If you've ever weighed yourself before bed and then stepped back on the scale first thing in the morning, you've probably seen that weight loss occurs naturally overnight. However, the missing pounds typically come right back after eating and drinking, since most of that weight comes from water loss. That said, people who sleep well may have an easier time slimming down, so don't skimp on your beauty rest.
Weight Lost Sleeping
The precise amount of weight lost during slumber varies from person to person, but a study presented at an Associated Professional Sleep Societies meeting in 2009 quantified weight loss among a small sample of healthy young men. Researchers found that the average participant shed 1/4 pound per hour while asleep, which was more than triple the amount lost while lying awake in bed. This difference may be partially attributed to hormonal changes as well as the fact that the brain is highly active during REM sleep, causing you to burn more calories.
Despite the weight loss, you don't shed a significant amount of fat as you sleep. A 155-pound person burns about 23 calories in 30 minutes while sleeping, according to Harvard Medical School, which translates to just 368 calories over eight hours. Shedding 1 pound of fat requires a deficit of 3,500 calories, so you can only lose about 1/10 pound of fat after a full night of sleep.
Most of the weight lost during sleep likely comes from fluid loss. You emit water vapor with each breath you take, and sweating further contributes to dehydration. Plus, if you get up to use the restroom during sleep you'll lose even more water. Duke University Health System estimates that the average adult loses 2.5 liters of water per 24-hour period through respiration, sweat, urine and bowel movements. Each liter contains approximately 4 cups and weighs about 2 pounds.
Sleep for Weight Loss
While you won't get much leaner after one night's rest, adopting healthy sleep habits may help you reach your weight-loss goals in the long run. "Scientific American" reports that the prevalence of both obesity and lack of sleep have risen in the United States over the past few decades. Although that fact alone does not confirm a causal link, researchers have found that the longer people sleep, the higher their levels of leptin, a hormone that triggers feelings of fullness, and the lower their levels of ghrelin, a hormone that triggers hunger. For healthy hormone levels, aim for seven to eight hours of sleep per night.