Losing weight is difficult, but keeping it off can be an even greater challenge. New research suggests sleep habits may be one factor that separates people who maintain weight loss from those who regain it.
New research found that people reporting six to eight hours of sleep were less likely to regain weight after a low-carbohydrate diet, although the observational study does not prove that sleep prevented weight regain.
In a real-world study of 294 adults with overweight or obesity who completed a low-carbohydrate diet program, 52% eventually regained weight while 48% maintained their weight loss. Participants who reported sleeping between six and eight hours per night had substantially lower odds of weight regain.
The study, published August 29, 2026, in the European Journal of Clinical Nutrition, also found that having a family history of obesity was associated with a greater likelihood of regaining weight.
The sleep finding is striking, but it requires careful interpretation. Researchers did not assign people to different sleep schedules, and sleep was assessed after the diet rather than experimentally manipulated. The study therefore cannot show that getting six to eight hours of sleep prevents weight regain.
Previous research has nevertheless found similar relationships between insufficient or poor-quality sleep and difficulty maintaining weight loss.
Key Takeaways
- The study included 294 adults with overweight or obesity who had completed a short-term low-carbohydrate diet.
- Participants were followed for an average of about three years.
- Weight regain occurred in 52%, while 48% maintained their weight loss.
- Sleeping six to eight hours per night was associated with substantially lower odds of weight regain.
- A family history of obesity was associated with roughly 2.4 to 2.8 times greater odds of regaining weight.
- Initial weight loss, duration of the low-carb intervention, and exercise frequency were not consistently associated with long-term maintenance.
- The study was observational and does not prove that changing sleep duration will prevent weight regain.
What Did the Researchers Study?
Ruan et al. (2026) examined adults with overweight or obesity who participated in a hospital-based weight-management program involving a low-carbohydrate diet between July 2016 and July 2020.
Participants followed the low-carbohydrate intervention for an average of approximately 6.9 weeks. Researchers later collected information about their weight and lifestyle through structured telephone interviews and questionnaires.
The average follow-up was 36.7 months, or just over three years.
Researchers defined weight regain as gaining back at least 25% of the weight initially lost. Of the 294 participants, 153 regained weight and 141 maintained their weight loss.
The researchers then examined a range of characteristics to determine which were associated with long-term maintenance or regain.
Sleep Stood Out as a Predictor
One of the strongest associations involved sleep.
Participants reporting six to eight hours of sleep per night had substantially lower odds of weight regain. Depending on the statistical model, the odds ratio was approximately 0.15 to 0.16.
An odds ratio of 0.15 might sound as though six to eight hours of sleep reduced the risk of regaining weight by 85%, but that would be too strong a conclusion.
This was not a randomized sleep trial.
People who regularly obtain adequate sleep can differ from short or long sleepers in many ways. Their work schedules, stress, diet, health, medication use, and daily routines may also influence whether they maintain lost weight.
The large association is therefore interesting, but it should not be interpreted as evidence that simply changing someone’s sleep duration to six to eight hours would produce the same effect.
Family History Also Made a Difference
Sleep was not the only factor associated with long-term weight maintenance.
Having a family history of obesity was associated with approximately 2.4 to 2.8 times higher odds of weight regain, depending on the statistical model.
That finding illustrates why maintaining weight loss is unlikely to depend on a single behavior.
Genetic predisposition can influence appetite, energy expenditure, body-fat distribution, and other biological processes involved in body weight. Family history can also capture shared environmental and behavioral influences that are not purely genetic.
The study therefore does not suggest that sleep can override biological susceptibility to obesity. Instead, the findings point toward an interaction between factors people can potentially modify and factors they cannot.
Exercise Did Not Consistently Predict Who Kept the Weight Off
One potentially surprising result was that exercise frequency was not consistently associated with weight-loss maintenance in the study’s statistical models. The amount of weight initially lost and the duration of the low-carbohydrate intervention also were not consistent predictors.
This does not mean exercise is unimportant for weight management.
The study assessed exercise frequency in a real-world observational setting and was not designed to test whether exercise causes better or worse weight maintenance. Exercise intensity, duration, and total activity can also matter beyond simple frequency.
The result is better interpreted as showing that, within this particular group, reported exercise frequency did not clearly distinguish those who regained weight from those who maintained their loss after other factors were considered.
Previous Research Has Also Connected Sleep With Weight Regain
The new findings do not stand alone.
