Does Fasting Help In Protection Against Cancer?

Can fasting play a role in reducing the risk of cancer or in helping during treatment? Here's what science and experts have to say.

By Sahajiya Halder
04 Feb 2022

Fasting has been a part of our rituals for ages, and different variations of fasting diets have trended over the years, some fads, and some with legitimate benefits. One area where there is growing interest in recent times is the effects of fasting on cancer treatment and prevention.


Intermittent fasting is touted for its many benefits, primary of which is for those looking to lose weight, but some studies have shown that it can also play a role with regards to cancer. A study published in Cell Metabolism showed that a periodic fasting mimicking diet (FMD) showed reduction in cancer incidence in mice, and an associated clinical trial showed decrease in risk factors of age-related diseases. Another study, published in Cancer Cell, showed that a combination of chemotherapy and fasting-mimicking diet can help in delaying the progression of breast cancer and melanoma. A small pilot trial in BMC Cancer suggested that short-term fasting during chemotherapy for breast and ovarian cancer may have beneficial effects on quality of life, although large-scale studies are necessary to prove the effects.


There has not been enough research on this subject, especially on humans, as most are animal studies. Moreover, it is important to note that most of the studies have dealt with intermittent or short term fasting and calorie restriction, and not prolonged fasting. A study published in Nature Reviews Cancer on cancer and fasting mentioned that while studies have shown that cycles of low calorie fasting-mimicking diets are feasible and overall safe, fasting itself is hardly tolerated by patients, and trials are still ongoing. "Fasting doesn't help in cancer treatment. Usually, cancer treatment involves chemotherapy, radiotherapy, and surgery. To tolerate these treatments, a patient needs good nutrition. Usually, we try to increase the calorie intake", says Dr. Sayan Paul, senior consultant oncologist, Apollo Hospital, Kolkata.


"Because of cancer itself and the side effects of the treatment, the appetite decreases, and digestion is not proper. Cancer causes deterioration in nutritional status, which is called cancer cachexia. So our aim is always to increase the food intake and maintain adequate nutrition. Fasting will make the situation more complicated", he continues.


It is crucial to consult your doctor before making any changes in your diet, even as a pre-emptive measure. It is important to keep in mind that not everything is suitable for everyone. Type-2 diabetes and obesity are risk factors for cancer, and a study on mice, published in Cell Metabolism, presented that time-restricted feeding can help in reversing the progression of these conditions. On the other hand, fasting for individuals with diabetes, especially those taking insulin, can lead to extreme lowering of blood glucose levels. Dr. Paul says, "Fasting doesn't decrease cancer risk, but at the same time, obesity is a risk factor for cancer, so a balanced diet is always advisable."


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