I keep hearing over an over how humans can satisfy their entire daily caloric need in one sitting at a fast food restaurant. At the same time I'm looking at the kitchen plates, cups, etc, and they also seem to be getting bigger.

This makes me ask the question - was breakfast-lunch-dinner a concept invented because people:

  • Could not make enough food?
  • Could not make food fast enough?
  • Could not make food with high enough caloric intake?

I'm thinking along the lines of: you can make only so much tasteless porridge and stuff it in your mouth before it gets cold. At the same time I know that gorillas and some other primates have a very long (8 hours?) feeding session of eating raw vegetation throughout the day.

Is there a biological explanation why human food intake should be spread into X distinct sittings?

  • 2
    $\begingroup$ A biological reason? I don't think so. I think this is more a cultural thing. It is before, during and after work. $\endgroup$
    – Chris
    Apr 13, 2014 at 10:17
  • $\begingroup$ In stone age I dont think it would be beneficial to have a fixed schedule. $\endgroup$
    – biogirl
    Apr 13, 2014 at 13:30

2 Answers 2


The three meals a day seems to be a cultural trait. Then what is the optimal number of meals a day? It is not known. Here are the results of some studies:

Reduced meal frequency:

It was found that the body can adapt to a single meal a day by modifying circulating hormone levels and glucose tolerance [1]. However it does not modify lipogenesis rates [2]. It may support cardiovascular disease risk factors [8].

Increased meal frequency:

Although there are studies that claim 5-6 meals a day help in maintenance of weight loss [3], others claim this habit increases hunger and the desire to eat and has no significant effect on fat oxidation [4]. A higher number of daily meals is recommended to the elderly suffering from cardiovascular diseases [5] because less but square meals lead to a redistribution of blood to the gastro-intestinal tract to increase absorption, which causes reduction of blood pressure [6].


Energy balance is more important than meal frequency. As this study says [7]:

... there is no evidence that weight loss on hypoenergetic regimens is altered by meal frequency. We conclude that any effects of meal pattern on the regulation of body weight are likely to be mediated through effects on the food intake side of the energy balance equation.


  1. Carlson O, Martin B, Stote KS, Golden E, Maudsley S, Najjar SS, Ferrucci L, Ingram DK, Longo DL, Rumpler WV, Baer DJ, Egan J, Mattson MP. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metab. Clin. Exp. 2007 Dec;56(12):1729-34. doi: 10.1016/j.metabol.2007.07.018. PubMed PMID: 17998028.
  2. Jones PJ, Namchuk GL, Pederson RA. Meal frequency influences circulating hormone levels but not lipogenesis rates in humans. Metab. Clin. Exp. 1995 Feb;44(2):218-23. PubMed PMID: 7869919.
  3. Bachman JL, Phelan S, Wing RR, Raynor HA. Eating frequency is higher in weight loss maintainers and normal-weight individuals than in overweight individuals. J Am Diet Assoc. 2011 Nov;111(11):1730-4. doi: 10.1016/j.jada.2011.08.006. PubMed PMID: 22027056.
  4. Ohkawara K, Cornier MA, Kohrt WM, Melanson EL. Effects of increased meal frequency on fat oxidation and perceived hunger. Obesity (Silver Spring). 2013 Feb;21(2):336-43. doi: 10.1002/oby.20032. PubMed PMID: 23404961.
  5. Ortega RM, Redondo MR, Zamora MJ, López-Sobaler AM, Quintas ME, Andrés P, Gaspar MJ, Requejo AM. [Relationship between the number of daily meals and the energy and nutrient intake in the elderly. Effect on various cardiovascular risk factors]. Nutr Hosp. 1998;13(4):186-92. PubMed PMID: 9780751.
  6. Westenend M, Lenders JW, Thien T. The course of blood pressure after a meal: a difference between young and elderly subjects. J Hypertens Suppl. 1985 Dec;3(3):S417-9. PubMed PMID: 2856754.
  7. Bellisle F, McDevitt R, Prentice AM. Meal frequency and energy balance. Br. J. Nutr. 1997 Apr;77 Suppl 1:S57-70. PubMed PMID: 9155494.
  8. Stote KS, Baer DJ, Spears K, Paul DR, Harris GK, Rumpler WV, Strycula P, Najjar SS, Ferrucci L, Ingram DK, Longo DL, Mattson MP. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am. J. Clin. Nutr. 2007 Apr;85(4):981-8. PubMed PMID: 17413096.

The answers to your 3 questions are no, no and no. The 3 meal concept is more of a recent concept when you compare that Ancient Romans used to frown upon eating more than once a day. You can read a brief history of how food habits evolved in this article. Food habits have been variable all throughout history and it still varies by culture. Food habits divided by different eras can be read in this article. In the current age and time, I think we just try to spread our calorie intake over the day and that is why we try to stick to the 3 meal concept.(reference). There is no biological reason as far as I could see (reference). Just a matter of improved health consciousness and understanding of the human body. This article contain some interesting thoughts on meal timings and optimal intake.

  • $\begingroup$ could you perhaps share/summarize an important quote from some of these sources? I ask because if any of your links go dead (which is surprisingly common) your answer loses much of its value. Just want to make sure posts remain helpful for as long as possible :). Thanks! $\endgroup$ Feb 12, 2018 at 4:32

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