In one study of time-restricted feeding during 9–12 hour phases, fasting was shown to reverse the progression of obesity and type 2 diabetes in mice. Obesity is a major risk factor for cancer, which may support fasting to treat cancer.

A second study of mice showed that a bimonthly fasting-mimicking diet reduced the incidence of cancer. Results were similar in a pilot trial by the same scientists with 19 humans; it showed decreased biomarkers and risk factors for cancer.

In a 2016 study, research showed that a combination of fasting and chemotherapy slowed the progression of breast cancer and skin cancer. The combined treatment methods caused the body to produce higher levels of common lymphoid progenitor cells (CLPs) and tumor-infiltrating lymphocytes. CLPs are the precursor cells to lymphocytes, which are white blood cells that migrate into a tumor and are known for killing tumors.

The same study noted short-term starvation makes cancer cells sensitive to chemotherapy while protecting normal cells, and it also promoted the production of stem cells.