Sleep loss promotes increase in abdominal fat, cardiometabolic risk

Healthy nonobese adults consumed more calories, gained more weight and experienced an increase in visceral adipose tissue after 14 days of experimental sleep restriction compared with those who slept 9 hours per night, researchers reported.

In a small study, described as the first-ever assessing the effects of sleep curtailment on body fat distribution, the researchers noted that an expansion in abdominal adipose tissue and especially visceral fat deposition occurred only in response to shortened sleep.

“Short sleep appears also to modulate nutritional choices, with sleep-restricted participants consuming significantly more fat and protein, which is consistent with previous data,” Virend K. Somers, MD, PhD, Alice Sheets Marriott Professor and director of the cardiovascular and sleep facilities at the Mayo Clinic’s Center for Clinical and Translational Science in Rochester, Minnesota, and colleagues wrote.

Experimental sleep restriction

In a randomized controlled crossover study, Somers and colleagues analyzed data from 12 healthy adults without obesity (nine men; mean age, 27 years). Participants completed a 21-day inpatient study comprising 4 days of acclimation and then 14 days of a restricted sleep intervention, defined as a 4-hour sleep opportunity, or a 9-hour sleep opportunity (controls), followed by a 3-day recovery segment. Study periods were separated by a washout interval of at least 3 months. Participants were also studied in a sedentary setting with ad libitum food access. Researchers took repeated measures of energy intake, energy expenditure, body weight, body composition, fat distribution and circulating biomarkers. The primary outcome was mean change in daily calorie intake from acclimation to experimental phase, assessed as the difference between sleep restriction and control conditions.

The findings were published in the Journal of the American College of Cardiology.

Compared with controls, those who experienced sleep restriction consumed more calories, with a between-condition difference of 308.1 kcal per day (95% CI, 59.2-556.8; P = .015), increasing protein (P < .05) and fat intake (P < .046); however, energy expenditure was unchanged.

Body weight increased for participants during both experimental sleep restriction and control sleep, though the magnitude of increase was greater after sleep restriction, with a net gain of 0.5 kg (95% CI, 0.1-0.8; P = .008).

There were no between-group changes in total body fat; however, total abdominal fat increased only during sleep restriction (P < .011), with significant increases evident in subcutaneous and visceral abdominal fat depots (P < .047 and P < .042, respectively).

“This study shows that prolonged experimental sleep restriction in an obesogenic setting promotes excess energy intake without affecting energy expenditure, leading to preferential accumulation of fat in the abdominal compartment, and especially in the visceral depot,” the researchers wrote. “Our data provide insights into understanding the linkage between insufficient sleep and heightened cardiometabolic risk and have important implications for public health policy and initiatives.”

Sleep, visceral fat and CV risk

In a related editorial, Harold Bays, MD, FOMA, medical director and president of the Louisville Metabolic and Atherosclerosis Research Center and chief science officer for the Obesity Medicine Association, wrote that visceral adipose tissue might be considered a surrogate marker for global fat dysfunction, as it has increased sensitivity to catecholamines, decreased sensitivity to insulin, direct portal access to the liver and greater correlation with cardiometabolic disease.

Treatment for adults with increased visceral fat should include healthful nutrition, physical activity, behavior modification, anti-obesity medications and bariatric surgery, he noted.

“In short, patients may benefit when cardiologists consider evaluating potential sleep disruption and visceral fat accumulation in assessing CVD risk,” Bays wrote.