I just posted this on a post you commented on recently but limit your gluten or cut it out completely! It WILL help. I recommend doing some research on it. Its really not hard to do at all :-)
Metabolism is impacted by a multitude of things, but above all others is motion. MOVE! Our bodies are developed to be moving a majority of the day, and moving at a variety of paces throughout the day.
So, add fitness wherever you can. Bike to work, walk during lunch, do the office exercises here on Workout Trainer during your 15s, take the stairs. You don't need to break a sweat. Just get your heart rate up.
Take it up a notch whenever possible. Do some intervals on the ride home, weight train with a friend or significant other, go dancing, play a sport, or anything else that gets your heart really going. Mix it up.
Diet is important, but motion is what drives progress.
People are confusing metabolism with energy expendature. Start eating foods low in kcals and higher in nutritional value. As a tip. Cut out grains from breakfast and lunch. Will make it easier to stay low in kcals.