There is increasing evidence that lifestyle after the diagnosis of cancer may affect prognosis. Several studies have shown that a Western dietary pattern, obesity, weight gain, a sedentary lifestyle, metabolic syndrome, high serum levels of insulin, growth factors, and inflammatory cytokines after the diagnosis of cancer are associated with an increased incidence of recurrences. Most studies have been on breast and colon cancer. However, in the clinical management of cancer, little attention is presently paid to improving lifestyle and controlling body weight. Lifestyle intervention trials are needed to corroborate or confute the observational results on cancer recurrences, but, even now, there is no contraindication to promoting moderate physical exercise, moderate calorie restriction (CR), and a Mediterranean dietary pattern. In fact, the AICR/WCRF 2007 systematic literature review recommends cancer patients to adopt the lifestyle recommended for the prevention of cancer. Interestingly, the evidence-based AICR/WCRF recommendations coincide with traditional rules, based on far Eastern philosophy, of avoiding extremely yin food, such as sugared beverages and calorie-dense foods, and extremely yang food, such as processed meat, and relying on the equilibrium of slightly yang food, such as whole-grain unprocessed cereals, eaten with slightly yin food, such as legumes and vegetables.