A new study on how getting sufficient sleep affects calorie intake in a real-world setting now proves that more sleep equals weight loss. How? Well, individuals who increased their sleep duration were able to reduce the calorific intake by an average of 270 kcal per day!!
Understanding the underlying causes of obesity and how to prevent it is the best way to fight the obesity epidemic, according to Esra Tasali, MD, Director of the UChicago Sleep Center at the University of Chicago Medicine. “The current obesity epidemic, according to experts, is mostly explained by an increase in caloric intake, rather than lack of exercise,” she said.
In a randomized clinical trial with 80 adults, Tasali and her colleagues at UChicago and the University of Wisconsin-Madison found that young, overweight adults who habitually slept fewer than 6.5 hours a night were able to increase their sleep duration by an average of 1.2 hours per night after a personalized sleep hygiene counselling session. The sleep intervention was intended to extend time in bed duration to 8.5 hours — and the increased sleep duration compared to controls also reduced participants’ overall calorie intake by an average of 270 kcal (calories) per day.
Even though the study did not systematically assess factors that may have influenced sleep behaviour, “limiting the use of electronic devices before bedtime appeared as a key intervention,” said Tasali.
The new study not only examines the effects of sleep extension on calorie intake but, importantly, does so in a real-world setting, with no manipulation or control over participants’ dietary habits. Participants slept in their own beds, tracked their sleep with wearable devices, and otherwise followed their normal lifestyle without any instructions on diet or exercise.
Most other studies on this topic in labs are short-lived, for a couple of days, and food intake is measured by how much participants consume from an offered diet. “In our study, we only manipulated sleep, and had the participants eat whatever they wanted, with no food logging or anything else to track their nutrition by themselves,” she explained
Instead, to objectively track participants’ calorie intake, investigators relied on the “doubly labelled water” method and change in energy stores. This urine-based test involves a person drinking water in which both the hydrogen and oxygen atoms have been replaced with less common, but naturally occurring, stable isotopes that are easy to trace. The use of this technique in humans was pioneered by the study’s senior author Dale A. Schoeller, PhD, Professor Emeritus of Nutritional Sciences at UW-Madison. “This is considered the gold standard for objectively measuring daily energy expenditure in a non-laboratory, real-world setting and it has changed the way human obesity is studied,” said Schoeller.
Overall, individuals who increased their sleep duration were able to reduce their calorie intake by an average of 270 kcal per day – which would translate to roughly 12 kg, of weight loss over three years if the effects were maintained over a long term.
Perhaps the most surprising aspect of the study was the intervention’s simplicity. “We saw that after just a single sleep counselling session, participants could change their bedtime habits enough to lead to an increase in sleep duration,” she said.
Following just a single counselling session, participants increased their average sleep duration by over an hour a night. Despite prescribing no other lifestyle changes, most participants had a large decrease in how much they ate, with some participants eating as many as 500 fewer calories per day.
The subjects were only involved in the study for a total of four weeks, with two weeks for gathering baseline information about sleep and calorie intake, followed by two weeks to monitor the effects of the sleep intervention.