Medical Uses of Fasting

Medical Uses of Fasting

by Chris Irvin / The Ketologist - M.S. Exercise & Nutrition Science

Over the last few years, fasting has become one of the most popular mainstream diet strategies.  From biohackers looking to improve their brain function to dieters looking for a great fat loss story, it seems like so many people have adopted a fasting lifestyle.

While mainstream use of the diet has become more popular, we often forget that fasting has strong therapeutic potential and can help manage several different medical conditions.  This isn’t anything new considering that the ancient father of medicine, Hippocrates, referred to fasting as “the greatest remedy, the physician within.” 

In this article, we are going to discuss the different medical uses of fasting and how this diet strategy can offer a lot more than just weight loss.

Fasting for Epilepsy

One of the first documented medical uses of fasting was for epilepsy. We first see fasting appear as a treatment to epilepsy in the bible.  Hippocrates and many ancient doctors prescribed fasting for epilepsy as well and until the early 1900s, fasting was still considered the primary treatment option for children with epilepsy.

Interestingly enough, fasting for epilepsy actually led to the discovery of the ketogenic diet in the 1920s due to the diet’s ability to mimic fasting while still allowing for food consumption (1).  Shortly after, anti-seizure medications came to the market and both were forgotten about until recent years.

Fasting for Medical Weight Loss

It’s hard to talk about fasting without mentioning its weight loss potential.  Fasting is an incredible strategy for not just weight loss, but specifically fat loss. Which is why if you are prescribed medical weight loss, you may benefit from incorporating fasting into your diet plan.

Fasting can contribute to weight loss through several mechanisms.  The first is that fasting reduces blood sugar and insulin which allow fat burning to take place. When we practice fasting we not only induce a state of fat burning in the short term but also in the long term as we continue to make improvements to our fasting blood sugar and our metabolic health. 

Fasting can also help with weight loss by inducing a calorie deficit.  While calories are not the end all be all for weight loss, they do still play a role.  With fasting, we can prevent ourselves from overeating and more easily create a calorie deficit to help us reach our weight loss goals.

Fasting for Diabetes

The impact fasting has on blood sugar and insulin levels is a benefit that you will see come up often when talking about the application of fasting. These benefits play a role in weight loss and even more so in diabetes and prediabetes.

Diabetes and prediabetes are conditions characterized by elevated fasting blood sugar and insulin resistance.  When we fast, we give our body a chance to metabolize blood sugar and lower our fasting levels.  The more frequently we do this the more we are able to reverse insulin resistance, the primary driver of the disease. 

Research has found that fasting incorporated long term can lead to improvements in fasting blood sugar and HbA1c, the most commonly used marker of diabetes.  

Note: Those taking diabetic medication should consult with their physician before incorporating fasting so that medication can be adjusted accordingly. 

Fasting for Cancer

I know what you’re thinking,“there’s no way fasting can be used by itself to treat cancer.” You’re right. However, research has shown its ability to support the standard of care for cancer.

Research looking at both radiation and chemotherapy have found that these treatments produce more robust results when the patient fasts prior to treatment (2,3).  Why?  Again, fasting leads to that low blood sugar we keep mentioning which is particularly beneficial for cancer since cancer cells thrive on sugar.  When patients fast before radiation or chemo they are starving cancer cells of their primary fuel source, making them weaker and more susceptible to the effects of the treatment.

In addition to being used before the standard of care, the ability of fasting to starve cancer cells and produce ketones makes it a great strategy to use between treatments to help keep cancer from spreading or coming back (4).  

Note: It is important that cancer patients eat enough food so if fasting is going to be used as a strategy, there should be a plan in place to ensure sufficient calorie intake.  Consult with a oncology nutritionist prior if you plan to fast during your cancer treatment.

Fasting for Alzheimer’s

Fasting has a profound impact on the brain, mostly due to the ketones that are produced when we fast.  Ketones are little energy molecules that the brain has a preference for due to their ability to provide more energy to the brain and activate anti-inflammatory pathways while producing less oxidative stress.  A recipe for long-term brain health.

The aging brain is characterized by an increase in insulin resistance and a subsequent decrease in energy available to the brain.  Research has found that under these conditions, ketones can still be used by the brain to help resolve this energy crisis and potentially reduce symptoms of neurodegenerative diseases (5).

Fasting for TBI

Until recent years, there was very little consideration paid to the role of nutrition in traumatic brain injury (TBI) recovery.  However, as we have begun to understand more about head trauma, we have discovered that a defining characteristic of the condition is neuroinflammation and a subsequent energy crisis.

While the research is still in its infancy, there is evidence that ketones can help alleviate the energy crisis displayed post head trauma while also working to lower the inflammation that worsens the outcome (6).

Fasting’s ability to induce ketosis could also make it a great complementary tool to use in the treatment and long-term recovery of concussions and traumatic brain injury. 

It’s important to call out the lack of randomized controlled trials available for the medical uses of fasting.  Research costs money and money typically comes from sources that have a return in mind.  Unfortunately, there isn’t much money to be made in not eating anything. 

Regardless, the mechanisms are present and the anecdotal evidence is mounting.  In time, we may find that one of the best treatments or supporting treatments to so many conditions is to not do anything at all…



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