For those potentially concerned about cancer risk from breaking fasts, from the article itself:

> Researchers should always be concerned about anything that could cause cancer, but Valter Longo, a biogerontologist at the University of Southern California in Los Angeles, says that mice with the tweaked genes were “almost doomed to get cancer”, and that the slight rise in risk found in this study might not be applicable more broadly. For example, he points to a study he published in 2015 that found a 45% reduction in abnormal cell and tissue growth in mice that fasted compared with animals that did not.

The mice that developed precancerous growths were genetically modified to be prone to such cancerous development.