Real or Fake News: Intermittent Fasting Fights Cancer Cells?

Intermittent fasting is making news again. This time, it’s within the fight against cancer.

In fact, intermittent fasting (IF), which is a tool used by many people who eat in the Keto Zone, may help prevent, and even fight cancer cells.


It affects cells in many small, healthy ways. These may add up to making cells better at fighting cancer and preventing it in the first place (1).

Here are the basics of intermittent fasting and how intermittent fasting fights cancer cells.

What is Intermittent Fasting?

In simple terms, intermittent fasting is periods and fasting and eating on a regular basis. Most people who use it on a daily basis aiming for a fast of 12-16 hours out of each 24-hour day.

Obviously, this is more fasting time than the typical 8-10 hours allotted by a regular dinner, overnight sleep, and breakfast time.

In order to achieve intermittent fasting, dinner is usually eaten no later than mid-evening and is the last food of the day. Breakfast is often delayed until mid-morning or even noon. A time frame of fasting from about 7:00pm to 11:00 am is a typical fasting window of 16 hours.

Of note, some participants still consume small amounts of no-carb, liquids during the fast. For example, bulletproof coffee may be consumed in the morning. There is plenty of evidence that no or very-low-carb intake mimics fasting physiologically.

Why use Intermittent Fasting?

There are many documented benefits to intermittent fasting.

These include:

  • Improve cholesterol markers
  • Reduced triglycerides
  • Improved aging
  • Weight loss without negative cellular adaptations
  • Reduced risk of Diabetes
  • Reduced risk of cancer and improved treatment tolerance

Intermittent Fasting Fights Cancer Cells in 5 Ways

So, how does intermittent fasting fight cancer cells?

1. Improved Insulin Sensitivity and Blood Sugars

During times of fasting, the body works to make the cell membranes more sensitive to insulin. When there are no fuel sources available in the bloodstream, the body works to become better at metabolizing any it can use.

More insulin sensitivity means more efficient glucose usage and less Diabetes.

Better insulin sensitivity is associated with less cancer cell growth (2, 3).

2. Improved Weight Loss without Plateaus

Intermittent Fasting is an effective weight loss tool.

Of course, when you’re fasting, you’re not consuming calories, so it may be easier to create a calorie deficit. However, the benefits of intermittent fasting on weight loss are beyond calorie deficits.

One issue with long-term normal calorie restriction is that our bodies make adaptations that hinder continued weight loss.

Our bodies do not make these adaptations when intermittent fasting (4).

3. Improved Autophagy and Tumor Suppression

To avoid and fight cancer, we depend on our bodies’ natural cell cycle, including cell growth, cell death, and cell autophagy.

Cellular autophagy is the process by which parts of cells are broken down and then used at a later time. This process is extremely important for overall cellular health and tumor suppression.

Intermittent fasting improves system-wide autophagy leading to many health benefits including tumor suppression (5).

4. Improved Immune Response

Intermittent fasting affects the immune system in many ways.

First, it improves stem cell function. It increases their ability to renew and repair themselves.

In fact, lab studies have shown that fasting correlated with less damaged cells.

Next, intermittent fasting has been found to be effective at reducing autoimmune response and then repairing cells during the re-feeding phase (6).

Lastly, fasting has a beneficial impact on white blood cells, increasing their production to replace ones that are damaged.

White blood cells are especially important during cancer treatment because they are killed in large numbers by most chemotherapy. By increasing white blood cells production and overall immune function fasting can help fight cancer and infections during chemotherapy.

Of note, white blood cell production is actually slightly diminished during the fast itself, but then vastly increased when food is reintroduced.

5. Better Chemotherapy Outcomes and Tolerance

Interestingly, studies have found that fasting for a 72 hour period, beginning 36 hours before chemotherapy, can have a positive impact on chemotherapy tolerance and efficacy.

It seems illogical as one might think a patient would be better off to increase food intake to bolster up energy before treatment.

However, one study found that inflammation and toxicity markers after chemotherapy were reduced when the patient was in a physiologically fasted state (7).

What’s more, fasted patients in studies have reported less negative side effects than those who were not in a fasted state. Mice studies have shown better results with anti-cancer drug treatment in a fasted state than non-fasted (8).

Bottom Line

Intermittent Fasting offers a lot of health benefits to those with, and without cancer. While not a stand-alone cure-all, intermittent fasting fights cancer cells.

It does so by improving insulin sensitivity, weight loss, immune response, autophagy, and chemotherapy tolerance and efficacy. It also has been shown to be safe in humans.

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