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Sleep Deprivation and Weight Gain: Leptin, Ghrelin and Appetite

Does lack of sleep really promote weight gain? Experimental studies show that a few nights of shortened sleep lower leptin, raise ghrelin, increase hunger and appetite for carbohydrate-rich foods, and worsen tissue sensitivity to insulin. In one controlled-diet study, lack of sleep made people on a weight-loss diet lose less fat and more fat-free mass. We discuss exactly what was shown, what the limitations of these studies are and what follows in practice.

MNMichał NowakOctober 17, 202612 min read
Table of contents

TL;DR — key takeaways

Does lack of sleep cause weight gain? The short answer

The answer in brief

Yes, experimental studies indicate that shortened sleep promotes weight gain. The mechanism has several layers: after a few days of sleep loss, leptin (the satiety hormone) falls, ghrelin (the hunger hormone) rises, appetite increases especially for high-calorie foods, and the body, eating more, particularly late in the evening and at night, overshoots its energy needs. On top of this comes poorer sensitivity to insulin. This does not mean sleep is the only factor in weight gain, but that it is an important, modifiable piece of the puzzle.

Most of the strongest evidence comes from short laboratory studies in small groups of healthy people whose sleep was artificially shortened. This is a good way to show causality but a poorer way to estimate the size of the effect in everyday life. That is why in this article we separate what has been shown under controlled conditions from what is still only a hypothesis or inference from observational studies.

You will find a broader discussion of appetite hormones in our entry on leptin and ghrelin, and the effects of sleep loss on the whole body in the entry on sleep deprivation. Here we focus on one question: why does shorter sleep usually mean greater hunger, and what follows for weight.

Leptin and ghrelin: what changes after just two nights?

Leptin is secreted by fat tissue and informs the brain about energy stores, suppressing appetite. Ghrelin, produced mainly in the stomach, acts the opposite way: it rises before a meal and stimulates hunger. In the 2000s a group of researchers at the University of Chicago showed that just two nights of shortened sleep change the balance of these hormones.

Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite

Moderate evidence

Spiegel K, Tasali E, Penev P, Van Cauter E · Annals of Internal Medicine · 2004

A randomised crossover study of 12 healthy men (mean age 22, BMI 23.6 kg/m²) under controlled diet and activity. After 2 days of sleep restriction, compared with 2 days of sleep extension, mean leptin was 18% lower (p=0.04), ghrelin 28% higher (p<0.04), hunger rose by 24% (p<0.01) and appetite by 23% (p=0.01), especially for calorie-dense, carbohydrate-rich foods (an increase of 33-45%; p=0.02). The authors note limitations: only 12 young men and no measurement of energy expenditure.

View study

The direction of the changes is unambiguous, but the scale must be kept in mind: two days in 12 young healthy men. It is not known from this how large the effect is in women, older people or people with overweight, or whether it persists with months of sleep loss. Lower leptin is also not the same as the 'leptin resistance' seen in obesity; here we are talking about an acute, reversible hormonal change.

More eating, especially at night: data from five nights of sleep loss

Hormonal changes are only one part of the story. The other is behaviour: whoever stays awake longer has more opportunities and reasons to eat. A study conducted in an inpatient setting made it possible to measure energy expenditure, intake and weight gain at the same time.

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Moderate evidence

Markwald RR, Melanson EL, Smith MR, Higgins J, Perreault L, Eckel RH, Wright KP Jr · Proceedings of the National Academy of Sciences · 2013

A 14- to 15-day inpatient study of 16 adults assessing the effects of 5 days of insufficient sleep (equivalent to a work week) compared with adequate sleep. Insufficient sleep increased total daily energy expenditure by about 5%, but energy intake, especially at night after dinner, exceeded energy needs. This led to a weight gain of 0.82 ± 0.47 kg despite changes in ghrelin, leptin and peptide YY that signalled excess energy stores. In women, insufficient sleep reduced dietary restraint and led to weight gain, whereas in men not to the same degree. Returning to adequate sleep reduced energy intake. The authors suggest that increased eating is a physiological adaptation to longer wakefulness, but easily available food leads to overshooting.

