Nathaniel Stephenson, Class of 2021
The idea of fasting to many is seen as counterproductive, nonsensical, and at times borderline insane. Tell a family member or friend that you are fasting for 24 hours or more and one will immediately see concern and worry enter the conversation. Questions such as “Aren't you starving? Do I need to take you to the hospital? You’re lying, aren’t you?” often follow.
However, many forget that a large proportion of the world population have been fasting for thousands of years. A recent Pew Research Center survey showed out of 38,000 Muslims across the world, 93% say they fast between eleven and sixteen hours every day, during Ramadan. It is thought that hunter gatherers would often go days with having little to no food because it is not as easily accessible as it is today. However, they were still able to have healthy long lasting lives without “starving themselves to death”. The goal of this article is to debunk basic myths and concerns of fasting and to propose some potential benefits for both healthy and unhealthy individuals. The definition of fasting that we will use throughout this article is the willing abstinence from all food and drink for a period of time, exceeding 24 hours, excluding drinks such as coffee, tea, and water. However, when consuming any of the previously mentioned beverages, sugar and milk is not allowed to be added. The main goal behind fasting is to reduce your caloric intake to 0 for a given period of time.
Before we discuss all the wonderful benefits that fasting can offer first we should understand what happens to our body when we are fasting. Typically the human body converts food into energy, typically in the form of glucose, and any energy that is not used is then stored up as fat. When you are fasting, Ghrelin (a hormone associated with hunger that increases food intake and promotes fat storage) will build up telling you to eat. Though because you are not eating your body needs to find energy from somewhere else. Your body starts to break down fat cells and use them for energy instead. This a very basic understanding of what happens when you fast, but it is important to understand this to appreciate the benefits.
The biggest concern for individuals considering fasting is hunger, however a study from the Medical University of Vienna took individuals who normally ate three meals a day and subjected the participants to a 33 hour fast with ghrelin being measured every twenty minutes. The results showed that there was an increase in ghrelin (hunger) at the timepoints where participants typically ate before the fast, but dropped down to normal levels after a few hours (Natalucci 2005). From a real world perspective this makes sense to many. If you ever had to skip lunch or breakfast you may have been hungry around the time you typically eat, but after an hour or two, you completely forgot how hungry you were before.
Another big finding of the study was that over the 33 hours of fasting, eating nothing made participants less hungry as the study went on. This was confirmed when over the 33 hour fast, the authors saw that ghrelin levels decreased overall during the study period.
However, this is merely a 33 hour fast. When looking at another study that examined 33 participants (including male, females, obese, and lean individauls) ghrelin levels over 84 hours of fasting, the authors concluded that over 3 days of fasting, ghrelin gradually decreased. This means participants were significantly less hungry despite not consuming any food for 3 whole days. It is important to mention that 3 days is much shorter than what would require a healthy person to starve to death. According to a British Medical Journal review on fasting, the researchers found that humans can survive without any food for 30-40 days provided that they are adequately hydrated.
Now that we have discussed that fasting is not starvation we can examine what are some potential benefits of fasting. First we can examine its effects on individuals with chronic conditions. Almost 1 in 10 Americans have type 2 diabetes, a chronic condition that affects the way your body metabolizes glucose (sugar), and is strongly associated with obesity. This is typically caused by your body being resisted to the effects of insulin, a hormone that regulates the movement of sugar into your cells. There is currently no cure for type 2 diabetes, but the current treatment of losing weight, eating well, and exercising. In a recent 2018 study patients who were currently taking diabetic medications such as insulin, followed a scheduled 24-hour fasts three times per week over a period of seven months. Over this time they were evaluated for blood sugar levels. Within 18 days all patients eliminated the need for insulin, except one (one patient discontinued 3 out of 4 medications after his fasting regimen). All patients also lowered their BMI (a measure of body fat in adults, lower is typically better if trying to lose weight) and waist circumference (Furmli 2018). The benefits of better glycemic control, lowering insulin levels, and controlling weight are not only applicable to patients that are obesse or suffer from type 2 diabetes.
