Metabolism is the rate at which your body uses energy and expends calories. It involves a series of biochemical processes through which your body converts food into fuel for the cells in your body. So it stands to reason that if you speed up your metabolism, weight loss will be easier, right? The reality is not that simple.

The biggest factor in whether someone gains or loses weight is not metabolism. Your weight loss primarily hinges on your body's daily energy balance — how many calories you are taking in every day vs. how many you are expending.

"What determines whether you're gaining or losing weight is whether you're eating more calories than you're burning," says Michael Rosenbaum, MD, associate professor of clinical pediatrics and clinical medicine at Columbia University Medical College in New York. "Burning more calories through exercise will allow you to eat more or lose more weight."

Exercise and diet boost your resting metabolic rate, which is the rate at which your body burns calories every day just through the process of staying alive. By boosting your metabolism, you increase the amount of calories you burn during rest or normal activity, which aids in your weight loss. Resting metabolic rate also plays a large role in keeping lost weight off. But ultimately exercise and diet are what determine how much you weigh.

Boosting Your Metabolism: Diet

Diet can have a large impact on your metabolism, but only if you keep eating. Cutting back the amount of food you eat through a fad diet or skipping meals can send your body into fat-storing starvation mode, slowing down your metabolism and hindering your attempts for lasting weight loss.

To keep your metabolic rate up, you should:

  • Eat breakfast, which gives your body an early energy boost and deters it from fat storage.
  • Eat many small meals and snacks throughout the day to keep your metabolism busy burning fuel all day long.
  • Increase the amount of lean protein you eat. Your body burns more calories when it is digesting proteins, compared with carbohydrates and fats.

Boosting Your Metabolism: Exercise

Aerobic exercise provides your metabolism a temporary boost, but it only lasts for a short time after the exercise has ended. The main role of aerobic exercise is to burn calories and influence your body's daily energy balance.

Strength training is the form of exercise that can have an influence on your resting metabolic rate. Increasing your muscle mass increases your metabolism. In fact, that's why your metabolism winds down as you get older: as you age, you lose muscle. While muscle and fat weigh exactly the same on the scale, muscle is compact tissue and it is also active tissue — it burns calories.

Activities that naturally boost your metabolism — strength training and eating lean protein — contribute to weight loss. But keep in mind that when you stop these activities, your body will revert to its original metabolism. To keep the weight off, you need to adopt healthy habits that you will be able to live with for a long time.

Learn more in the Everyday Health Weight Center.