Intermittent Fasting in the Treatment of Breast Cancer

Why are Traditional Oncologists Suddenly More interested in Intermittent Fasting in the Treatment of Breast Cancer?

by Edison de Mello, MD, PhD

Research has shown that breast cancer is one of at least 13 cancers sensitive to obesity and fat composition. Since fatty tissue promotes breast cancer's development and growth, weight-loss strategies, such as intermittent fasting or IF, can help lower fat and promote a healthy balance between fat and muscle.

Also, there is an impressive body of research demonstrating the role of insulin and glucose in the growth of breast cancer. Given that hormones like estrogen fuel the growth of cancer cells in nearly 80% of breast cancer cases, the interplay of insulin with estrogen and excess body fat can accelerate insulin production, leading to an increase in cancer cells. 

So, what is the role of Intermittent Fasting in treating breast Cancer?

To reduce fat and improve insulin levels, which can help lower estrogen levels and slow the growth of breast tumors.


Hyperglycemia and chemotherapy

 Studies on Fasting and cancer cells indicate that high glucose levels in combination with chemotherapy is associated with an increased risk of infections and a significant increase in overall mortality. 


The theory is that lower blood sugar levels help protect healthy heart cells from the side effects of powerful chemotherapeutic agents. This protective factor is due to a genetic signalling pathway called PKA/EGR1 in mammalian cells that regulate cellular protection and aging.



Similarly, too many "new ideas" in the modern-day, Intermittent Fasting is not new. In fact, humans have intermittently fasted throughout our evolution. Whether it was because the food was not available or as part of a religious practice such as Islam, Christianity, and Buddhism, intermittent Fasting is as old as eating itself. And to go further than the beginning of religion, since our ancestors did not have year-round available food or the means to conserve it, intermittent Fasting was a means of survival. 


Many of the oldest healing systems have recommended fasting as an integral method of healing and prevention. Hippocrates, for example, believed that Fasting enabled the body to heal itself.


Humans have had long periods of famine in their history through the ages, although it is influenced by many factors. Historically, most organisms have lived in environments of fluctuating food availability, during which periods of starvation were commonly encountered, and evolution has been selected for organisms that can withstand starvation.


 "Intermittent fasting can promote diversity of gut bacteria, leading to positive brain/mood changes and better sugar Balancing." Mello


How does it work?

Intermittent Fasting (IF) today can be defined as the decision that we make to consciously skip meals to optimize health. In other words, it is when we choose to eat during a specific window of the day and skip certain meals during the rest. We do so to benefit from the many healing changes that can happen on both the cellular and molecular levels in our bodies. Intermittent Fasting prompts our bodies to change certain hormone levels to make fat more readily accessible. In contrast, the cellular repair processes and the critical gene expression become more efficient.


Let me use human growth hormone levels (HGH) as an example. Current research shows that HGH can increase by as much as 5-fold during intermittent Fasting (IF), increasing the loss of fat while promoting muscle gain. Insulin levels also drop dramatically during intermittent Fasting, making stored body fat more readily accessible. In addition, by signaling cells to digest and remove old and dysfunctional proteins built up inside cells, IF increases cellular repair processes, a necessary DNA mechanism used to repair oxidative damage. In addition to lowering insulin and increasing growth hormone levels, IF also increases the release of the fat-burning hormone norepinephrine.


For newbies looking to try intermittent Fasting, what's the best way to get one's feet wet? (I've read that if you stop eating a few hours before bed and don't eat again for 12 hours, that's an excellent place to start. True?) 


True. There are a few methods of intermittent fasting. They all involve splitting the day or week into “eating periods” and “fasting periods.” During the fasting periods, one can eat either very little or nothing at all. Below are the three most common methods: 

  • The Lean Gains Protocol: Also known as the 16/8 method, it involves skipping breakfast and restricting your daily eating period to 8 hours, for example from 1 pm to 9 pm. Then “fast” for 16 hours in between. 
  • Eat-Stop-Eat: It involves fasting for 24 hours, once or twice a week; that is, no eating from dinner to dinner. 
  • The 5:2 protocol: It involves eating only 500-600 calories on 2 non-consecutive days of the week; for example, on Tuesday and Thursday. 


