It is fair to say that obesity is a substantial risk factor for serious illnesses, such as cardiovascular disease and diabetes. Patients are usually advised to reduce their weight by restricting caloric intake (dieting) and increasing the amount of daily exercise. Some experts also believe that lack of sufficient sleep may contribute to obesity. The questions asked by the researchers were: Can sleep and weight reduction be linked? Their results have been published in the Annals of Medicine.[1]
To find out if this was possible they studied 10 otherwise healthy adults who were considered overweight on the basis of their height. They designed their study in a way that ensured that they could keep accurate track of how much the participants were eating, exercising, and sleeping. This means they were confined to a research centre – so no chance of popping out for the small reward from the local shops after a hard nights graft sleeping!
Their food and drink was limited to that provided by the researchers and was designed to produce a steady weight loss. Detailed records were kept of weight, levels of hormones considered important in controlling appetite and weight, and how much hunger participants reported having.
The revealing discovery showed when participants’ sleep was restricted to only 5.5 hours each night, they lost less body fat and more lean body mass than when they slept 8.5 hours—the opposite of what is considered optimal in a calorie-restriction (dieting) program. Participants with restricted sleep also reported feeling more hunger.
Explain to interested patients that middle-aged, overweight patients who slept 8.5 hours burned more fat than those who slept just 5.5 hours.
Note that the study also found that participants in the sleep deprivation group were hungrier and expended less energy to compensate for reduced sleep.
Patients’ energy expenditure, hunger scores, respiratory quotients, body water changes, and body composition were measured. Additionally, the researchers measured metabolic hormone levels, including acylated ghrelin, which acts as a switch to control energy expenditure, hunger, and fat retention, as well as regulate glucose production in the liver.
Regardless of sleep duration, patients lost about 3 kg, but the weight loss came from mostly lean mass in the sleep deprivation group — 2.4 kg versus 1.5 in those who slept for 8.5 hours. Conversely, those who slept for more than 8 hours lost an average of 1.4 kg versus just 0.4 kg of fat loss in the sleep deprivation arm.
Also, patients in the sleep deprivation group were hungrier and 24-hour acylated ghrelin levels increased from an average 73 ng/L pretreatment to 84 ng/L group versus a decline in acylated ghrelin levels (81 ng/L to 75 ng/L) in the normal sleep group, which was statistically significant (P=0.04).
Alternately, resting metabolic rates were significantly higher in the better rested arm and 24-hour plasma epinephrine concentrations were lower, (P=0.005 for both).
There were no significant differences in the measures of the fractional thermic effect of food and 24-hour norepinephrine, cortisol, growth hormone, and thyroid hormone concentrations at the end of study between conditions.
Comment
Managing body mass and assisting with weight control are complex behavioural and nutritional problems. This paper serves to support the role of balanced lifestyle, in which exercise, food selection and recovery play an important role.[2]
References
[1] Nedeltcheva, AV et al. “Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity” Ann Intern Med 2010; 153: 435-441. View Abstract
[2] Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010 Oct 5;153(7):435-41. View Abstract
