Metabolism. Simply put, it’s the process by which the body makes and uses energy (calories) for everything from the cellular absorption of nutrients to running a marathon.Sounds like pretty boring science on paper. Except that knowing how to efficiently metabolize calories could translate into a healthier body.Whether you’re trying to lose extra pounds or preparing for the inevitable metabolic slowing that comes with age, here are some surefire ways to boost your metabolism to keep your energy pulsating and your body in shape.1. Build lean body mass. As mentioned above, metabolism slows as we age – by as much as two percent a year! But there is something you can do to counterbalance nature. "Muscle is the single most important predictor or how well you metabolize your food, how well you burn calories and burn body fat," insists Shari Lieberman, author of Dare to Lose. Strength training with dumbbells or resistance bands at least twice a week is essential to boosting your metabolism. Repeat – essential. And here’s the really good news: Your metabolism stays pumped for many hours after you finish your workout.2. Get moving. You know the drill, but here’s a reminder. At least 30 to 60 minutes of walking, jogging, cycling, swimming or some other form of aerobic exercise a minimum of three times a week is the other half of the exercise equation. "People don’t like to hear it but you have got to exercise," says Lieberman.3. Eat. It may sound crazy to those trying to lose weight by severely restricting their daily caloric intake, but the problem with this old school of thought, explains Michigan dietician Julie Beyer, is that it actually slows metabolism. "Every cell of the body is like a flashlight bulb," she explains. "When our bodies don’t get enough food, or fuel, every cell burns less brightly." Recent studies show that eating smaller meals every three to four hours aids metabolism and weight loss.4. Ditch the sugar. Of course, you still have to make good choices about what you eat. "When you eat sugar you throw your metabolic switch into fat storage mode," says Lieberman, who suggests a predominately low glycemic index diet, meaning foods that, unlike sugars, are broken down gradually to help maintain an even blood-sugar level. 5. Don’t skip breakfast. It’s a fact that people who eat a healthy breakfast are skinnier than people who don’t. And try to think outside the box. A breakfast bowl of vegetables and brown rice is a great way to kick-start your metabolism for the day.6. Include hot foods. If Mexican and Thai are favorites, you’re in luck. "Spicy food that has hot peppers in it appears to boost metabolism," Lieberman says. 7. Drink green tea. "There are unhealthy things that can boost your metabolism, like a really strong cup of coffee, or nicotine, but I would never say go have a cigarette!" says Michelle Streif, a personal trainer in Nebraska. Nor overdo it on caffeine, which also has undesirable side effects. Instead, go for green tea, says Lieberman, which is known to stimulate metabolism longer and more effectively than coffee. 8. Don’t forget H2O. Staying well hydrated is essential to flushing the body of toxic byproducts that are released when fat is burned. Cold water may also give your metabolism at least a small boost because energy is required to heat the body.9. Avoid stress. At all costs. "Stress can actually cause weight gain, particularly around the tummy," says Lieberman. Why? Because physical and emotional stress activates the release of cortisol, a steroid that slows metabolism.10. Sleep. Research shows that people who don’t sleep for seven to eight hours a night are more prone to weight gain. Additionally, we now know that lean muscle is regenerated in the final couple of hours of sleep each night, says Beyer. Which takes you right back to tip number one!