Studies show that intermittent fasting can be a very powerful weight loss tool as well.

 A 2011 study published in the International Journal of Obesity involved 107 obese premenopausal women who followed an intermittent-fasting-type plan showed that after six months, those who intermittently fasted lost an average of 14 pounds each. Another study in 2014 showed that Intermittent fasting (IF) lead to a weight loss of 3-8% over periods of 3-24 weeks.

Given that less calories are being consumed, IF protocols should, in most cases, lead to weight loss. The problem arises when compensating eating happens. That is, when one eats more than usual during the eating periods. 

IF has also been shown to decrease inflammation, LDL cholesterol and triglycerides levels and protect against Alzheimer’s by increasing a brain hormone called Brain-Derived Neurotropic Factor (BDNF). In addition, animal studies have shown that it can also help prevent cancer. 


But how does it work? 

Intermittent fasting (IF) is energy efficient. During eating the body spends time, sometimes many hours depending on what it is being consumed, processing the food and burning it to be used as energy rather than stored fat. This is especially true for carbohydrates/sugars, which the body prefers to burn as energy before it uses any other source. However, during the fasting state, because the body does not have a recently consumed meal to use as energy, it pulls the energy it needs to function from the fat stored in your body, rather than the glucose in the blood or glycogen in your muscles/liver. 


Intermittent fasting can be very beneficial to our gut

That is because the gut bacteria have a circadian cycle which means that different species are more prominent at different types of day.

Research has shown that in obesity, for example, this cycle is blunted leading the bacteria to influence the food choices that we make. Studies have shown us that time- restricted feeding can restore the normal circadian cycle of gut bacteria and significantly improve metabolism.


But intermittent fasting is not for everyone. 

I do not recommend it for underweight patients, pregnant women and for those with an eating disorder, diabetes, high blood pressure or who take any medication. And although there is some evidence that intermittent fasting may not be as beneficial to women as it is for men, the jury is still out because IF is to believe to also have the potential to influence a woman’s menstrual cycle.  

How to Start

We all likely already done some form of intermittent fasting in your life. Most of us have at one time or another not eaten dinner, slept late and not eaten until 2-4 hour later, or gotten sick and did not feel like eating much. Some of us are actually “not big eaters” and naturally skip meals. 

For those wanting to explore intermittent fasting for the first time, I believe that the 16/8 protocol is the easiest and mostly likely to stick for a lot of people. But for most people, planning when to eat or not is in-and-of-itself already stressful. This can lead to even higher cortisol levels, one of the main hormones that we are attempting to balance during fasting. For those who do not “feel off “when there is not food in your belly, perhaps trying the 24-hour fast 1-2 times maximum a week is where to start.

 But above all, I recommend that people fast when it is convenient. That is, skip meals (but NEVER water) when it is convenient, or you find itself “running around” with not time to eat. Just be conscious NOT to do that anymore than twice a week - and do not let that become an excuse for you to not take proper care of yourself. Instead, use it an opportunity to become better aware of your health and the needs of your body.


And lastly:

  1. Proper nutrition becomes even more critical when fasting—choosing wisely which foods to eat needs to be the first step when fasting. Fasting, when followed by highly processed, pro-inflammatory (toxin-rich foods) foods, will do more harm than good. The idea behind fasting is to reboot your system so it can operate more optimally – not to challenge it even further with unhealthy foods.

  2. ALWAYS discuss any changes in your dietary regimen with your primary care practitioner. Remember, Intermittent fasting is not for everyone, especially those with chronic illnesses and cancer. When not adequately supervised, Intermittent fasting can work against your system and the medical regimen you are on rather than help you. 

About the Author:

Dr. Edison de Mello is the founder and Chief Medical Officer of the Akasha Center for Integrative Medicine and Akasha Naturals in Santa Monica, California. He is board-certified by the American Board of Integrative Medicine, and as a psychotherapist by the California Board of Behavioral Sciences.

His recently published book, Bloated? Summarizes Dr. de Mello's three decades of focus in Integrative Medicine, specifically in Gut medicine. His Signature approach to "meeting his patients before meeting their diseases" has received international recognition.

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