Hormones of Obesity: Ghrelin

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Ghrelin: The Gremlin of Hunger Hormones

If you talk to the average American, they have heard of adrenalin, insulin, and cortisol.  If you mention ghrelin, they will probably think it was a corny 1980s film about little creatures that you should not feed at night or give water.  This one is almost as sinister and is definitely one of the reasons Americans are so fat.  

What is the function of  Ghrelin?

Ghrelin is an appetite stimulator.  The hormone is released primarily in the stomach and evidence indicats it signals the brain to increase hunger.  So. ghrelin is a participant in regulating the complex process of energy homeostasis by adjusting energy input through hunger signals between the brain and the stomach.  Although, ghrelin is not a newly discovered hormone, we are just starting to understand how it works.  Ghrelin levels increase when you under eat and levels are low when you overeat.  Of note, ghrelin levels have been found to increase in patients with anorexia nervosa and decrease in those who are obese.  There is conflicting evidence, but is believed that the stretch of the stomach reduces the release of ghrelin.  

Ghrelin Stimulation
Ghrelin Stimulation

Researchers have suggested that ghrelin levels play a big role in determining how quickly hunger comes back after we eat. Normally, ghrelin levels go up dramatically before you eat; this signals hunger. They then go down for about three hours after a meal.  

What is Ghrelin?

Ghrelin is a polypeptide hormone that is produced mostly in the stomach and small intestine. It has been called the “hunger hormone” because of its role in controlling appetite, but even though it has other functions, we are mostly interested in the appetite-related function.  

Ghrelin the Zero
Ghrelin the Zero

How Does Ghrelin Work?

Ghrelin serves many purposes, but the one most commonly talked about is its ability to stimulate increased appetite, causing an individual to digest more food and store more fat.  In fact, when given artificially, both body mass and body fat increase​1​,​2​.  Not only does it increase weight and body fat, but it also increases feeding activity and the level of feeding is dose-dependent​3​,​4​.  The levels of ghrelin are the highest right before a meal and lowest right after​5​.  The hormone is released by the stomach when it is empty to signal the hypothalamus, the part of the brain that controls appetite, and also may act on regions of the brain that control reward processing.

Ghrelin Activity
Ghrelin Activity

The interesting thing about ghrelin is that sleep has an effect on ghrelin levels.  As sleep levels increase, ghrelin and obesity levels decrease​6​,​7​.  The key point is that obesity decreases with adequate sleep and ghrelin levels may have something to do with it.  

Problems Associated with Ghrelin

Because ghrelin affects appetite, it can impact weight loss, especially when someone diets.  When someone is strictly controlling calories, ghrelin levels increase.  This causes the rebound of the pounds lost that happens right after a diet for many people. People who struggle with anorexia nervosa may also have high ghrelin levels, which occur because of the body’s natural response to starvation.  This may play a part in dieters regaining weight.  The elevation in ghrelin and weight gain is less in those that have a slower weight loss.  I would take this as an indication for moderation and gradual weight loss. 

How can I naturally control ghrelin?

Performance Triad
Performance Triad: A program pushed by the US Army has it right.  
  • Are ghrelin blocker products an effective way to control hunger?
    1. Although, the studies are mixed.  I recommend walking.  A good study those that brisk walking reduces ghrelin​8​,​9​.  
    2. Burst training on a spin bike.  This will lower ghrelin​10​,​11​.  
    3. Avoid high-intensity training which lowers leptin​12​.  High intensity may both lower leptin levels but also lower the receptor for leptin which may be a double whammy for weight loss.  
    4. Adequate sleep​6​.
    5. Stress management and behavioral health intervention lower ghrelin​13​.  
    6. Exercise on an empty stomach​14​.  
    7. Add protein to every meal​15​,​16​.  The bottom line is that protein suppresses ghrelin and controls appetite.  
    8. Avoid sugary and high fructose corn syrup.  Both will increase ghrelin and your appetite​17​,​18​.   
  • Are my ghrelin levels responsible for my weight struggle?
    • The simple answer is yes.  It is not that simple but ti does contribute to weight gain.  
  • How can I lose weight without impacting ghrelin levels negatively?
    • The key thing to me is eating right (low sugar diet), lowering stress, exercising, and getting adequate sleep.  

