Fasting and Breast Cancer

We all know someone who is or has dealt with breast cancer. I wanted to provide some information related to Intermittent Fasting (or “Time Restricted Feeding”) to help prevent breast cancer. I will begin with two brief video excerpts, but be sure to watch the entire podcast interview by Dr. Rhonda Patrick with Dr. Ruth Patterson below. – Bobby

Added: 10/13/2017 12:30 PM

Breast Cancer and Fasting:

In patients with breast cancer, a short overnight fast of less than 13 hours was associated with a statistically significant, 36 percent higher risk of breast cancer recurrence and a non-significant, 21 percent higher probability of death from the disease compared to patients who fasted 13 or more hours per night, report University of California, San Diego School of Medicine researchers.

The study, published online in the Journal of the American Medical Association Oncology on March 31, also found a non-significant, 22 percent higher risk of mortality from any cause among patients with breast cancer who fasted for shorter periods compared to those who fasted for 13 hours or more overnight.

Researchers also reported that fasting fewer hours per night was associated with significantly less sleep and higher levels of glycated hemoglobin (HbA1c), which is a measure of average blood sugar levels over a period of months. These findings are relevant to cancer prevention and control efforts because elevated HbA1c and poor sleeping habits have been linked to an increased risk of breast cancer. These findings corroborate a paper published in April 2015, in which researchers demonstrated that shorter overnight fasts were associated with worse blood sugar control.

“Prolonging the overnight fasting interval may be a simple, non-pharmacological strategy for reducing a person’s risk of breast cancer recurrence and even other cancers,” said Catherine Marinac, lead author and doctoral candidate at UC San Diego Moores Cancer Center. “Previous research has focused on what to eat for cancer prevention, but when we eat may also matter because it appears to affect metabolic health.

The study included 2,413 non-diabetic breast cancer survivors between the age of 27 and 70 who participated in a multi-institutional research study conducted between 1995 and 2007, with follow up for breast cancer recurrence and mortality. Participants were 86 percent non-Hispanic white and 55 percent were college educated.

“If future trials confirm that habitual prolonged nightly fasting improves metabolic health, this would be an important discovery in prevention that could reduce the risk of cancers, type 2 diabetes, and cardiovascular disease,” said Ruth Patterson, PhD, senior author and leader of the cancer prevention program at Moores Cancer Center.


Study: Prolonged Nightly Fasting and Breast Cancer Prognosis –

Metabolism and Breast Cancer:

Added: 9/19/2017 11:00 AM
Prolonged Nightly Fasting and Breast Cancer Risk: Findings from NHANES (2009-2010)

“Breast cancer is the most common form of cancer and the leading cause of death among women in industrialized countries. According to data from the Surveillance, Epidemiology, and End Results (SEER) Program, an estimated 232,670 women in the United States will be diagnosed breast cancer in 2014, and 44,000 will die from the disease.” […]

“There is mounting evidence suggesting that time-restricted feeding, the practice of consuming ad-libitum energy within a restricted window of time and fasting thereafter (upwards of 12-16 hours), has favorable effects on glucose metabolism and may reduce the risk of chronic diseases such as diabetes and cancer. In particular, synchronizing feeding/fasting regimens with daily circadian rhythms (e.g., eating at night for nocturnal mice) appears to reset the body’s peripheral clocks, resulting in improved oscillations in circadian clock gene expression and enhanced energy metabolism (12). A 2014 review by Rothschild and colleagues (13) identified four published studies that have examined the impact of time-restricted feeding on glycemic control in mice (14-17). Regimens of time-restricted feeding favorably influenced fasting glucose in all but one study (14). There is also evidence that fasting regimens have direct effects on cell proliferation (18-20). For example, a study examining the effects of different treatment regimens in mice injected with a variety of cancer cell types (including breast cancer 4T1 cells), found that a treatment regimen consisting of repeated fasting cycles resulted in reduced cancer metastases (20). The authors of this study reported that the therapeutic effects of repeated fasting cycles were as effective as (if not superior to) chemotherapeutic treatments in mice.”


A novel line of research has emerged suggesting that daily feeding-fasting schedules that are synchronized with sleep-wake cycles have metabolic implications that are highly relevant to breast cancer. We examined associations of nighttime fasting duration with biomarkers of breast cancer risk among women in the 2009-2010 U.S. National Health and Nutrition Examination Survey.

Dietary, anthropometric and HbA1c data were available for 2,212 women, and 2-hour postprandial glucose concentrations were available for 1,066 women. Nighttime fasting duration was calculated using 24-hour food records. Separate linear regression models examined associations of nighttime fasting with HbA1c and 2-hour glucose concentrations. Logistic regression modeled associations of nighttime fasting with elevated HbA1c (HbA1c = 39 mmol/mol or 5.7%) and elevated 2-hour glucose (glucose = 140 mg/dL). All models adjusted for age, education, race/ethnicity, BMI, total kcal intake, evening kcal intake, and the number of eating episodes per day.