View study

This result completes the hormonal picture in an important way. A sleep-deprived body does use a little more energy (longer wakefulness costs), but eats far more than that difference, especially in the evening and at night. The laboratory data fit everyday intuition: night-time snacking during sleep loss tends to be dominated by highly processed foods.

Insulin sensitivity: what does sleep loss do to fat cells?

The third layer is glucose metabolism. Sleep loss worsens tissue sensitivity to insulin, so the body needs more insulin to achieve the same effect. High insulin favours fat storage and hinders its mobilisation. We write more about this phenomenon in the entry on insulin resistance.

Impaired insulin signaling in human adipocytes after experimental sleep restriction: a randomized, crossover study

Early-stage evidence

Broussard JL, Ehrmann DA, Van Cauter E et al. · Annals of Internal Medicine · 2012

A randomised crossover study of 7 healthy adults (1 woman, 6 men; mean age 23.7; BMI 22.8 kg/m²) who spent 4 days with 4.5 or 8.5 hours in bed under controlled conditions. Adipocytes taken from subcutaneous fat after restricted sleep needed almost 3-fold higher insulin concentration (0.71 nM vs 0.24 nM; p=0.01) to reach the half-maximal response in the signalling pathway, and the total response was 30% lower. In parallel, whole-body insulin sensitivity fell (p=0.02). The authors stress limitations: a single-centre study with a very small sample.

View study

This study has mechanistic value: it shows that sleep restriction changes the behaviour of fat cells at the level of insulin signalling. But the sample was seven people and the effect covered four days. One must not conclude that a few short nights 'ruin metabolism permanently'; the results point rather to rapid, probably reversible changes.

Weight-loss diet and sleep loss: why does a calorie deficit go to waste?

For people on a diet the most important question is whether sleep loss weakens the effects of weight loss. The answer comes from a study in which the same people went through two courses of the same diet: once with the opportunity for long sleep, once with shortened sleep.

Insufficient sleep undermines dietary efforts to reduce adiposity

Moderate evidence

Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD · Annals of Internal Medicine · 2010

A randomised crossover study of 10 overweight adults (3 women, 7 men; mean age 41; BMI 27.4 kg/m²) who followed moderate calorie restriction for 14 days with 8.5 or 5.5 hours of nighttime sleep opportunity. Shortened sleep decreased the proportion of weight lost as fat by 55% (1.4 vs 0.6 kg at 8.5 vs 5.5 hours; p=0.043) and increased the loss of fat-free body mass by 60% (1.5 vs 2.4 kg; p=0.002). This was accompanied by increased hunger and a shift in metabolism toward less fat oxidation. The authors note limitations: short duration and small sample.

View study

The conclusion has major practical importance: with the same calorie deficit, sleep-deprived people lost more muscle and less fat, and were hungrier. This does not mean that it is impossible to lose weight without sleep, but that a diet combined with sleep loss is less effective and harder to sustain. The same logic is reflected in the data on sleep extension, discussed next.

And if you sleep longer? A study from everyday life

If shortening sleep increases intake, the opposite intervention should reduce it. This was examined in everyday life, without an imposed diet or activity, using objective methods of measuring energy.

Effect of Sleep Extension on Objectively Assessed Energy Intake Among Adults With Overweight in Real-life Settings: A Randomized Clinical Trial

Strong evidence

Tasali E, Wroblewski K, Kahn E, Kilkus J, Schoeller DA · JAMA Internal Medicine · 2022

A single-centre randomised trial (2014-2020) of 80 adults aged 21-40 with overweight (BMI 25.0-29.9) and habitual sleep shorter than 6.5 hours a night. After 2 weeks of observation, participants were assigned to a single sleep hygiene counselling session aimed at extending time in bed to 8.5 hours or to continue their habitual sleep. Sleep lengthened by about 1.2 hours a night (95% CI 1.0-1.4). Energy intake, assessed objectively with doubly labeled water and changes in energy stores, fell in the sleep extension group by 270 kcal/day relative to control (95% CI -393 to -147; p<0.001). Energy expenditure did not change significantly, resulting in weight reduction relative to the control group. The change in sleep length correlated inversely with the change in energy intake (r = -0.41).

