/weight-loss plan but are sleeping only about 5.5 hours per night, you may be burning muscle instead of fat. That's the conclusion of a study of men and women on the same calorie-restriction diet who slept for 8.5 hours one week and 5.5 hours the second week. The dieters lost the same amount of pounds in each week, but in the sleep-deprived week, the subjects lost more weight from muscle than fat.