Time to Eat
Intermittent fasting (IF) has been proven to affect glucoregulation, inflammation, obesity, and sleep—all of which can decrease breast cancer risk. But how exactly does it work?

Intermittent fasting (IF) is a new “diet” taking the health and wellness world by storm. Also known as “time-restricted eating,” calling IF a diet isn’t quite accurate, because it’s not about what you eat, but when.

So, how long can one go without eating? An IF diet plan consists of a period of eating offset by a period without calorie consumption, and has been shown to positively influence prognoses of breast cancer. In an August 2016 study in JAMA Oncology, nearly 2,500 women fasted overnight for a 13-hour period. According to the study, nightly fasting may be a simple, non-medical strategy for reducing the risk of breast cancer recurrence.

In the study, half of the participants fasted for more than 12.5 hours per night, and half fasted for less than 12.5 hours per night. The study found that those who fasted fewer than 13 hours a night were associated with a 36 percent higher risk of breast cancer recurrence. Although there is limited data on the association between time-restricted eating and tumor growth, the study says: “In rodents, calorie restriction is an effective way to reduce cancer and cancer-related risk factors, and studies suggest that intermittent calorie restriction prevents mammary tumor development to a similar, or even greater, extent than chronic calorie restriction.”

But how does breast cancer play into this? In an August 2014 column, Dr. Marisa Weiss, the founder, president, and chief medical officer of, said overweight and obese women have a higher risk of developing breast cancer and a higher risk of recurrence, “especially if they carry extra fat in their midsection.” Extra fat cells make extra hormones that lead to extra breast cell growth. “When you have higher levels of these hormones in your blood over time, the risk of cancer is increased,” Weiss writes.

Hormones are also closely related to our natural circadian rhythm. An article by Satchin Panda, Ph.D., published by the University of California, San Diego, in September 2018 examines research about this rhythm. According to Panda, these “internal clocks” control things like falling asleep, signal hunger cues, and affect how we fight disease. “The timing of eating is like an external time cue that signals the internal circadian clock to keep a balance between nourishment and repair,” writes Panda. During a fast, the metabolism is geared towards “rejuvenation,” meaning unhealthy chemicals are broken down, fat is burned, and damaged cells are repaired. When we go off a fast, the metabolism is more focused on nourishment, meaning our bodies are better able to absorb nutrients, using or storing them more effectively.

The timing of eating is like an external time cue that signals the internal circadian clock to keep a balance between nourishment and repair.

-Satchin Panda, Ph.D.

One of the examined studies, published by the journal Cell Metabolism, placed mice on a time-restricted eating schedule and found that regardless of diet, the mice remained healthy and did not succumb to disease. This might be confusing, because it is well-documented (including in issue 2 of cW) that sugar is cancer’s preferred food. According to Dr. Anna Cabeca, a board-certified OB-GYN and author of “The Hormone Fix,” reducing the amount of glucose, or sugar, circulating in the body is imperative to stave off cancer. “IF helps us do that,” Cabeca says.

Cabeca considers widespread insulin resistance an “epidemic situation” in this country, common due to the highly processed foods we eat. Insulin resistance results in our bodies needing more insulin to reduce the amount of circulating glucose, and can cause cardiovascular disease, diabetes, polycystic ovarian disease, and worse menopausal symptoms, among many other effects. But luckily, according to Cabeca, following an IF diet can create insulin sensitivity.

Most simply, time-restricted eating promotes autophagy—healthy cell regeneration—because our bodies adapt to a certain pattern of eating and becomes better regulated at storing glucose. “Our bodies [are able] to get into this state [of] taking out the garbage, essentially cleaning up the unhealthy cells,” Cabeca says.

Cabeca likens cancerous cells to a neighborhood. “Good neighbors have good boundaries and communicate with each other, but yet hold healthy boundaries,” Cabeca begins. “If something’s going wrong, like your dogs are running loose, [a good] neighbor will help you out, [but] if you’re a bad neighbor, all of a sudden you’re going downhill—your weeds are overgrowing [and] that affects the neighbor next door. […] That kind of seeps through the neighborhood, [destroying] one cell after the next cell after the next cell.” IF can help create healthy cells who can communicate with each other. “Cell-to-cell communication is key,” says Cabeca. “When you have damaged cells, they don’t communicate well.” This can lead to cancer.

It’s easy to make IF part of your life. Typically, time-restricted eaters fast overnight, maintaining at least a 13-hour fast. The average 2,000 calorie diet could be followed, but many fasters see weight-loss results by combining a fasting schedule with a lower-calorie diet rich in whole foods and with limited intake of sugar, unhealthy fats, and simple carbohydrates.

“Intermittent fasting, no snacking, and lots of plant-based nutrients, as well as lifestyle factors that reduce (the stress hormone) cortisol, [like] meditation, getting out in nature,” begins Cabeca. “All of those things decrease our risk of cancer and improve our longevity.” Eat well, fast often, and reduce your risk of cancer.


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