Even though we have no control over the genetic aspects of our metabolism, it is possible to speed up the rate at which the body processes calories. A person can increase their metabolism by making healthful changes to their diet and lifestyle (i.e. strength training, high intensity interval training, and reducing stress). Another example is drinking enough water and staying hydrated. Water is necessary for optimal metabolism, and it may help a person lose weight. One study found that adding 1.5 liters of water to the usual daily consumption of water reduced the average weight and body mass index in a group of overweight women aged 18–23.