This 2017 review summarizes the potential of a ketogenic diet to enhance the effects of radiotherapy. Radiotherapy is constrained by the damage it causes to healthy cells. As a result, any simultaneous treatment that can either increase the damage radiotherapy does to cancer cells or protect healthy cells from damage may increase its effectiveness. Potential benefits of a ketogenic diet alongside radiotherapy include the reduction of cancer cells’ ability to repair DNA, the slowing of tumor growth and repopulation, and the protection of healthy cells against the harms of radiotherapy by shifting them from an anabolic/growth-centric state to a non-dividing state.