New research has identified a possible way of shedding calories without closely monitoring diets or doing more exercise – simply by spending a little more time in bed, in fact.
In an experiment with 80 overweight adults who usually slept fewer than 6.5 hours a night, adding an average of 1.2 hours of extra shut-eye per night saw a reduction in overall caloric intake by an average of 270 calories a day.
Within two weeks of the experiment, caloric intake – the energy consumed via food and drinks – decreased to be less than the amount of calories burned by the participants, which over the longer term would lead to weight loss.
The research takes the opposite approach to several previous studies that have managed to link not getting enough sleep with putting extra weight on.
“Over the years, we and others have shown that sleep restriction has an effect on appetite regulation that leads to increased food intake, and thus puts you at risk for weight gain over time,” says Esra Tasali, the Director of the University of Chicago Sleep Center.
“More recently, the question that everyone was asking was, ‘Well, if this is what happens with sleep loss, can we extend sleep and reverse some of these adverse outcomes?'”
If this reduction in caloric intake was maintained over three years, it would result in a weight loss of roughly 12 kilograms or 26 pounds over that time, the researchers say.
One of the benefits of the study is that it was carried out in a real-world setting, not the lab. Participants slept in their own beds, using wearables to track their sleep, and went about their days as normal – including what they ate and how much they exercised.
The volunteers used a urine test to track their caloric intake, currently considered the gold standard for measuring daily energy expenditure outside of the lab. It involves drinking water in which the hydrogen and oxygen atoms are replaced with other natural isotopes that are easy to trace.
By comparing the labelled water consumed by the volunteers with non-labelled water from broken down glucose, it’s possible to accurately estimate calories being absorbed away from the lab.
Another notable part of the research was how quickly the group adjusted their sleep schedules – after just a single counseling and advice session led by the research team, overall sleep duration was increased.
“We simply coached each individual on good sleep hygiene, and discussed their own personal sleep environments, providing tailored advice on changes they could make to improve their sleep duration,” says Tasali.
“Importantly, to blind participants to sleep intervention, recruitment materials did not mention sleep intervention, allowing us to capture true habitual sleep patterns at baseline.”
The researchers say that limiting the use of electronic devices before bedtime was one of the key ways of improving sleep behavior in the study. Those participating weren’t told they were taking part in a sleep intervention study when they signed up.
What’s not clear yet is exactly why this is happening, though as noted previous studies have found links between less sleep and an increased appetite, so it’s possible the reverse is happening. In this case, most participants who slept more ate less despite not being told to do so, with some taking in as many as 500 fewer calories per day.
Of course a healthy diet and a decent amount of exercise are important to our health in all kinds of ways, so doctors may not be recommending an extra hour in bed on its own as a route to losing weight. However, proper sleep patterns could play a significant role as part of a broader weight loss program for those with obesity.
“Many people are working hard to find ways to decrease their caloric intake to lose weight – well, just by sleeping more, you may be able to reduce it substantially,” says Tasali.
The research has been published in JAMA Internal Medicine.