Where did the idea of therapeutic fasting come from?
The Benefits of Fasting for Healing
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
The story of life on earth is a story of starvation. Ash from massive volcanoes and asteroids block out the sun, killing the plants, which then killed most everything else. As Darwin pointed out though, from this “war of nature, from famine and death, the most exalted object that we are capable of conceiving” arose—namely us.
We are “particularly well-adapted to prolonged fasting.” Evolving in a context of scarcity is believed to have shaped “our exceptional ability to store large amounts of [calories] when food is available.” Of course, now our ability to easily pack on pounds is leading to modern diseases like obesity and type 2 diabetes, but without the ability to store so much body fat, we may not have made it to tell the tale.
And it’s not just asteroids millions of years ago. “All of Upper Egypt was dying of hunger,” reads an inscription on an Egyptian tomb from about 4,000 years ago, “to such a degree that everyone had come to eating his children…” Or, just hundreds of years ago: “Parents killed their children and children killed parents” and ate them, and “the bodies of executed criminals were eagerly snatched from the gallows.” Wiping out as many as two-thirds of the population of Italy and one-third of the population of Paris. So, we don’t have to go back to ancient history. Even the most secure and affluent populations of today need only trace their history back a short distance. For example, there have been nearly 200 famines in Britain over the last 2,000 years.
Now, we tend to be suffering from too much food, which carries its own problems, but might there be any negative consequences to not ever starving? This was a question raised 50 years ago. I mean, if our physiology is so well-tuned to periodic starvation, maybe by eliminating that we may be doing harm to our overall well-being? We just didn’t know.
The lack of research in the area of starvation was attributed to the “difficulty of securing willing human subjects.’’ So, what little we had came from unwilling subjects. Physicians within the Warsaw Ghetto made detailed accounts before they themselves succumbed; or Irish Republican prisoners starving themselves to death after up to 73 days on hunger strike. But starvation isn’t necessarily the same as fasting, an issue raised in medical journals over a century ago. “Starvation is normally a forced, mentally stressful, and chronic condition, whereas [therapeutic] fasting is voluntary, limited in duration, and usually practiced by people [who start out with adequate nutrition].”
Therapeutic fasting? Where did we get this idea of fasting therapy, fasting for medical purposes? It may have originally arose out of the observation that when people get acutely ill they tend to lose their appetite; so, maybe there’s something in the body’s wisdom to stopping eating. That’s presumably where the whole “starve a fever” folklore came from.
There was this sense that fasting affords physiological rest for the body, not just for the digestive tract, but throughout, allowing the body to concentrate on healing. It was evidently an open secret that veterinarians used to hospitalize dogs only to fast them back to health; and so maybe, the theory went, it might work for people too.
Beyond just freeing up all the resources that would normally be used for nutrient digestion and storage, there’s this concept that during fasting, our cells switch over to some sort of protection mode. Why would fasting reduce free radical damage and inflammation and bolster cellular protection? It’s the that-which-doesn’t-kill-us-makes-us-stronger concept known as hormesis. So, that’s kind of the opposite of the let-the-body-rest theory. It’s more like let-the-body-stress. The stress of fasting may steel the body against other stresses coming your way. This was demonstrated perhaps most starkly in a set of cringeworthy experiments in which mice were blasted with Hiroshima-level gamma radiation sufficient to kill 50 percent within two weeks. But, of the mice who had first been intermittently fasted for six weeks before, not a single one died.
It’s this kind of dramatic data that led to extraordinary claims, like therapeutic fasting could drive half of all doctors out of business. But you don’t know, until you put it to the test, which we’ll explore next.
Please consider volunteering to help out on the site.
- McCue MD. An Introduction to Fasting, Starvation, and Food Limitation. In: McCue MD, ed. Comparative Physiology of Fasting, Starvation, and Food Limitation. Berlin, Heidelberg: Springer Berlin Heidelberg; 2012:1-5.
- Darwin CR. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. [1st edition]. Published 1859.
- Prentice AM. Starvation in humans: Evolutionary background and contemporary implications. Mech Ageing Dev. 2005;126(9 SPEC. ISS.):976-981.
- Elia M. Hunger Disease. Clin Nutr. 2000;19(6):379-386.
- Runcie J. Energy Provision, Tissue Utilization, and Weight Loss in Prolonged Starvation. Br Med J. 1974;2(5915):352-356.
- Benedict FG. The influence of inanition on metabolism. Washington: Carnegie Institution of Washington. 1907.
