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Hunger: why it comes and how to ride it out

Hunger comes in waves that rise and fall on their own. Here's the science, and what actually helps

Beginner5 min8 sources

Hunger is the main reason people give up on fasting, so it's worth understanding. The surprising part is that hunger isn't a simple fuel gauge that empties steadily until you eat. It rises and falls in waves, mostly on a schedule your body has learned, and each wave passes on its own.

Meet ghrelin, your meal-time alarm

Your stomach releases a hormone called ghrelin that tells your brain it's time to eat. Researchers who measured it 38 times over a day found that it almost doubled just before each meal and fell to its lowest within an hour of eating 1. A later study took away clocks and food cues and let people ask for dinner whenever they wanted: in all but one of them, ghrelin still rose before the meal, closely tracking how hungry they felt 8.

Hunger passes, even if you don't eat

Here's the part that changes how fasting feels. When healthy volunteers fasted for 24 hours with blood samples every 20 minutes, their ghrelin still rose at the times they normally ate, and then fell again on its own, without any food. Across the whole day, their ghrelin levels actually drifted down 2.

Your hunger rhythm can change

Because ghrelin follows a learned schedule, it can learn a new one. When adults with overweight ate all their food within an early 6-hour window for four days, their average ghrelin fell and their hunger became more even across the day 3.

What actually helps

Some things make hunger louder, and some make it quieter. Three have good evidence behind them.

Sources

  1. Cummings DE, Purnell JQ, Frayo RS, et al. A preprandial rise in plasma ghrelin levels suggests a role in meal initiation in humans. Diabetes. 2001;50(8):1714-9. doi.org/10.2337/diabetes.50.8.1714
  2. Natalucci G, Riedl S, Gleiss A, et al. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. Eur J Endocrinol. 2005;152(6):845-50. doi.org/10.1530/eje.1.01919
  3. Ravussin E, Beyl RA, Poggiogalle E, et al. Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity (Silver Spring). 2019;27(8):1244-1254. doi.org/10.1002/oby.22518
  4. Hoddy KK, Gibbons C, Kroeger CM, et al. Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting. Clin Nutr. 2016;35(6):1380-1385. doi.org/10.1016/j.clnu.2016.03.011
  5. Spiegel K, Tasali E, Penev P, et al. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004;141(11):846-50. doi.org/10.7326/0003-4819-141-11-200412070-00008
  6. Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S-1329S. doi.org/10.3945/ajcn.114.084038
  7. Dennis EA, Dengo AL, Comber DL, et al. Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring). 2010;18(2):300-7. doi.org/10.1038/oby.2009.235
  8. Cummings DE, Frayo RS, Marmonier C, et al. Plasma ghrelin levels and hunger scores in humans initiating meals voluntarily without time- and food-related cues. Am J Physiol Endocrinol Metab. 2004;287(2):E297-304. doi.org/10.1152/ajpendo.00582.2003

A note on health

Fasting Tracker is designed for general wellness and is not a medical device. Fasting is not right for everyone. If you are pregnant, diabetic, have a history of eating disorders or take medication, talk to your doctor first, and before any extended fast.