Fasting for cancer Original paper

Fasting — especially intermittent fasting — shows a good deal of promise for a number of health benefits, including a reduced risk of cancer.

This overview of the evidence on fasting as a cancer treatment looks at hormonal, molecular, and cellular responses to fasting; the use of fasting in conjunction with chemotherapy; and current issues. It also suggests lines of research for the future.

Fasting lowers insulin and IGF-1 and raises glucagon, cortisol, growth hormone, catecholamines, and eventually ketones. Broadly speaking, these metabolic changes promote cellular processes associated with apoptosis, autophagy, DNA repair, genomic stability, the detoxification of carcinogens, and a reduction in oxidative stress, all of which can have antitumor effects.

In randomized controlled clinical trials and animal studies that combined fasting with chemotherapy, fasting decreased disease progression and increased remission, probably in part by decreasing the toxicity and increasing the efficacy of chemotherapy.

This preliminary evidence is promising, although further research is required to understand which metabolic pathways are implicated in specific cancers, what factors make fasting more or less effective, and if the benefits derive from not consuming calories or not consuming specific nutrients.

While several ongoing randomized controlled trials will help ascertain if fasting can improve outcomes in cancer patients, understanding its effect on cancer risk will be much harder. Studying fasting for a short time in cancer patients is (relatively) simple, but exploring how fasting affects cancer risk over a person’s entire life is quite another matter. We aren’t likely to see lifelong randomized controlled trials, but high-quality prospective cohort studies may provide some insight.