Sleep Loss: Why It’s Making You Fat

Sleep Loss: Why It's Making You Fat

As children, we never think about something as simple as sleep. We wake up in the morning, full of energy, and fall asleep soundly at night, with no problems to waver us from our slumber. However, as we age, many problems get in the way of a good night’s rest. Besides the startling fact that sleep loss is cumulative,1 chronic sleep debt results in vast changes of neurobehavior.2 Furthermore, individuals that believe they ‘adapt’ to sleep loss are only fooling themselves.3 Deficits in daytime performance due to sleep loss are experienced universally and associated with a significant social, financial, and human cost.4 If you sleep 6 hours or less per night, chronically, it is the same as staying awake for 2 days, neurologically.5 And on top of all that, sleep loss helps makes you fat.6

So what is going on in your body, when you are sleep deprived? And how does this stream of biochemical changes help to make you fat? To start with, research shows sleep deprivation has profound metabolic and cardiovascular implications.7 Hormonally and biochemically, we point the finger of blame at two suspects: leptin and ghrelin. These two hormones have a profound effect on appetite control.8 And these two hormones are both greatly affected by sleep loss.9,10

In a single night of sleep loss, men experience an increase in levels of ghrelin, which is usually referred to as your ‘hunger’ hormone.11 Your ‘satiety’ hormone, leptin, by contrast, is decreased after sleep loss.12 So you will be hungrier, and less satisfied when you eat. Not only that, but your nucleus accumbens, which is your brain’s pleasure center, and a whole host of other brain areas, such as the putamen, thalamus, insula, and prefrontal cortex, are more susceptible to food reward, when sleep deprived.13

Neurons that release serotonin, are modified via carbohydrate ingestion.14 Since 5-Hydroxytryptamine (5-HT), or serotonin, is a vital neurotransmitter, which helps to regulate sleep,15 the biochemical parallels between diet, specifically carbohydrate intake, and sleep, can be further filled in. The neurological differences between a meal filled with protein, and a meal filled with carbohydrate, are vast and surprising. Your brain actually utilizes the food-induced changes in brain serotonin in order to make choices about what to eat.16 You can begin to see how this would also cause you to crave carbohydrates, especially when sleep deprived.17 Your brain is receiving less of a satiety signal, more of a hunger signal, is fatigued, and carbohydrates provide a quick boost of energy.18 This then disrupts your next meal, and possibly your sleep.19

Furthermore, studies have shown that glucagon-like peptide 1, which is a hormone that promotes satiety, is delayed in doing its job, when sleep deprived.20 This is yet another biochemical mechanism by which you can overeat, when you’re not well rested. Add to that list, neuropeptide Y. Neuropeptide Y normally expresses itself in order to increase food intake.21 When sleep deprived, this neuropeptide expression rapidly increases,22 effectively telling your brain to eat more.

More and more studies are showing the link between sleep deprivation and obesity.23 There are even interesting studies relating nighttime eating and weight gain.24 A simple search for the terms ‘sleep and obesity’ yields over 6000 results in one scientific database alone.5 The link is very clear, and many of the biochemical mechanisms are outlined above.

A real food based approach, like The Paleo Diet, not only provides a plethora of nutrients, minerals and vitamins, but helps to stabilize blood sugar levels, and regulate hormones.26 This not only means that you’ll sleep better, but, as a result, it will be much easier to stay lean, fit and healthy.

Sleep | The Paleo DietSleep Loss: The Universal Problem We Face



1. Cohen DA, Wang W, Wyatt JK, et al. Uncovering residual effects of chronic sleep loss on human performance. Sci Transl Med. 2010;2(14):14ra3.

2. Dinges DF, Pack F, Williams K, et al. Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4-5 hours per night. Sleep. 1997;20(4):267-77.

3. Cohen DA, Wang W, Wyatt JK, et al. Uncovering residual effects of chronic sleep loss on human performance. Sci Transl Med. 2010;2(14):14ra3.

4. Durmer JS, Dinges DF. Neurocognitive consequences of sleep deprivation. Semin Neurol. 2005;25(1):117-29.

5. Van dongen HP, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep. 2003;26(2):117-26.

6. Jean-louis G, Williams NJ, Sarpong D, et al. Associations between inadequate sleep and obesity in the US adult population: analysis of the national health interview survey (1977-2009). BMC Public Health. 2014;14:290.

7. Sharma S, Kavuru M. Sleep and metabolism: an overview. Int J Endocrinol. 2010;2010

8. Klok MD, Jakobsdottir S, Drent ML. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obes Rev. 2007;8(1):21-34.

9. Knutson KL. Impact of sleep and sleep loss on glucose homeostasis and appetite regulation. Sleep Med Clin. 2007;2(2):187-197.

10. Motivala SJ, Tomiyama AJ, Ziegler M, Khandrika S, Irwin MR. Nocturnal levels of ghrelin and leptin and sleep in chronic insomnia. Psychoneuroendocrinology. 2009;34(4):540-5.

11. Schmid SM, Hallschmid M, Jauch-chara K, Born J, Schultes B. A single night of sleep deprivation increases ghrelin levels and feelings of hunger in normal-weight healthy men. J Sleep Res. 2008;17(3):331-4.

