[su_dropcap style=”default” size=”3″ class=””]F[/su_dropcap]or the past 10 years, sleep researchers Patel and Hu, have completed extensive reviews of published literature on obesity and sleep between 1966 and 2007. Longitudinal studies have demonstrated that sleeping less than 7 hours or over 9 hours each day increases mortality risk; also long and well known is the high morbidity and mortality of obesity. This evidence provides the foundation for acceptance of a strong correlation between sleep and weight. Compelling results in the journal, Obesity, found a dramatic increase in both weight gain and sleep deprivation in 40 percent of Americans over the past decade. As scientific discovery continues to reveal the relationship between weight gain and sleep, significant experimental studies begin to take shape beginning in 2008.
[blockquote type=”intext”]“When subjects shifted from insufficient sleep to an acceptable amount of sleep, food intake decreased, particularly consumption of fats and carbohydrates, resulting in meaningful weight loss.”[/blockquote]
Recent Findings on Sleep and Weight
Fast forward to 2013: Experimental studies on sleep and weight are now well documented. A research trial carried out by Markwaid and colleagues, in Colorado, U.S. studied insufficient sleep, total body energy expenditure, and weight. The study established that 5 days of 5 hours of sleep is not only energy-taxing, but sleep deficit also triggers food intake in excess of the energy required by the body; thus, contributing weight gain. A delay in the melatonin hormone onset alters the circadian rhythm, leading to a circadian drive for an increase in food intake at night. The study found that post-meal intake of carbohydrate, protein and fiber calories rose by 42% during sleep loss.
When subjects shifted from insufficient sleep (approximately 5 hours) to an acceptable amount of sleep (7 to 9 hours), food intake decreased, particularly consumption of fats and carbohydrates, resulting in meaningful weight loss. Researcher’s next steps are to study satiety and hunger hormones suspected to explain the effect of sleep loss on weight gain. The identified hormones released include: leptin from fat tissue; ghrelin from the stomach lining; and Peptide YY from the small intestine. Thus far, hormone studies have been inconclusive.
Not only does sleep deficit often result in weight gain, but the reverse is also true: weight gain can impact duration and quality of sleep. This can perpetuate a negative cycle that can harm health. A study detailing this finding can be found here.
The Bottom Line
Comprehensive studies support the relationship between sleep and weight. Independent associations exist between short sleep duration and weight gain; whereas, weight loss and decreased food intake show a direct relationship to sleeping longer. By understanding the physiological and behavioral mechanism behind sleep loss, scientist may offer breakthroughs in making it easier to lose or maintain weight.
Studies on short sleep hours and weight loss continue. Scientists such as Greer and colleagues are now conducting novel lines of research on appetite-regulating hormones and elevated caloric intake in relation to central brain function using functional MRI. Uncovering sleep-dependent neural dysfunction might lead to explaining the link between sleep loss and obesity. This research could elucidate what mechanisms increase our body’s energy expenditure without driving us to eat more.
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