Your metabolism - the rate at which you burn calories - plays a major role in how successfully you manage your weight.
There are three major components of total metabolism:
1. VITAL BODY FUNCTIONS - such as breathing, heart rate, brain functioning - account for a whopping 60 -75% of your daily caloric expenditure. Your resting metabolic rate (RMR) measures the energy you use to maintain these functions.
2. ACTIVITY - the energy you use for work, exercise and daily living - accounts for 20-30% of your daily caloric expenditure.
3. DIGESTION accounts for 5-10% of your daily caloric expenditure.

So basically..  Increase muscle mass to increase RMR and eat small meals often! and exercise