- Johnstone AM. Fasting - The ultimate diet? Obes Rev. 2007;8(3):211-222.
- Connell AM, Smith CL, Somsel M. Absence of effect of bran on blood-lipids. Lancet. 1975;1(7905):496-497. | https://doi.org/10.1016/s0140-6736(75)92836-6
- Wilhelmi De Toledo F, Buchinger A, Burggrabe H, et al. Fasting therapy - An expert panel update of the 2002 consensus guidelines. Forsch Komplementarmed. 2013;20(6):434-443.
- Michalsen A, Li C. Fasting therapy for treating and preventing disease - Current state of evidence. Forsch Komplementarmed. 2013;20(6):444-453.
- Murray MJ, Murray AB. Anorexia of infection as a mechanism of host defense. Am J Clin Nutr. 1979;32(3):593-596.
- Benedict AL. Fasting. Medical Review of Reviews. 1918;24:80-7.
- Longo VD, Mattson MP. Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism. 2014;19(2):181-192.
- Kozubik A, Kozubík A, Pospísil M. Protective effect of intermittent fasting on the mortality of gamma-irradiated mice. Strahlentherapie. 1982;158(12):734-738.
- Michalsen A, Hoffmann B, Moebus S, Bäcker M, Langhorst J, Dobos GJ. Incorporation of fasting therapy in an integrative medicine ward: evaluation of outcome, safety, and effects on lifestyle adherence in a large prospective cohort study. J Altern Complement Med. 2005;11(4):601-7.
- Cahill GF, Owen OE. Starvation and survival. Trans Am Clin Climatol Assoc. 1968;79:13-20. https://www.ncbi.nlm.nih.gov/pubmed/5667163
- Page CE. Should therapeutic fasting be termed starving?--its employment in typhoid fever and other diseases. Med Rec. 1894;45(8):230.
Video production by Glass Entertainment
Motion graphics by Avocado Video
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
The story of life on earth is a story of starvation. Ash from massive volcanoes and asteroids block out the sun, killing the plants, which then killed most everything else. As Darwin pointed out though, from this “war of nature, from famine and death, the most exalted object that we are capable of conceiving” arose—namely us.
We are “particularly well-adapted to prolonged fasting.” Evolving in a context of scarcity is believed to have shaped “our exceptional ability to store large amounts of [calories] when food is available.” Of course, now our ability to easily pack on pounds is leading to modern diseases like obesity and type 2 diabetes, but without the ability to store so much body fat, we may not have made it to tell the tale.
And it’s not just asteroids millions of years ago. “All of Upper Egypt was dying of hunger,” reads an inscription on an Egyptian tomb from about 4,000 years ago, “to such a degree that everyone had come to eating his children…” Or, just hundreds of years ago: “Parents killed their children and children killed parents” and ate them, and “the bodies of executed criminals were eagerly snatched from the gallows.” Wiping out as many as two-thirds of the population of Italy and one-third of the population of Paris. So, we don’t have to go back to ancient history. Even the most secure and affluent populations of today need only trace their history back a short distance. For example, there have been nearly 200 famines in Britain over the last 2,000 years.
Now, we tend to be suffering from too much food, which carries its own problems, but might there be any negative consequences to not ever starving? This was a question raised 50 years ago. I mean, if our physiology is so well-tuned to periodic starvation, maybe by eliminating that we may be doing harm to our overall well-being? We just didn’t know.
The lack of research in the area of starvation was attributed to the “difficulty of securing willing human subjects.’’ So, what little we had came from unwilling subjects. Physicians within the Warsaw Ghetto made detailed accounts before they themselves succumbed; or Irish Republican prisoners starving themselves to death after up to 73 days on hunger strike. But starvation isn’t necessarily the same as fasting, an issue raised in medical journals over a century ago. “Starvation is normally a forced, mentally stressful, and chronic condition, whereas [therapeutic] fasting is voluntary, limited in duration, and usually practiced by people [who start out with adequate nutrition].”
Therapeutic fasting? Where did we get this idea of fasting therapy, fasting for medical purposes? It may have originally arose out of the observation that when people get acutely ill they tend to lose their appetite; so, maybe there’s something in the body’s wisdom to stopping eating. That’s presumably where the whole “starve a fever” folklore came from.
There was this sense that fasting affords physiological rest for the body, not just for the digestive tract, but throughout, allowing the body to concentrate on healing. It was evidently an open secret that veterinarians used to hospitalize dogs only to fast them back to health; and so maybe, the theory went, it might work for people too.