In a 2023 study published in Sleep, Bogh et al. followed 195 adults with obesity who had first lost an average of 13.1 kg during an eight-week low-calorie diet.
Unlike the new study, sleep duration was objectively assessed using wrist-worn accelerometers.
Participants sleeping less than six hours per night at the beginning of the maintenance period regained 5.3 kg during the following year. Poor sleep quality was also associated with greater weight regain.
Bogh et al. (2023) concluded that insufficient sleep predicted poorer weight-loss maintenance, although the analysis still could not establish that short sleep itself caused the regain.
The MedWeight Study Found Sleep Quality May Matter Too
In the MedWeight study, Yannakoulia et al. (2017) compared 528 people who had previously lost substantial weight and either maintained that loss or regained it.
Successful maintainers reported better sleep quality than people who regained weight.
Interestingly, the relationship was not simply about the number of hours slept. Once researchers accounted for sleep quality, sleep duration was no longer independently associated with maintenance status. Better sleep quality remained associated with successful weight maintenance, particularly among men.
That finding provides useful context for the new low-carb study. The relevant factor may not be a precise six-to-eight-hour threshold alone. Sleep quality, consistency, and underlying sleep disorders could also influence the relationship between sleep and body weight.
Why Could Sleep Affect Weight Maintenance?
There are several biologically plausible explanations.
Insufficient sleep can influence appetite, food intake, insulin sensitivity, and the brain’s response to rewarding foods. Experimental sleep-restriction research has also found changes in metabolic processes that could make maintaining an energy deficit more difficult.
There is a behavioral component as well. Someone who is awake for longer has more opportunities to eat, while fatigue may make planned physical activity or food preparation more difficult.
But plausible mechanisms do not prove that sleep caused the difference seen in the new study.
Adequate sleep could partly be a marker of a more stable lifestyle rather than the sole reason participants maintained their weight.
The Study Has Important Limitations
The study was a retrospective observational cohort, not a randomized controlled trial.
Participants came from a hospital-based weight-management program, and the sample of 294 people was relatively small. Follow-up weight and lifestyle information was collected through telephone interviews and questionnaires, meaning some measurements depended on participants accurately recalling and reporting their behavior.
Sleep was not continuously measured using laboratory testing or wearable devices.
There is also the possibility of residual confounding. People sleeping six to eight hours may have differed from other participants in ways the statistical models could not completely capture.
The study therefore identifies predictors and associations rather than establishing that altering those factors will necessarily change someone’s long-term weight trajectory.
What Does the Evidence Actually Tell Us?
The new study adds to evidence suggesting that sleep deserves more attention when researchers examine why some people maintain weight loss while others regain it.
Ruan et al. (2026) found a particularly strong association between six to eight hours of reported nightly sleep and successful long-term weight maintenance after a low-carbohydrate diet. Earlier research has also linked short sleep and poor sleep quality with greater difficulty maintaining lost weight.
The consistency across studies is notable, especially because the 2023 study used objective sleep measurements.
But the evidence still does not establish six to eight hours as a formula for keeping weight off, nor does it show that sleep matters more than diet or exercise.
The more defensible conclusion is that long-term weight maintenance appears to involve more than what people eat. Sleep, biological predisposition, and other lifestyle factors may all contribute to whether initial weight loss lasts.
A randomized study that deliberately improves sleep after weight loss would provide much stronger evidence about whether sleep itself can help prevent weight regain.
References
Ruan, Y., Hu, H., Cheng, Q., et al. (2026). Long-term weight maintenance after a low-carbohydrate diet: A real-world retrospective cohort study. European Journal of Clinical Nutrition. https://doi.org/10.1038/s41430-026-01815-1
Bogh, A. F., Jensen, S. B. K., Juhl, C. R., Janus, C., Sandsdal, R. M., Lundgren, J. R., Noer, M. H., Vu, N. Q., Fiorenza, M., Stallknecht, B. M., Holst, J. J., Madsbad, S., & Torekov, S. S. (2023). Insufficient sleep predicts poor weight loss maintenance after 1 year. Sleep, 46(5), zsac295. https://doi.org/10.1093/sleep/zsac295
Yannakoulia, M., Anastasiou, C. A., Karfopoulou, E., Pehlivanidis, A., Panagiotakos, D. B., & Vgontzas, A. (2017). Sleep quality is associated with weight loss maintenance status: The MedWeight study. Sleep Medicine, 34, 242–245. https://doi.org/10.1016/j.sleep.2017.01.023
