Spice up lunch with peppers. Capsaicin, the key substance that makes chili peppers hot, stimulates your "fight or flight" stress response and may increase metabolism by 23 percent. Peppers may even improve your muscle-to-fat ratio: Research suggests that capsaicin inhibits the generation of fat cells.
Sip a cup of green tea. This miracle beverage pairs caffeine with a compound known as EGCG—and together they create an even greater bump in metabolism than caffeine alone. Studies also indicate that green tea may reduce body fat and trim the waistline.
Use your muscles—with your mind. Believe it or not, visualizing a workout can actually trick your body into strengthening your calorie-zapping muscle: A Cleveland Clinic study discovered that participants who spent 15 minutes a day imagining flexing their biceps had a 13.5 percent increase in their strength after three months.