Increased risk of dangerous visceral fat has been linked to insufficient sleep, a new study has found.
New research from the Mayo Clinic reports that not enough sleep led to a nine percent increase in the total abdominal fat area and an 11 percent increase in abdominal visceral fat.
Visceral fat is found deep inside the abdomen around organs and is strongly linked to cardiac and metabolic diseases.
Inadequate sleep was linked to a higher calorie intake, a very small increase in weight, and a significant increase in fat accumulation inside the belly even in young, healthy, and relatively lean people.
The study, published in the Journal of the American College of Cardiology, noted that lack of sleep is "often a behaviour choice" that has become more widespread.
Researchers said more than a third of US adults do not get enough sleep due to shift work, smart devices and social networks used during traditional sleep hours.
Additionally, people tend to eat more but not increase physical activity if they are awake longer.
Even with catch-up sleep, researchers found that visceral fat increased despite a decrease in calorie intake.
Not sleeping enough appears to redirect fat to be placed in the more dangerous abdominal visceral area.
"This suggests that inadequate sleep is a previously unrecognised trigger for visceral fat deposition, and that catch-up sleep, at least in the short term, does not reverse the visceral fat accumulation," said Dr Virend Somers, the principal investigator of the study.
"In the long term, these findings implicate inadequate sleep as a contributor to the epidemics of obesity, cardiovascular and metabolic diseases."
Dr Somers added that interventions, such as more exercise and healthy food choices, need to be considered for people who cannot easily avoid sleep disruption, like shift workers.
The belly fat sleep study
The study consisted of 12 healthy non-obese people who were not limited in food choice.
Over two 21-day sessions, participants were randomly assigned to the control (normal sleep) group or restricted sleep group during one session.
After a three-month break, they were put in the opposite group during the next session.
Researchers monitored and measured energy intake, energy expenditure, body weight, body composition, fat distribution (including visceral fat or fat inside the belly), and circulating appetite biomarkers.
The first four days were an acclimation period. During this time, all participants were allowed nine hours in bed to sleep.
For the following two weeks, the restricted sleep group were allowed four hours of sleep and the control group continued with nine hours.
A three day recovery period followed in which both groups had nine hours of sleep.
Researchers found that participants consumed more than 300 extra calories per day during sleep restriction, eating approximately 13 percent more protein and 17 percent more fat, compared to the acclimation stage.
The increase in food consumption was highest in the early days of sleep deprivation and then tapered off to starting levels during the recovery period.
"The visceral fat accumulation was only detected by CT scan and would otherwise have been missed, especially since the increase in weight was quite modest — only about a pound," said the study's leader, Dr Naima Covassin.
"Measures of weight alone would be falsely reassuring in terms of the health consequences of inadequate sleep. Also concerning are the potential effects of repeated periods of inadequate sleep in terms of progressive and cumulative increases in visceral fat over several years."
The authors said more research is needed to see how these findings relate to healthy young people in comparison to those who are higher risk, such as people who are obese or have metabolic syndrome or diabetes.
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