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- A new study suggests not getting enough sleep each night may lead to weight gain.
- Those who lost an average of 78 minutes of sleep per night gained almost 1 pound over 6 weeks.
- People who were short on sleep were also found to be more sedentary.
- Sleep deprivation can cause weight gain by altering hunger hormones.
- Getting good quality sleep is an important part of a healthy weight-management strategy.
We all know that not getting enough sleep can leave us feeling groggy and out of sorts, but did you know it might also be quietly adding pounds to your body?
A recent study conducted by researchers at Columbia University found that even a modest reduction in sleep — just an hour and a half less per night for six weeks — can cause noticeable weight gain and changes in the body.
According to the study’s authors, these findings, published on July 7, 2026, in the Annals of Internal Medicine, highlight the role of sleep in managing weight, especially for those already at risk of heart and metabolic diseases.
How researchers examined the relationship between sleep and weight
To understand the connection between sleep and body weight, the researchers combined data from two clinical trials involving 95 adults ages 20 and older.
These participants were all considered at elevated risk for heart and metabolic problems, but typically slept at least seven hours a night before the study began.
The trials used a randomized crossover design, meaning each participant experienced two different sleep conditions over separate six-week periods.
In one condition, called “adequate sleep” (AS), participants maintained their usual sleep habits, averaging seven or more hours of rest each night.
In the other condition, known as “sleep restriction” (SR), participants were asked to delay their bedtime by 1.5 hours, cutting their sleep time by about 90 minutes every night.
To ensure participants followed their sleep schedules, the researchers monitored their sleep using wrist-worn devices called “actigraphs,” which tracked movement and estimated sleep duration.
Participants also kept sleep diaries, and the research team regularly reviewed these to adjust schedules and ensure compliance.
Throughout the study, participants underwent detailed measurements before and after each sleep condition. These included weighing participants, measuring waist circumference, and using magnetic resonance imaging (MRI) to assess body composition, including fat and muscle volumes.
The researchers also collected blood samples to measure hormones related to hunger and energy balance, such as leptin and ghrelin.
In addition, the study tracked daily activity levels using the same wrist devices to see if changes in sleep affected physical activity or sedentary behavior.
For a smaller group of participants, total daily energy expenditure — the number of calories burned — was measured using a method called “doubly labeled water.”
By comparing data collected after adequate sleep and after sleep restriction, the researchers aimed to uncover how a real-world pattern of mild but chronic sleep loss might affect body weight and related health factors.
Sleep restriction was associated with weight gain
When the researchers examined the data, they found that participants who slept about 78 minutes less per night during the sleep restriction phase gained an average of 0.45 kilograms (nearly 1 pound) compared to when they had adequate sleep.
Waist circumference also increased by about half a centimeter during the sleep restriction period, indicating that some of the weight gain was concentrated around the abdomen, which is a known risk factor for heart disease.
MRI scans showed an increase in whole-body volume, but the proportion of body fat versus muscle did not change, suggesting that weight gain was not solely due to fat accumulation.
Looking at the hormones, leptin levels — which signal the body’s energy stores — increased with sleep restriction, consistent with the observed weight gain.
Ghrelin, often called the “hunger hormone,” tended to decrease slightly, though this change was not statistically significant.
There was no change in glucagon-like peptide-1 (GLP-1), another hormone involved in appetite regulation.
Physical activity data revealed that participants spent about 17 more minutes per day being sedentary during the sleep restriction period compared to when they had adequate sleep. However, time spent in moderate-to-vigorous physical activity did not change, which could contribute to weight gain by reducing overall calorie expenditure.
Among the smaller subset of participants who had their total daily energy expenditure measured, no significant difference was found between the two sleep conditions. This suggests that the weight gain seen with reduced sleep was likely due to increased calorie intake and more sedentary time rather than decreased calories burned.
Overall, this study provides strong evidence that losing just a little sleep each night over several weeks can lead to measurable weight gain and increased sedentary behavior, which are both important factors in the development of obesity and heart-related diseases.
Sleep deprivation affects hunger hormones and movement
Jessica Duncan, MD, DABOM, DABA, a board-certified obesity medicine physician and Chief Medical Officer at Ivim Health, who was not involved in the research, said that these findings track with what she sees in her practice.
“If you’re not sleeping restoratively for seven to nine hours, your biology is working against you, and it doesn’t take a big deficit to see it,” she said.
According to Duncan, poor sleep disrupts your hunger hormones, making you crave high-calorie foods that you don’t need. It also impairs insulin sensitivity and raises cortisol, contributing to fat storage around your midsection.
“And it hits your prefrontal cortex, which runs impulse control,” she said. “That’s the real reason you reach for donuts when you’re exhausted. It isn’t weak willpower. It’s a tired brain making worse calls.”
When you don’t get enough sleep, you also move less without even consciously knowing it.
This means less recovery from workouts, less spontaneous movement, and more sitting, according to Duncan.
“You can run on empty for a few days, the way you can swipe a card when you’re short,” she said. “But it compounds, and the body eventually collects, usually as weight gain, more hunger, metabolic dysfunction.”
Good sleep is ‘an important part of a healthy weight-management plan’
“Sleep is not simply a period of rest,” said Destini Moody, RD, CSSD, LD, a board-certified specialist in sports dietetics with Flex Therapist CEUs, who was not involved in the study. “It can affect appetite, energy levels, physical activity, and body composition.
“For this reason, getting enough high-quality sleep should be an important part of a healthy weight-management plan,” she said.
The first step in getting better quality sleep, according to Moody, is following a regular sleep schedule.
“This means going to bed and waking up at approximately the same time each day,” she explained.
A calming bedtime routine can also help. Moody said this might include activities such as reading, taking a warm shower, doing some light stretching, or listening to relaxing music.
“People should limit the use of phones, laptops, and televisions before bed,” she said. “They should also avoid checking work-related emails because this can make it harder to relax.”
Moody additionally advises limiting caffeine, especially later in the day. Also, while drinking alcohol might seem like a good idea, she says consuming it near bedtime could backfire on you.
“Although alcohol may make someone feel sleepy at first, it can reduce sleep quality and increase the chance of waking during the night,” she said.
A dark, quiet, and comfortably cool bedroom can further improve your sleep quality.
Moody said exercise could also help. “However, intense exercise too close to bedtime may make it difficult to fall asleep,” she noted.
When it comes to the amount of sleep, she said most adults need at least seven hours each night. However, the exact amount you need can change throughout your lifetime.
It can also vary from person to person, even within the same age group, per the U.S. Centers for Disease Control and Prevention (CDC).
Finally, if you are having problems falling asleep or staying asleep, or you feel tired despite getting plenty of sleep, Moody said it’s essential to speak with a healthcare professional to rule out or treat any sleep disorders.