Each 3-hour increase in nighttime fasting (roughly one standard deviation) was associated with a 4% lower 2-hour glucose measurement (ß 0.96, 95% CI 0.93-1.00; p<0.05), and a non-statistically significant decrease in HbA1c. Logistic regression models indicate that each 3-hour increase in nighttime fasting duration was associated with roughly a 20% reduced odds of elevated HbA1c (OR 0.81, 95% CI 0.68, 0.97; p<0.05) and non-significantly reduced odds of elevated 2-hour glucose.

A longer nighttime duration was significantly associated with improved glycemic regulation.”

Frequency and Circadian Timing of Eating May Influence Biomarkers of Inflammation and Insulin Resistance Associated with Breast Cancer Risk

“There is compelling evidence that persistent low-grade inflammation is a significant underlying contributor to numerous cancers [1–4] (including breast) and is associated with several chronic metabolic conditions linked to breast cancer (e.g., obesity, diabetes) [5, 6]. Laboratory studies have demonstrated that chronic inflammation predisposes tissue to cancer development, whereby tumors generally arise within inflamed tissues [7]. Consistent with this evidence, data from epidemiologic cohorts of women have shown that elevated C-reactive protein (CRP), a biomarker of systemic inflammation, is associated with breast cancer risk [3, 4]. For example, a case-control study among postmenopausal women enrolled in the Multiethnic Cohort Study (706 cases; 706 controls) found that women in the highest quartile of CRP were significantly more likely to develop breast cancer than women in the lowest quartile (OR: 1.41; 95% CI 1.01–1.96; Ptrend = .01) [4].

Insulin resistance is another metabolic condition that appears to play a significant role in the etiology of breast cancer and related metabolic diseases. Although the exact mechanisms linking insulin resistance to these conditions are unknown, experimental data indicate that elevated circulating insulin within the hyperinsulinemic range is a fundamental component of these links [8, 9]. For example, in a sample of women enrolled in the Women’s Health Initiative Observational Study, investigators found that women in the highest tertile of baseline insulin had nearly double the risk of breast cancer relative to women in the lowest tertile (HR: 2.22; 95% CI 1.39–3.53) [9]. The authors of this study also reported that the estimate of breast cancer risk based on insulin was even higher in the subsample of women who did not use hormone replacement therapy (HR: 3.15; 95% CI 1.61–6.17). Insulin resistance is also a hallmark of type 2 diabetes and type 2 diabetes risk [10], and has been associated with numerous other cancers such as liver, kidney, and pancreatic cancer [11].

Recent evidence suggests that dietary behaviors such as eating frequency and timing influence insulin secretion and systemic inflammation, may have downstream effects inflammation and insulin resistance. The majority of this initial evidence has come from mechanistic studies in animals. Landmark studies in rodents have demonstrated that eating regimens that restrict food intake to within a 4- to 8-hour window of time (i.e., ‘time-restricted feeding’), thereby increasing the number of hours spent fasting, can improve metabolic processes related to insulin resistance and inflammation. Specifically, mice subjected to these feeding-fasting regimens appear to be protected from hyperinsulinemia, hepatic steatosis, and inflammation [12]. Notably, the most profound effects of these feeding-fasting regimens on metabolism seem to occur when synchronized with daily sleep-wake cycles (i.e., eating only during the night and fasting during the day for nocturnal mice) [13].”


Dr. Rhonda Patrick’s podcast interview with Dr. Ruth Patterson, Ph.D. on Time-Restricted Eating in Humans & Breast Cancer Prevention:

Discussed in this podcast:

•The importance of time-restricted eating as a practical public health intervention, mostly for it’s ease of implementation, that may have a widespread impact on disease risk.

•Why you should probably make sure your time-restricted eating window occurs earlier in the day, rather than later.

•How the first 5% drop in weight loss can have disproportionately large effects on the metabolic factors associated with breast cancer risk when compared with subsequent weight loss.

•The association of longer fasting durations beginning earlier in the evening and improved sleep in humans, as well as spontaneous physical activity in their day-to-day lives.

•The relationship between metabolism and breast cancer risk.

•The effect of lifestyle factors, such as obesity, physical activity, what and even when you eat, whether or not you smoke tobacco… and how even modest changes, such as consuming food earlier in the day and only during an 11-hour window, can decrease breast cancer risk and recurrence by as much as 36%.

•The importance of starting your fast earlier in the evening, and how an earlier eating window has been shown to correlate to reductions in inflammatory markers.

•The association of higher circulating insulin levels with breast cancer risk, and how insulin itself has an important relationship with estrogen by affecting the levels of sex-hormone binding globulin.

•The dangers of having a cellular environment that is inflamed, as the case is with the obese, and simultaneously having elevated cellular growth signals, which is also characteristic of the hormonal milieu of the obese.

•The surprisingly small role heredity plays in determining overall risk of breast cancer when compared to lifestyle factors.

•How healthful lifestyle habits, like choosing to eat during the right window, ultimately helps us trend our risk for many of the diseases of old age in the correct direction instead of influencing only one or another.