There are several risk factors for being overweight and obese. Some risk factors are genetic in nature while others are environmental. The environmental risk factors include overeating and lack of regular exercise. Sleep deprivation is a less well known risk factor for becoming overweight and obese. Sleep deprivation can lead to obesity by several different mechanisms. Previous research has shown that sleep deprivation causes weight gain by resulting in decreased leptin levels and increased ghrelin levels. Leptin is a hormone that is produced by adipose tissue and signals to the brain that satiety has been reached, while ghrelin is a hormone that produces hunger and simulates appetite. The dietary behavioral changes that occur as a result of sleep deprivation have not previously been studied.
Researchers, led by Dr. Leila Azadbakht from Isfahan University of Medical Sciences in Iran, have found that sleep deprivation causes poor diet choices and results in both general obesity and central obesity. The results of their study were published online in the journal Nutrition. The researchers performed a cross sectional study consisting of 410 females who were assessed for sleep duration, dietary intake, and diet quality indices (including dietary energy density, dietary diversity scores, healthy eating index, nutrient adequacy ratio, and mean adequacy ratio). The researchers found that study participants who slept less than 6 hours per night were more likely to be overweight or obese and have central or abdominal obesity. In addition, sleep deprivation caused study participants to consume more calories as carbohydrates, but have lower intake of fiber, fruits, whole grains, and beans. Diet quality indices were significantly lower in sleep deprived study participants as opposed to adequately rested study participants.
The authors wrote, “In this cross-sectional study, we found that short sleepers had significantly lower diet quality indices and higher values of [body mass index] and waist circumferences, as well as a higher percentage of obesity and abdominal adiposity compared to longer sleepers,without any significant differences in physical activity levels”.
The authors also wrote, “It has been well established that sleep curtailment is associated with lower concentrations of anorexigenic hormones in contrast with elevated serum levels of orexigenic hormones such as ghrelin”.
The authors concluded, “…total energy intake was higher among short sleepers and they had higher energy intake from carbohydrates, which was mainly accompanied by lower consumption of dietary fiber (i.e., whole grains and beans). These differences might be the reason for higher [body mass index] values and waist circumferences among short sleepers because the inverse association between diets rich in fruits, vegetables, and whole grains,which are categorized as low-glycemic-index foods, and weight gain has been confirmed by well-designed studies. It is worth noting that higher dietary intakes of total energy,carbohydrate, and high-glycemic-index foods would result in a decrement in serum concentrations of leptin. Furthermore, earlier studies have shown higher concentrations of ghrelin in short sleepers, which are likely to increase appetite and possibly explain the increased [body mass index] among short sleepers”.
This study is important because it confirms previous findings that sleep deprivation causes weight gain and increases the risk of obesity. In addition, this study shows that dietary choices are poorer in sleep deprived individuals which usually consist of high carbohydrate foods. From a physiological standpoint, these poor food choices cause decreased leptin and increased ghrelin which will drive overeating and obesity. Similarly, high carbohydrate diets cause excess insulin secretion that leads to increased adiposity. Future studies should confirm these findings on a larger scale and elucidate the reasons for these food choices.
Fahimeh Haghighatdoost et al. “Sleep deprivation is associated with lower diet quality indices and higher rate of general and central obesity among young female students in Iran” Nutrition August 30, 2012 doi:10.1016/j.nut.2012.04.015