Beyond just freeing up all the resources that would normally be used for nutrient digestion and storage, there’s this concept that during fasting, our cells switch over to some sort of protection mode. Why would fasting reduce free radical damage and inflammation and bolster cellular protection? It’s the that-which-doesn’t-kill-us-makes-us-stronger concept known as hormesis. So, that’s kind of the opposite of the let-the-body-rest theory. It’s more like let-the-body-stress. The stress of fasting may steel the body against other stresses coming your way. This was demonstrated perhaps most starkly in a set of cringeworthy experiments in which mice were blasted with Hiroshima-level gamma radiation sufficient to kill 50 percent within two weeks. But, of the mice who had first been intermittently fasted for six weeks before, not a single one died.
It’s this kind of dramatic data that led to extraordinary claims, like therapeutic fasting could drive half of all doctors out of business. But you don’t know, until you put it to the test, which we’ll explore next.
Please consider volunteering to help out on the site.
- McCue MD. An Introduction to Fasting, Starvation, and Food Limitation. In: McCue MD, ed. Comparative Physiology of Fasting, Starvation, and Food Limitation. Berlin, Heidelberg: Springer Berlin Heidelberg; 2012:1-5.
- Darwin CR. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. [1st edition]. Published 1859.
- Prentice AM. Starvation in humans: Evolutionary background and contemporary implications. Mech Ageing Dev. 2005;126(9 SPEC. ISS.):976-981.
- Elia M. Hunger Disease. Clin Nutr. 2000;19(6):379-386.
- Runcie J. Energy Provision, Tissue Utilization, and Weight Loss in Prolonged Starvation. Br Med J. 1974;2(5915):352-356.
- Benedict FG. The influence of inanition on metabolism. Washington: Carnegie Institution of Washington. 1907.
- Johnstone AM. Fasting - The ultimate diet? Obes Rev. 2007;8(3):211-222.
- Connell AM, Smith CL, Somsel M. Absence of effect of bran on blood-lipids. Lancet. 1975;1(7905):496-497. | https://doi.org/10.1016/s0140-6736(75)92836-6
- Wilhelmi De Toledo F, Buchinger A, Burggrabe H, et al. Fasting therapy - An expert panel update of the 2002 consensus guidelines. Forsch Komplementarmed. 2013;20(6):434-443.
- Michalsen A, Li C. Fasting therapy for treating and preventing disease - Current state of evidence. Forsch Komplementarmed. 2013;20(6):444-453.
- Murray MJ, Murray AB. Anorexia of infection as a mechanism of host defense. Am J Clin Nutr. 1979;32(3):593-596.
- Benedict AL. Fasting. Medical Review of Reviews. 1918;24:80-7.
- Longo VD, Mattson MP. Fasting: Molecular Mechanisms and Clinical Applications. Cell Metabolism. 2014;19(2):181-192.
- Kozubik A, Kozubík A, Pospísil M. Protective effect of intermittent fasting on the mortality of gamma-irradiated mice. Strahlentherapie. 1982;158(12):734-738.
- Michalsen A, Hoffmann B, Moebus S, Bäcker M, Langhorst J, Dobos GJ. Incorporation of fasting therapy in an integrative medicine ward: evaluation of outcome, safety, and effects on lifestyle adherence in a large prospective cohort study. J Altern Complement Med. 2005;11(4):601-7.
- Cahill GF, Owen OE. Starvation and survival. Trans Am Clin Climatol Assoc. 1968;79:13-20. https://www.ncbi.nlm.nih.gov/pubmed/5667163
- Page CE. Should therapeutic fasting be termed starving?--its employment in typhoid fever and other diseases. Med Rec. 1894;45(8):230.
Video production by Glass Entertainment
Motion graphics by Avocado Video
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The Benefits of Fasting for Healing
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Content URLDoctor's Note
Initially I had put off doing studies on fasting, since there were so few good studies, but there’s been an explosion in research interest in the last few years. Stay tuned for The World’s Largest Fasting Study.
I do have a bunch of studies already up on fasting and weight loss, though, due to my work on How Not to Diet:
- Benefits of Fasting for Weight Loss Put to the Test
- Is Fasting Beneficial for Weight Loss?
- Is Fasting for Weight Loss Safe?
- Alternate-Day Intermittent Fasting Put to the Test
- Is Alternate-Day Intermittent Fasting Safe?
- The 5-2 Diet and the Fasting-Mimicking Diet Put to the Test
- Time-Restricted Eating Put to the Test
- The Benefits of Early Time-Restricted Eating
For all of my videos on fasting, see the topic page.
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