The American Cancer Society states that fasting or calorie restriction is not used to treat cancer. ¹⁾ A 2014 systematic review of fifty-nine studies on animals found that 91% showed caloric restriction to play an anti-cancer role during intiation, progression and metastasis of cancer. ²⁾ A 2018 paper warns that “whether the results obtained by fasting in the cellular and animal models can be transferred to cancer patients is still to be ascertained. At the moment, more preclinical studies are required to determine in which cancers, at which stage, and in what combinations fasting, fasting-mimicking diets or caloric restriction mimetics may prove effective.” ³⁾ In animals like mice and monkeys, cancer cells do seem to be sensitive to calorie restriction, except that there are some cancer cells with mutations that make them resistant. “This suggests that the efficacy of CR may be limited to certain cancers.” ⁴⁾

However, it has been shown that fasting can help prevent cancer. ⁵⁾ Fasting is also “promising for improving the efficacy of anticancer therapies and reducing the side effects of cytotoxic treatments”, except for individuals that are at risk for weight loss or have a suppressed immune system. ⁶⁾

A previous version of this article was published on Wikipedia here. More about fasting here.