Adding interval training — bursts of high-intensity moves — to your workout is a great metabolism booster. "Studies have shown that people who do interval training twice a week [in addition to cardio] lose twice as much weight as those who do just a regular cardio workout," says obesity specialist Aronne. You can easily incorporate interval training into your workout by inserting a 30-second sprint into your jog every five minutes or by adding a one-minute incline walk to your treadmill workout. "Since your body is working harder, it's a more intense workout -- and you therefore burn more calories," says Westcott. On other days, shake up your routine with 40 minutes of cross-training. Ideally, aim for two 20-to-40-minute interval-training sessions and two 20-to-40-minute cross-training sessions a week.
Skimping on sleep can derail your metabolism. In a study at the University of Chicago, people who got four hours of sleep or less a night had more difficulty processing carbohydrates. "When you're exhausted, your body lacks the energy to do its normal day-to-day functions, which include burning calories, so your metabolism is automatically lowered," explains Peeke.