View study

This is one of the strongest studies on the topic: randomised, in real life, with objective energy measurement. Note, however, the narrow group: young adults with mild overweight who clearly slept too little. The results cannot be automatically transferred to people who already sleep 7-8 hours, or to people with obesity or older adults. It is also worth remembering that participants changed their own habits; without support, sustaining longer sleep over time can be hard.

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What this means in practice: a checklist

How to use what we know about the link between sleep and appetite

  • Aim for 7-9 hours of sleep at night; if you now sleep less than 6.5 hours, even 30-60 minutes longer may make a difference, but do not promise yourself a change in energy balance overnight
  • Keep fixed sleep and wake times; an irregular rhythm promotes snacking in the evening and at night
  • If you are dieting, do not plan a deep calorie deficit while also sleeping too little; under controlled conditions it ends in loss of muscle and more hunger
  • In the evening do not keep highly processed foods within reach; they dominate night eating in sleep-deprived people
  • Include protein and fibre at dinner and plan the last meal 2-3 hours before bed, which reduces the urge to snack at night
  • Get outside into daylight in the morning and move during the day; this supports both the circadian rhythm and appetite regulation
  • Limit caffeine to the first half of the day and alcohol to a minimum; both impair sleep quality
  • Investigate the causes of short sleep (snoring, apnea, insomnia, shift work) instead of forcing longer time in bed
  • If you eat a lot at night and feel a loss of control, talk to a doctor or clinical dietitian: it may be night eating syndrome and not sleep loss alone

Myth or fact: does short sleep burn more calories?

Myth

Since I stay awake longer, I burn more calories, so cutting sleep helps me lose weight.

Fact

True, in an inpatient study 5 days of insufficient sleep raised daily energy expenditure by about 5%, but energy intake (especially after dinner) exceeded needs, which translated into a weight gain of about 0.8 kg. In addition, in a study on a reduction diet, short sleep cut the share of fat in the weight lost by 55%. The net balance therefore argues against shortening sleep as a weight-loss strategy.

Do not cut sleep to 'have more time for training'

Training will not make up for the effects of sleep loss if it comes at the expense of sleep. From the standpoint of both weight and muscle recovery, it is better to keep sleep and shorten the workout than the other way round.

When to see a doctor

Signs that call for a consultation

  • Rapid, unexplained weight gain (for example several kilograms over months) with chronic fatigue, feeling cold, swelling or dry skin: worth checking the thyroid
  • Loud snoring, breathing pauses, morning headaches and daytime sleepiness: sleep apnea both promotes weight gain and is worsened by it
  • Excessive thirst, frequent urination, blurred vision or skin infections (suspected diabetes)
  • Binge eating, loss of control over eating, night eating combined with guilt
  • Chronic sleep loss despite the opportunity to sleep, lasting more than 3 months, or insomnia with low mood
  • Weight gain with menstrual disorders, excess hair growth or skin discoloration (hormonal evaluation)

Limitations and summary

What these studies do not settle

The experimental studies covered from 7 to 16 people (apart from the randomised trial with 80 participants) and lasted from a few days to two weeks, so it is not known how long the described effects last or how large they are in people of different ages, women, people with obesity or after illness. Hormone level measurements reflect a momentary state, and their link to long-term weight gain is not certain. The results of observational studies in which short sleep is linked to higher BMI are exposed to confounding. The article is not for treating obesity and does not replace the advice of a doctor or dietitian.

