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According to a new study, sleeping more may aid weight loss. Sjale/Getty Images
  • One of the primary causes of obesity is consuming more calories than necessary.
  • Laboratory studies have found that people with significant sleep restriction are likely to consume more calories than they would without sleep restriction.
  • In a new study, researchers report that participants with overweight who were not getting enough sleep reduced their daily calorie intake after receiving sleep training.

Scientists have recently investigated the potential role of sleep education in weight loss programs.

Their results, which appear in the journal JAMA Network, lay the groundwork for further research to see if the findings are generalizable and hold true over longer periods.

According to the World Health Organization (WHO), rates of obesity have almost tripled since 1975.

In the United States, 42.4% of people had obesity in 2017–2018, up from 30.5% in 1999–2000.

Obesity is linked with many leading, preventable causes of death, including stroke, heart disease, type 2 diabetes, and some types of cancer.

The primary cause of obesity is consuming more calories than are used.

The WHO points out that globally, diets are containing more energy-dense foods that are high in sugar and fat. At the same time, people have tended to become more sedentary, meaning they are burning fewer calories.

Meanwhile, many social, economic, and environmental factors contribute to people developing overweight and obesity.

Researchers believe that not getting enough sleep is a risk factor. In experimental laboratory studies, scientists have shown that when someone is sleep-deprived, they are more likely to increase their calorie intake.

However, until now, little research had investigated this effect in real-life settings.

In the present study, the researchers set out to investigate the relationship between sleep duration and calorie intake in a real-life setting.

Their randomized controlled trial had 80 adult participants aged 21–40. They had overweight and were typically sleeping less than 6.5 hours per night.

The scientists recorded the participants’ sleep using activity-tracking watches for 2 weeks to gather baseline information.

They then split the participants into two groups. The first continued with normal sleeping patterns for 2 weeks and functioned as a control group. In the second group, each person received one session of individual sleep hygiene counseling and a personalized sleep-wake schedule to follow for 2 weeks. The aim was to increase their sleep to 8.5 hours each night.

To track the two groups’ energy intake, the researchers used the doubly labeled water method. Dr. Esra Tasali, director of the Sleep Research Center at the University of Chicago and corresponding author of the study, explained to Medical News Today how this works:

“The doubly labeled water method is a urine-based test that involves a person drinking a harmless water in which both the hydrogen and oxygen atoms are replaced with less common, but naturally occurring, stable isotopes that are easy to trace.”

“This technique was developed in the 1950s in animals and applied to humans for the first time in 1982 by my colleague and [co-]author of our paper, Dale Schoeller. Dale pioneered this work.”

Dr. Tasali explained that this is “the gold standard method to objectively track energy expenditure in real-world conditions, and it has revolutionized how obesity is studied. This method allowed us to track and quantify energy intake without participants food logging — or anything else — to track their nutrition.”

The researchers found that the participants who received sleep hygiene counseling reduced their energy intake by an average of 270 calories each day, compared with the control group.

They also increased their sleep by more than 1 hour, on average, each night.

“According to strong dynamic prediction models, […] if healthy sleep habits are maintained, we would predict a 12-kilogram (26-pound) weight loss over 3 years.”

– Dr. Esra Tasali

Dr. Tasali said that while the study did not aim to determine how reducing sleep deprivation had this effect, previous research provided some clues.

“Our study did not investigate mechanisms per se, but potential explanations based on prior work on sleep loss point toward certain pathways.”

These, she explained, could include “alterations in hunger and appetite-regulating hormones. Ghrelin, for example, decreases and you feel less hungry.”

Dr. Tasali also suggested that changes in brain regions that regulate appetite or reward centers in the brain might cause us to eat less. Additionally, circadian factors may play a role.

Dr. Lu Qi, director of the Tulane University Obesity Research Center — who was not involved in the study — told MNT that the findings were significant:

“Even [though] sleep restriction has been related to a higher risk of obesity and higher energy intakes in a body of observational studies, the evidence linking sleep duration to energy intakes from randomized clinical trials is scarce.”

“Randomized clinical trials are considered the gold-standard approach to studying causal relationships. In this regard, the findings from this study are important.”

Dr. Qi added that there could be several causes of the findings:

“Sleeping longer may affect the secretion of appetite regulatory hormones, such as leptin and ghrelin, which may inhibit intakes of foods and energy. In addition, there are studies suggesting that sleep restriction may change the brain activity related to food reward, and shorter sleep provides greater reward of food. Moreover, sleeping more reduces the time for eating.”

In an invited commentary on the new research, Dr. Mark R. Rosekind, from the Johns Hopkins Center for Injury Research and Policy, and colleagues point out some areas of the study that could be developed in future research.

“Participants in the study had overweight and were sleep-deprived at baseline, raising the question of whether the findings are generalizable to other groups.”

“How sleep extension would work in people who are not already sleep deprived or those with normal weight cannot be determined from this study. Whether the outcomes would be sustained, enhanced, or diminished over time is also not known,” the authors acknowledge.

Dr. Qi agreed: “The intervention is short-term and small-sized; the participants are relatively young and with a higher body mass index. Therefore, further larger, long-term intervention studies are needed in more general populations.”

According to Dr. Tasali, “The next step would be to add sleep extension intervention to rigorous randomized controlled weight loss trials to see how it affects diet and to find out the effects sleep extension has on weight in the long term.”