Though besides what effect it can have on the diabetic population we can see the benefits of fasting on healthy individuals. However, the effects of fasting on healthy individuals are still being studied. In one study with 16 non obese male and females, subjects fasted every other day for 22 days (Heilbronn 2005). The results showed that subjects lost on average 2.5% of their initial body weight and the authors saw an average daily increase in fat oxidation (burning fat). However, hunger on fasting days did not decrease; perhaps this was caused by only having a 24 hour fasting window compared to the other studies mentioned above showing as the fasting length increased, hunger decreased.
If we were to examine the effects of fasting on healthy mice we can see some incredible benefits. Mice are typically used as models in medical testing because their genetic, biological, and behavior characteristics closely resemble humans. In a recent 2014 study the researchers concluded that fasting between 48 and 120 hours enhanced our cells ability to resist toxins in both humans and mice (Cheng 2015). Additional testing on mice showed that fasting reduced circulating insulin-like-growth factor-1 (IGF-1), a regulator for the aging process as well as rapamycin (mTOR). Decreased amounts of these during fasting are thought to signal to the body to have cells and organelles be recycled and repurposed. A paper on clinical interventions of aging paper notes that “Reduced mTOR signaling has been demonstrated to extend lifespan in different organisms.”
In summary fasting for more than 24 hours can be a non pharmacological approach to helping individuals with type 2 diabetes and obesity. It can also help with insulin resistance, fat loss, and possibly (although more research is needed) a longer lifespan. This is only the tip of the iceberg and there are a plethora of additional benefits that are currently being studied, such as its effect on helping to prevent cancer, reduce the risk of heart disease, and better your immune system.
However there are some possible downsides and it is important for the reader to decide if the disadvantages outweigh the advantages of fasting. Early research has found that fasting can increase levels of cortisol, the body’s stress hormone. Long term increases in cortisol levels can destroy healthy cells and result in chronic illnesses. Fasting may not be beneficial for individuals who are exposed to large amounts of stress or believe they are sensitive to stress. Additionally, individuals with previous cases of eating disorders, such as anorexia or binge eating, may not see the same benefits as others.
This article is meant to shine light on the benefits of fasting for both healthy and unhealthy individuals while debunking false claims typically associated with fasting. If someone is interested in fasting it is recommended that they slowly build up their fasting periods before doing a multiple day fast. Before fasting individuals should speak with a medical professional if fasting is the right decision for them. Regardless, fasting is a powerful tool that can be used to lower your BMI, combat diabetes and obesity, reduce aging, improve overall health, possibly help against preventing cancer and improving cognitive ability.
This article is dedicated to Dr. Asghar Husain, a distinguished orthopedic surgeon, a mentor, and a friend. Hard work, integrity, eager for knowledge, and understanding are just a few of his attributes. Dr. Husain has inspired me to further my career in medicine focusing on finding the best ways to improve the lives of others and to never stop asking questions.
Works Cited
Ghani F. Most Muslims say they fast during Ramadan. Pew Research Center. 2013 Jul 9 [accessed 2019 Nov 13]. https://www.pewresearch.org/fact-tank/2013/07/09/global-median-of-93-of-muslims-say-they-fast-during-ramadan/
Natalucci G, Riedl S, Gleiss A, Zidek T, Frisch H. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. European Journal of Endocrinology. 2005;152(6):845–850. doi:10.1530/eje.1.01919
Espelund U, Hansen TK, Højlund K, Beck-Nielsen H, Clausen JT, Hansen BS, Ørskov H, Jørgensen JOL, Frystyk J. Fasting Unmasks a Strong Inverse Association between Ghrelin and Cortisol in Serum: Studies in Obese and Normal-Weight Subjects. The Journal of Clinical Endocrinology & Metabolism. 2005;90(2):741–746. doi:10.1210/jc.2004-0604
Furmli S, Elmasry R, Ramos M, Fung J. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Reports. 2018 Sep. doi:10.1136/bcr-2017-221854
Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. The American Journal of Clinical Nutrition. 2005;81(1):69–73. doi:10.1093/ajcn/81.1.69
Cheng C-W, Adams GB, Perin L, Wei M, Zhou X, Lam BS, Da Sacco S, Mirisola M, Quinn DI, Dorff TB, et al. Prolonged Fasting Reduces IGF-1/PKA to Promote Hematopoietic-Stem-Cell-Based Regeneration and Reverse Immunosuppression. Cell Stem Cell. 2016;18(2):291–292. doi:10.1016/j.stem.2016.01.018
However, many forget that a large proportion of the world population have been fasting for thousands of years. A recent Pew Research Center survey showed out of 38,000 Muslims across the world, 93% say they fast between eleven and sixteen hours every day, during Ramadan. It is thought that hunter gatherers would often go days with having little to no food because it is not as easily accessible as it is today. However, they were still able to have healthy long lasting lives without “starving themselves to death”. The goal of this article is to debunk basic myths and concerns of fasting and to propose some potential benefits for both healthy and unhealthy individuals. The definition of fasting that we will use throughout this article is the willing abstinence from all food and drink for a period of time, exceeding 24 hours, excluding drinks such as coffee, tea, and water. However, when consuming any of the previously mentioned beverages, sugar and milk is not allowed to be added. The main goal behind fasting is to reduce your caloric intake to 0 for a given period of time.
