Why Do You Lose Weight After a Night's Sleep?

If you've ever weighed at night before you go to bed and then again first thing the next morning, you noticed that there is usually a difference of anywhere from one to three pounds. You may have wondered how this could happen because you didn't seem to be expending any energy while you were asleep.

Although the number of calories burned while you are sleeping varies from person to person, Fit Day website reports that the average person burns about 77 calories per hour. That adds up to a little over 600 calories in an eight-hour night. The actual number of calories burned depends on the person's basal metabolic rate, or BMR. This is the minimum rate your body burns calories at while you are at rest. These calories support the body's breathing, heart rate, nervous system and temperature. Tall, thin people tend to have higher BMRs than shorter, rounder people, and men usually have higher ones than women. Sleeping in a cold room and being sick both raise your BMR, as do frequent periods of exercise throughout the day.

While you sleep and rest, your body has a chance to get back in balance from the tasks of the day. Excess fluid that has accumulated in the body during the day makes its way from your cells into the bloodstream. From the bloodstream it then moves into the kidneys. When you wake up in the morning, you go to the bathroom and urinate this extra fluid away. When you weigh yourself after visiting the bathroom, you are usually at your lowest weight of the day.

Getting a good night's sleep can actually help prevent obesity. When you are exhausted, you feel hungrier, and this can affect your judgment about what you eat. Most adults need about eight hours of sleep a night to feel refreshed, but this amount does vary. To find out what amount is best for you, find time during a week or two when you don't have to be awakened by an alarm clock and experiment with different times to go to bed and wake up. Then try going to bed at the same time and allow yourself to wake up when you feel rested. You'll eventually find a schedule that works best for you.

Results of a weight loss study were published in the March 29, 2011, online edition of the "International Journal of Obesity." The study followed 472 adults with obesity in phase one of the trial, and 60 percent of that number participated in phase two of the same study. The researchers found that the right amount of sleep and stress reduction at the trial's beginning predicted successful weight loss. The study showed that people were more likely to lose weight when not having to deal with sleep deprivation, stress or depression. The researchers believed that improving sleep may be as important to weight control efforts as changing diet or exercise. Another study presented at the American Heart Association's scientific sessions in Atlanta found that sleep-deprived adults ate an average of 300 more calories per day, mostly from saturated fat. The researchers from Columbia University followed 13 men and 13 women of normal weight as they spent six days sleeping four hours per night, then six days sleeping nine hours per night.