12. Taheri S, Lin L, Austin D, Young T, Mignot E. Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index. PLoS Med. 2004;1(3):e62.

13. St-onge MP, Mcreynolds A, Trivedi ZB, Roberts AL, Sy M, Hirsch J. Sleep restriction leads to increased activation of brain regions sensitive to food stimuli. Am J Clin Nutr. 2012;95(4):818-24.

14. Wurtman RJ, Wurtman JJ. Brain serotonin, carbohydrate-craving, obesity and depression. Obes Res. 1995;3 Suppl 4:477S-480S.

15. Jing F, Zhang J. Metabolic Kinetics of 5-Hydroxytryptamine and the Research Targets of Functional Gastrointestinal Disorders. Dig Dis Sci. 2014;

16. Wurtman RJ, Wurtman JJ. Carbohydrate craving, obesity and brain serotonin. Appetite. 1986;7 Suppl:99-103.

17. Nedeltcheva AV, Kilkus JM, Imperial J, Kasza K, Schoeller DA, Penev PD. Sleep curtailment is accompanied by increased intake of calories from snacks. Am J Clin Nutr. 2009;89(1):126-33.

18. Weiss A, Xu F, Storfer-isser A, Thomas A, Ievers-landis CE, Redline S. The association of sleep duration with adolescents’ fat and carbohydrate consumption. Sleep. 2010;33(9):1201-9.

19. Ip M, Mokhlesi B. Sleep and Glucose Intolerance/Diabetes Mellitus. Sleep Med Clin. 2007;2(1):19-29.

20. Benedict C, Barclay JL, Ott V, Oster H, Hallschmid M. Acute sleep deprivation delays the glucagon-like peptide 1 peak response to breakfast in healthy men. Nutr Diabetes. 2013;3:e78.

21. Ramos EJ, Meguid MM, Campos AC, Coelho JC. Neuropeptide Y, alpha-melanocyte-stimulating hormone, and monoamines in food intake regulation. Nutrition. 2005;21(2):269-79.

22. Koban M, Le WW, Hoffman GE. Changes in hypothalamic corticotropin-releasing hormone, neuropeptide Y, and proopiomelanocortin gene expression during chronic rapid eye movement sleep deprivation of rats. Endocrinology. 2006;147(1):421-31.

23. Spivey A. Lose sleep, gain weight: another piece of the obesity puzzle. Environ Health Perspect. 2010;118(1):A28-33.

24. Gluck ME, Venti CA, Salbe AD, Krakoff J. Nighttime eating: commonly observed and related to weight gain in an inpatient food intake study. Am J Clin Nutr. 2008;88(4):900-5.

25. sleep and obesity – PubMed – NCBI. (n.d.). Retrieved from //

26. Frassetto LA, Schloetter M, Mietus-synder M, Morris RC, Sebastian A. Metabolic and physiologic improvements from consuming a paleolithic, hunter-gatherer type diet. Eur J Clin Nutr. 2009;63(8):947-55.

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  21. Hello, I want to sleep for longer but I wake up in approx. 4-5 hours after I go to bed. I wake up refreshed. in approx. 2 hours I am tired. my eyes hurt.
    I go to bed before 10pm.

    I don’t think I am stressed – I asked myself the question but could not find any answer.

    I do eat what I think is 100% paleo. I am allergic to lots of things and I have found the paleo diet great.

    any suggestions?

  22. Hi Casey!

    Great article! Thank you! I was wondering… The app your talking about in your radio interview, is it available for apple products? I couldn’t seem find it in the App Store.

    Thank you for your time!


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  24. Great article, Casey! And to add to it, there are strong links between obesity and mood disorders such as MDD (Major Depressive Disorder) and anxiety. Thus, a diet high in processed carbs and sleep loss and mood disorders could all be part of a vicious circle.

    • Based on my own experience, I wholeheartedly agree with that. There is also a social/political dimension to it: it becomes obvious why many people who have to work two jobs to make ends meet and whose job situation is generally precarious tend to overeat and have a shorter life-span. Let alone the fact that they neither have the time or money to eat a truly healthy diet. This is the “bigger” vicious circle. Ever since I quit my stressful yet boring job, my sleeping, eating and mood problems have greatly improved. But not everybody can afford to do so.

      • Christina,

        This is spot on.

        An unfortunate reality of the current world we live in, is overpopulation.

        Many of these issues could be solved via less people, but obviously that is not a realistic solution. You can begin to see the strain our food resources, fuel resources, economic resources et. al. are going to be taking in the coming years.

        Casey Thaler
        B.A., NASM-CPT, FNS
        Eat Clean, Train Clean®:
        Eat Real Food, Change Your Life™

    • Aaron,

      Once again, humbled by your readership. I agree that there is large overlap between all of the conditions mentioned. A particularly intriguing topic for me is metabolic syndrome in the brain:

      Figure 8 is particularly interesting. I also was asked to speak on this article on the radio in London, Ontario, Canada. If anyone is interested in listening, I was able to cover a few topics not in the article:

      Casey Thaler
      B.A., NASM-CPT, FNS
      Eat Clean, Train Clean®:
      Eat Real Food, Change Your Life™

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