Some people suggest that following specific diets or avoiding certain foods will help to treat or even cure cancer, but there is no credible evidence to support this claim. It is important that people undergoing cancer treatment eat a well-balanced diet that provides adequate protein, energy and micronutrients to maintain weight throughout cancer treatment. There is no special diet that can “cure cancer” and there is little evidence that following a strict diet will have any added benefit. While some diets may promote useful healthy eating messages, they often include specific and even extreme recommendations about what to eat and what to avoid and why. This advice may have no credible research to support it, or emerging science at best, rather than the overall body of scientific evidence. Some diets suggest people avoid certain food groups entirely (e.g. animal products), which is not necessary nor evidence-based. This can be quite restrictive for people undergoing cancer treatment who may have side-effects that diminish their appetite, lead to nausea and vomiting, or cause mouth ulcers and require flexibility with food choices to obtain the nutrition they need. For more information about what to eat during cancer treatment speak to a dietitian at your hospital or find an accredited practising dietitian through the Dietitians Association of Australia. A dietitian can provide healthy eating advice based on a patient’s medical history, cancer type, specific treatment regime and any other health issues or complicating factors. They will also be able to answer any questions about other dietary regimes and diets. Evidence that ketogenic diets benefit cancer patients, specifically those with brain tumours, is lacking.