StudyParticipants and durationMain result
Spiegel 200412 men, 2 days of shortened sleepLeptin -18%, ghrelin +28%, hunger +24%, appetite +23%
Markwald 201316 adults, 5 days of insufficient sleepExpenditure +5%, but excess calories; weight gain about 0.8 kg
Broussard 20127 adults, 4 days of 4.5 hours' sleepAbout 3-fold lower insulin sensitivity of adipocytes
Nedeltcheva 201010 people with overweight, 14 days of dietFat share of weight lost -55% at 5.5 hours of sleep
Tasali 202280 people, RCT, about 1.2 h longer sleepEnergy intake -270 kcal/day

Sleep loss and weight gain: key study results

Our editorial recommendation

Sleep is one of the few interventions that at the same time lowers hunger, improves insulin sensitivity and helps lose fat rather than muscle, and costs nothing but time. It is not a miracle cure for obesity and will not replace diet or physical activity, but it is worth treating as the foundation on which those efforts rest. If you keep dieting without results and sleep less than 6.5 hours, start with sleep, and only then with further calorie cuts.

You cannot beat hunger with willpower if for several nights your hormones have been telling your brain that it is hungry. Sleep first, count calories afterwards.

Michał Nowak, VitMode editorial team

Frequently asked questions

Experimental studies indicate it can. In an inpatient study 5 days of insufficient sleep raised daily energy expenditure by about 5%, but energy intake exceeded needs and participants gained 0.82 kg on average. These are short-term results in a small group, so the size of the effect over the long term is not known.

In a study of 12 young men, 2 days of restricted sleep lowered mean leptin by 18%, raised ghrelin by 28%, and increased hunger by 24% and appetite by 23%, especially for calorie-dense, carbohydrate-rich foods. The changes were reversible on returning to normal sleep.

After sleep restriction hunger and appetite rise, especially for calorie-dense, carbohydrate-rich foods (a 33-45% increase in the Spiegel et al. study). On top of this, longer time awake gives more opportunities to eat, particularly after dinner. This comes from hormones and behaviour, not from a lack of willpower.

In young adults with mild overweight who slept less than 6.5 hours, extending sleep by about 1.2 hours reduced energy intake by 270 kcal a day in a randomised trial (Tasali et al., 2022) and resulted in weight reduction relative to the control group. The results concern a specific group and do not mean that everyone who starts sleeping longer will lose weight.

Yes, in a small crossover study of 10 people with overweight. On the same low-calorie diet, with 5.5 hours of sleep the share of fat in the weight lost was 55% lower than with 8.5 hours, and the loss of fat-free mass was 60% greater. This was accompanied by greater hunger.

In a small experimental study, four days of 4.5 hours of sleep reduced the insulin sensitivity of fat cells almost threefold and lowered whole-body sensitivity. This demonstrates a mechanism but does not assess the long-term risk of diabetes; that question needs other studies.

There is no single number. Recommendations for adults fall in the range of 7-9 hours, and studies indicate that chronically sleeping less than about 6.5 hours promotes greater energy intake. Individual need depends on age, health and lifestyle; how you feel during the day also matters.

Sources

MN

Michał Nowak

MSc in Clinical Dietetics, certified sports-nutrition coach

Michał started out as a long-distance runner, before an injury forced him to rethink his career. Looking for a faster way back into shape, he discovered sports nutrition and never left — fascinated by the gap between the research and what "everyone knows" at the gym. He completed a degree in clinical dietetics, earned a sports-nutrition coaching certification, and ran his own practice for several years before joining VitMode. His writing keeps returning to one theme: a supplement won't replace the basics, but the right one, at the right time, makes a real difference — and that's the difference he tries to describe precisely, with citations instead of slogans. He still runs, though these days, as he puts it, purely for the fun of it.

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Comments (2)

  • KW

    Kasia W. 2 weeks ago

    Very clearly explained, especially the interactions section — I hadn't seen it laid out this well anywhere else.

  • MT

    Marek T. a month ago

    Are you planning to update this with the newest study from this year? I saw an interesting meta-analysis.