I set out a few months ago to lose a few pounds by changing my metabolism. I've always worked out, stretching, weights, walking, floor work, etc., so it was a matter of increasing those activities and adding more cardio. I chose Zumba (aerobic street dancing) and kickboxing. Also started doing pilates. Usually, I did one or two one-hour classes during the day 5+ days per week plus an additional one-hour class in the evening 4 nights a week - so working out 2 - 3+ hours 5 - 6 days per week, plus 18 holes of golf a couple times per week.
My diet is high-fiber, lots of fruit, veg, lean protein, no bread, very little starch. Gave up alcohol for 3 weeks. Nothing radical. I steadily lost a pound per week for three months - a total of 13 pounds. Here's the great part - even though I've pulled back on the exercise routine a bit (never intended to keep up that pace permanently!) and relaxed my diet a bit, I have maintained my weight loss - which is why I think I actually changed my metabolism. I will be doing this routine periodically so as to maintain the weight loss.