Ghrelin Research:


  1. 1.
    Tschöp M, Smiley D, Heiman M. Ghrelin induces adiposity in rodents. Nature. 2000;407(6806):908-913. [PubMed]
  2. 2.
    Chebani Y, Marion C, Zizzari P, et al. Enhanced responsiveness of Ghsr Q343X rats to ghrelin results in enhanced adiposity without increased appetite. Sci Signal. 2016;9(424):ra39. [PubMed]
  3. 3.
    Wren A, Small C, Ward H, et al. The novel hypothalamic peptide ghrelin stimulates food intake and growth hormone secretion. Endocrinology. 2000;141(11):4325-4328. [PubMed]
  4. 4.
    Wren A, Seal L, Cohen M, et al. Ghrelin enhances appetite and increases food intake in humans. J Clin Endocrinol Metab. 2001;86(12):5992. [PubMed]
  5. 5.
    Tolle V, Bassant M, Zizzari P, et al. Ultradian rhythmicity of ghrelin secretion in relation with GH, feeding behavior, and sleep-wake patterns in rats. Endocrinology. 2002;143(4):1353-1361. [PubMed]
  6. 6.
    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. [PubMed]
  7. 7.
    Broussard J, Kilkus J, Delebecque F, et al. Elevated ghrelin predicts food intake during experimental sleep restriction. Obesity (Silver Spring). 2016;24(1):132-138. [PubMed]
  8. 8.
    King J, Wasse L, Broom D, Stensel D. Influence of brisk walking on appetite, energy intake, and plasma acylated ghrelin. Med Sci Sports Exerc. 2010;42(3):485-492. [PubMed]
  9. 9.
    Broom D, Batterham R, King J, Stensel D. Influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin, and peptide YY in healthy males. Am J Physiol Regul Integr Comp Physiol. 2009;296(1):R29-35. [PubMed]
  10. 10.
    Broom D, Stensel D, Bishop N, Burns S, Miyashita M. Exercise-induced suppression of acylated ghrelin in humans. J Appl Physiol (1985). 2007;102(6):2165-2171. [PubMed]
  11. 11.
    Stokes K, Sykes D, Gilbert K, Chen J, Frystyk J. Brief, high intensity exercise alters serum ghrelin and growth hormone concentrations but not IGF-I, IGF-II or IGF-I bioactivity. Growth Horm IGF Res. 2010;20(4):289-294. [PubMed]
  12. 12.
    Yang C, Chuang C, Kuo C, Hsu C, Tsao T. Effects of an acute bout of exercise on serum soluble leptin receptor (sOB-R) levels. J Sports Sci. 2014;32(5):446-451. [PubMed]
  13. 13.
    Adams C, Greenway F, Brantley P. Lifestyle factors and ghrelin: critical review and implications for weight loss maintenance. Obes Rev. 2011;12(5):e211-8. [PubMed]
  14. 14.
    Van P, Szlufcik K, Nielens H, et al. Training in the fasted state improves glucose tolerance during fat-rich diet. J Physiol. 2010;588(Pt 21):4289-4302. [PubMed]
  15. 15.
    Gannon M, Nuttall F. Effect of a high-protein diet on ghrelin, growth hormone, and insulin-like growth factor-I and binding proteins 1 and 3 in subjects with type 2 diabetes mellitus. Metabolism. 2011;60(9):1300-1311. [PubMed]
  16. 16.
    Lejeune M, Westerterp K, Adam T, Luscombe-Marsh N, Westerterp-Plantenga M. Ghrelin and glucagon-like peptide 1 concentrations, 24-h satiety, and energy and substrate metabolism during a high-protein diet and measured in a respiration chamber. Am J Clin Nutr. 2006;83(1):89-94. [PubMed]
  17. 17.
    Ma X, Lin L, Yue J, et al. Ghrelin receptor regulates HFCS-induced adipose inflammation and insulin resistance. Nutr Diabetes. 2013;3:e99. [PubMed]
  18. 18.
    Teff K, Elliott S, Tschöp M, et al. Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women. J Clin Endocrinol Metab. 2004;89(6):2963-2972. [PubMed]
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About the Author

I am a family physician who has served in the US Army. In 2016, I found myself overweight, out of shape, and unhealthy, so I made a change to improve my health. This blog is the chronology of my path to better health and what I have learned along the way.

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