Studies are being carried out on the 5:2 diet, including with cancer patients, however to date there is no conclusive evidence of the benefits or potential risks. For people having cancer treatment, fasting can put you at risk of not getting enough important nutrients at a time when your body needs plenty of energy, protein, vitamins and minerals to help cope with treatment. Being a healthy weight is an important factor in preventing a number of cancers. Intermittent fasting can reduce a person’s overall energy (kilojoule) intake and so can help some people lose weight. The 5:2 diet involves eating normally for five days of the week and then consuming a strict low energy diet for the remaining two days. It is one of the most common intermittent fasting diets. However, certain groups are advised to avoid this diet, including children, teenagers, diabetics being treated with insulin, and pregnant or breast-feeding women. As the 5:2 diet becomes increasingly popular, more research is expected to appear over coming years. For cancer prevention, we recommend eating a well-balanced diet with a variety of vegetables, fruit and whole grains, as well as some fish, chicken, lean meats, nuts, seeds and reduced-fat dairy foods. We know that this type of a diet, along with regular exercise, helps reduce your risk of cancer. If you are a cancer patient, talk to your GP before making changes to your diet.