Pump IronNot only does lifting weights burn   calories, but by increasing lean muscle mass, you increase metabolism, because   a pound of muscle burns up to nine times the calories of a pound of fat.

Drink Green Tea Studies show that people who   consume a green-tea extract three times a day increase their metabolic rate   by 4 percent. That adds up to 60 calories a day — or six pounds a year.

Do Interval Training If you typically run 10-minute   miles, add 30-second sprints every 5 minutes. On the treadmill, mix in 1 minute   of incline work every 5 minutes; the added intensity will boost metabolism.

Chill Out! According to studies, stress promotes   production of hormones like cortisol, which stimulates appetite, slows metabolism,   and encourages fat storage. Instead, reduce stress by doing yoga or meditating.

Get More Iron Iron deficiency reduces your body's   ability to get oxygen to your cells, which slows metabolism. Instead, take a   multivitamin or eat iron-rich foods, such as lean red meat, chicken, or fortified   cereal.