3. Fasting-mimicking diets. Valter Longo, a leading longevity researcher at the University of Southern California, has developed a fasting-mimicking diet20 shown to be effective in extending life in animal models, and in weight loss, improving insulin resistance, cholesterol, dementia, autoimmunity, and response to chemotherapy and radiation in cancer patients.21 It is a plant-based diet of 800 calories per day for five days and can be done monthly or quarterly.