There are also other means of controlling metabolism than merely the hormonal balance you inherit from your parents. A person can speed up their metabolism by choice with increased levels of exercise, or by eating more meals per day, at more regular intervals, and in smaller portions. This is the basis for all successful diet plans - controlling calorie intake and burning more of them. Muscle burns more calories than fat, so a generally good fitness level will result in a faster metabolism.
In addition, a faster or slower metabolic rate is sometimes the side effect of a particular medicine you may be taking, or as a result of hormone replacement therapy, commonly prescribed for post-menopausal women. The intake of other drugs, such as nicotine, caffeine, or illegal stimulants such as cocaine also speed up the body's metabolism.
Metabolism is based of your natural genetics and there isnt much you can do to speed the change of it but click on the link and theres an interesting article
Metabolism is the sum of all the chemical processes by which the cells in living things produce the material and energy required to sustain life. These processes are classified in two phases - anabolism and catabolism. During anabolism cells combine molecules to assemble new organic materials, and during catabolism the cells break down molecules to obtain energy and release heat. All organisms are engaged in both phases constantly.
The rate of anabolism as well as catabolism is controlled by hormones. A hormone called thyroxine secreted by the thyroid gland determines the rate of metabolism. Other hormones secreted by pancreas determine the relative rate of metabolism and catabolism. The basic rate of metabolism when a person is at rest, called the basal metabolic rate (BMR), varies among people according to sex, age, and body size. disorders of the thyroid and other glands also affect the rate of metabolism.