Intermittent Fasting and Cancer
Over the past decade, there has been increased scientific interest in fasting and its relationship to chronic disease, including cancer. There is emerging evidence that intermittent fasting has positive effects on metabolism, decreases cellular growth signaling pathways and reduces inflammation in the body. Different protocols for intermittent fasting have been developed, and it is still not clear which populations would benefit most from fasting, how long to fast for, or how frequently.
Some patients report decreased side effects when they fast around chemotherapy infusions. Several small clinical trials have found that patients with a variety of cancer types experience fewer chemotherapy-related side-effects from fasting for several days before, during and/or after chemotherapy infusions. However, the long-term benefits of fasting on tumor control are not yet known. Additionally, a clear protocol for how thoroughly to fast, or for how long, has not been defined. In general, one to three days of fasting around chemotherapy should only be attempted if you are not at risk of losing weight, not underweight, not at risk of malnutrition or protein deficiency, are not elderly, are not taking medications for diabetes, and if your chemotherapy infusions are spaced out at least 3 weeks apart. Ideally, it is best to discuss the risks and benefits of fasting and chemotherapy with a trusted health care provider or registered oncology dietician who knows your medical history well.
There is some evidence that long nighttime fasting might reduce cancer recurrence rates in people with a history of breast cancer. Over 2000 patients with a history of breast cancer were followed for 11 years to evaluate their risk of breast cancer recurrence. Women who routinely fasted overnight for 13 hours or more had a reduced risk of breast cancer recurrence. For example, stopping eating at 7 pm and not eating again until 8 am the next morning would be a 13 hour overnight fast. A similar study found that women who fasted for long periods overnight had improved blood glucose after eating and lower blood sugar control in general.
