The document discusses different methods of intermittent fasting, including the benefits and potential downsides. It describes four popular intermittent fasting methods: the 16:8 method which involves fasting for 16 hours and an 8 hour eating window; the 5:2 method where one eats normally for 5 days and restricts calories to 600 or less for 2 days; Eat Stop Eat which involves extended fasting periods; and alternate day fasting where one fasts every other day. The document stresses that intermittent fasting methods may cause initial mood swings or increased cortisol until the body adapts.