Before we discuss all the wonderful benefits that fasting can offer first we should understand what happens to our body when we are fasting. Typically the human body converts food into energy, typically in the form of glucose, and any energy that is not used is then stored up as fat. When you are fasting, Ghrelin (a hormone associated with hunger that increases food intake and promotes fat storage) will build up telling you to eat. Though because you are not eating your body needs to find energy from somewhere else. Your body starts to break down fat cells and use them for energy instead. This a very basic understanding of what happens when you fast, but it is important to understand this to appreciate the benefits.
The biggest concern for individuals considering fasting is hunger, however a study from the Medical University of Vienna took individuals who normally ate three meals a day and subjected the participants to a 33 hour fast with ghrelin being measured every twenty minutes. The results showed that there was an increase in ghrelin (hunger) at the timepoints where participants typically ate before the fast, but dropped down to normal levels after a few hours (Natalucci 2005). From a real world perspective this makes sense to many. If you ever had to skip lunch or breakfast you may have been hungry around the time you typically eat, but after an hour or two, you completely forgot how hungry you were before.
Another big finding of the study was that over the 33 hours of fasting, eating nothing made participants less hungry as the study went on. This was confirmed when over the 33 hour fast, the authors saw that ghrelin levels decreased overall during the study period.
However, this is merely a 33 hour fast. When looking at another study that examined 33 participants (including male, females, obese, and lean individauls) ghrelin levels over 84 hours of fasting, the authors concluded that over 3 days of fasting, ghrelin gradually decreased. This means participants were significantly less hungry despite not consuming any food for 3 whole days. It is important to mention that 3 days is much shorter than what would require a healthy person to starve to death. According to a British Medical Journal review on fasting, the researchers found that humans can survive without any food for 30-40 days provided that they are adequately hydrated.
Now that we have discussed that fasting is not starvation we can examine what are some potential benefits of fasting. First we can examine its effects on individuals with chronic conditions. Almost 1 in 10 Americans have type 2 diabetes, a chronic condition that affects the way your body metabolizes glucose (sugar), and is strongly associated with obesity. This is typically caused by your body being resisted to the effects of insulin, a hormone that regulates the movement of sugar into your cells. There is currently no cure for type 2 diabetes, but the current treatment of losing weight, eating well, and exercising. In a recent 2018 study patients who were currently taking diabetic medications such as insulin, followed a scheduled 24-hour fasts three times per week over a period of seven months. Over this time they were evaluated for blood sugar levels. Within 18 days all patients eliminated the need for insulin, except one (one patient discontinued 3 out of 4 medications after his fasting regimen). All patients also lowered their BMI (a measure of body fat in adults, lower is typically better if trying to lose weight) and waist circumference (Furmli 2018). The benefits of better glycemic control, lowering insulin levels, and controlling weight are not only applicable to patients that are obesse or suffer from type 2 diabetes.
Though besides what effect it can have on the diabetic population we can see the benefits of fasting on healthy individuals. However, the effects of fasting on healthy individuals are still being studied. In one study with 16 non obese male and females, subjects fasted every other day for 22 days (Heilbronn 2005). The results showed that subjects lost on average 2.5% of their initial body weight and the authors saw an average daily increase in fat oxidation (burning fat). However, hunger on fasting days did not decrease; perhaps this was caused by only having a 24 hour fasting window compared to the other studies mentioned above showing as the fasting length increased, hunger decreased.
