A permanent routine of exercise, eating healthily, and, during periods of being overweight, consuming the same number or fewer calories than used will prevent and help fight obesity. A single pound of fat yields approximately 3500 calories of energy (32 000 kJ energy per kilogram of fat), and weight loss is achieved by reducing energy intake, or increasing energy expenditure, thus achieving a negative balance. Adjunctive therapies which may be prescribed by a physician are orlistat or sibutramine, although the latter has been associated with increased cardiovascular events and strokes and has been withdrawn from the market in the US, the UK, the EU, Australia, Canada, Hong Kong, Thailand, Egypt and Mexico.