Today's hot topic is about lack of sleep, and weight loss. Scientists have known for years that skimping on sleep can and does lead to weight gain, but how? One good example is a study that was published in 2005. They looked at 8,000 adults as part of the National health and Nutrition Examination survey. They found that sleeping fewer than seven hours a night corresponded with a greater risk of weight gain and obestity, and the risk was actually increased for every hour of lost sleep.
From this study, more studies have been done to try and pinpoint the exact reason this happens. One was published this year in the The American Journal of Clinical Nutrition. They took a group of men and measured their food intake across two 48-hour periods. One time they slept eight hours, and the other time they slept only four. After the night of sleeping only four hours, the men consumed more than 500 extra calories (about 22% more), than they did after eight hours of sleep. An extra 500 calories adds up to a pound weight gain a week! The University of Chicago did a similar study last year and had similar findings in both men and women. After five and half hours sleep, the participants took in significantly more calories from snacks and carbohydrates, than after eight hours sleep.
These studies have been able to place the blame on hormones, ghrelin, and leptin. After a lack of sleep, the hormone ghrelin spikes, and Leptin is reduced. Ghrelin is a hormone that stimulates the appetite. Leptin is a hormone that signals satiety. More research is needed to study these hormones and their actions.
The bottom line is that losing sleep may increase appetite, and as a result, increase weight.