If we were to examine the effects of fasting on healthy mice we can see some incredible benefits. Mice are typically used as models in medical testing because their genetic, biological, and behavior characteristics closely resemble humans. In a recent 2014 study the researchers concluded that fasting between 48 and 120 hours enhanced our cells ability to resist toxins in both humans and mice (Cheng 2015). Additional testing on mice showed that fasting reduced circulating insulin-like-growth factor-1 (IGF-1), a regulator for the aging process as well as rapamycin (mTOR). Decreased amounts of these during fasting are thought to signal to the body to have cells and organelles be recycled and repurposed. A paper on clinical interventions of aging paper notes that “Reduced mTOR signaling has been demonstrated to extend lifespan in different organisms.”
In summary fasting for more than 24 hours can be a non pharmacological approach to helping individuals with type 2 diabetes and obesity. It can also help with insulin resistance, fat loss, and possibly (although more research is needed) a longer lifespan. This is only the tip of the iceberg and there are a plethora of additional benefits that are currently being studied, such as its effect on helping to prevent cancer, reduce the risk of heart disease, and better your immune system.
However there are some possible downsides and it is important for the reader to decide if the disadvantages outweigh the advantages of fasting. Early research has found that fasting can increase levels of cortisol, the body’s stress hormone. Long term increases in cortisol levels can destroy healthy cells and result in chronic illnesses. Fasting may not be beneficial for individuals who are exposed to large amounts of stress or believe they are sensitive to stress. Additionally, individuals with previous cases of eating disorders, such as anorexia or binge eating, may not see the same benefits as others.
This article is meant to shine light on the benefits of fasting for both healthy and unhealthy individuals while debunking false claims typically associated with fasting. If someone is interested in fasting it is recommended that they slowly build up their fasting periods before doing a multiple day fast. Before fasting individuals should speak with a medical professional if fasting is the right decision for them. Regardless, fasting is a powerful tool that can be used to lower your BMI, combat diabetes and obesity, reduce aging, improve overall health, possibly help against preventing cancer and improving cognitive ability.
This article is dedicated to Dr. Asghar Husain, a distinguished orthopedic surgeon, a mentor, and a friend. Hard work, integrity, eager for knowledge, and understanding are just a few of his attributes. Dr. Husain has inspired me to further my career in medicine focusing on finding the best ways to improve the lives of others and to never stop asking questions.
Works Cited
Ghani F. Most Muslims say they fast during Ramadan. Pew Research Center. 2013 Jul 9 [accessed 2019 Nov 13]. https://www.pewresearch.org/fact-tank/2013/07/09/global-median-of-93-of-muslims-say-they-fast-during-ramadan/
Natalucci G, Riedl S, Gleiss A, Zidek T, Frisch H. Spontaneous 24-h ghrelin secretion pattern in fasting subjects: maintenance of a meal-related pattern. European Journal of Endocrinology. 2005;152(6):845–850. doi:10.1530/eje.1.01919
Espelund U, Hansen TK, Højlund K, Beck-Nielsen H, Clausen JT, Hansen BS, Ørskov H, Jørgensen JOL, Frystyk J. Fasting Unmasks a Strong Inverse Association between Ghrelin and Cortisol in Serum: Studies in Obese and Normal-Weight Subjects. The Journal of Clinical Endocrinology & Metabolism. 2005;90(2):741–746. doi:10.1210/jc.2004-0604
Furmli S, Elmasry R, Ramos M, Fung J. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Reports. 2018 Sep. doi:10.1136/bcr-2017-221854
Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. The American Journal of Clinical Nutrition. 2005;81(1):69–73. doi:10.1093/ajcn/81.1.69
Cheng C-W, Adams GB, Perin L, Wei M, Zhou X, Lam BS, Da Sacco S, Mirisola M, Quinn DI, Dorff TB, et al. Prolonged Fasting Reduces IGF-1/PKA to Promote Hematopoietic-Stem-Cell-Based Regeneration and Reverse Immunosuppression. Cell Stem Cell. 2016;18(2):291–292. doi:10.1016/j.stem.2016.01.018
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