A recent study suggests that not getting enough sleep each night may lead to weight gain, which the researchers say is partially caused by your hunger hormones being altered by shuteye deprivation, reports Healthline.
The study by a team at New York’s 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.
The researchers say their findings, published 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.
To understand the connection between sleep and body weight, they combined data from two clinical trials involving 95 adults aged 20 and older.
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 randomised 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 behaviour.
For a smaller group of participants, total daily energy expenditure – the number of calories burned – was measured using a method called “doubly labelled 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 linked to 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 0.45kg compared with when they had adequate sleep.
Waist circumference also increased by about half a centimetre 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 with 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 the weight gain seen with reduced sleep was more than 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 behaviour, which are both important factors in the development of obesity and heart-related diseases.
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 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.
She added that 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 something sweet 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.”
Study details
Prolonged Short Sleep and Its Effect on Body Weight and Composition: A Pooled Analysis of Randomised Trials
Faris Zuraikat, Samantha Scaccia, Justin Cochran et al.
Published in Annals of Internal Medicine on 7 June 2026
Abstract
Background
Insufficient sleep is associated with obesity. However, the causal effect on weight status of chronic, mildly insufficient sleep and its potential variability by gender and menopausal status remain unknown.
Objective
To explore the effect of six weeks of sleep restriction (SR) of 1.5 hours per night on energy balance and body weight regulation.
Design
Pooled analysis of two randomised crossover trials. (ClinicalTrials.gov: NCT02960776 and NCT02835261)
Setting
Outpatient intervention with inpatient and outpatient assessments.
Participants
Adults (n = 95) aged 20 years or older at elevated cardiometabolic risk with habitual sleep of seven or more hours per night.
Intervention
Six weeks of sustained adequate sleep (AS) and SR of 1.5 hours per night separated by a multi-week washout.
Measurements
Outcome measures included adiposity (assessed using magnetic resonance imaging), body weight, waist circumference, and energy balance behaviours and biomarkers.
Results
Sleep duration was reduced by 78.4 minutes (95% CI, −83.5 to −73.3 minutes) per night with SR versus AS. Body weight (0.45 kg [CI, 0.33 to 0.57 kg]), waist circumference (0.52 cm [CI, 0.25 to 0.79 cm]), and whole-body volume (0.56 L [CI, 0.19 to 0.93 L]) were increased with SR relative to AS. Leptin levels were elevated with SR versus AS (2.03 ng/mL [CI, 0.38 to 3.68 ng/mL]). Sedentary time was increased by 17.2 minutes (CI, 11.7 to 22.7 minutes) per day with SR versus AS.
Limitations
The intervention duration may have been too short to identify changes in body composition, power to evaluate individual differences was limited, and effect sizes were modest.
Conclusion
Prolonged exposure to moderately short sleep may lead to weight gain, suggesting that weight management and cardiometabolic disease prevention programmes should consider incorporating sleep strategies to promote AS.
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Too little or too much sleep bad for heart health
Losing sleep increases obesity risk
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