How Exercise Affects Your Metabolism

How Exercise Affects Your Metabolism

Most people think that "doing exercise" will help to speed up their metabolism. However, this vague statement--while mostly true--needs to be dissected a bit more in order for you to understand how you can make your metabolism work for you with exercise.

The Ways to Burn Calories

The word "metabolism" essentially means "burning calories to give your body the energy it needs." And there are three ways that your body burns calories:

1. The resting metabolic rate (RMR): Your RMR accounts for up to 75 percent of the energy you burn every day. Your body needs to supply your organs with energy even while you do nothing, and that's what your RMR is: the calories your body burns while in rest. It's the energy you burn while sitting, sleeping, standing, etc.

2. The thermic effect of food (TEF): When you eat, your body has to turn up the heat in your digestive system in order to process the food. It requires more energy than when you're sitting with an empty stomach. The TEF usually accounts for no more than 10 percent of the energy that you use in a day.

3. The physical activity energy expenditure (PAEE): This is any energy that is burned while you are working out or doing any kind of activity. Whether you're washing dishes, walking up the stairs, picking up a box, or lifting hundreds of pounds of weight, this is the PAEE. It's all dependent on your movement (activity) during the day.

The amount of energy that you burn in a day is the sum total of these three calorie-burning methods.

So, how does exercise affect your metabolism?

The Effects of Exercise on Your Metabolism

The PAEE is always directly affected by the amount of activity you do in a day. The more exercise you do, the more calories are burned by this expenditure. Increasing the number of calories you burn via PAEE is one way to speed up fat burning.

However, the question remains: "Do I burn more calories after exercising?" This is where your exercise affects your resting metabolic rate, your RMR.

When you lift weights, run, jog, walk or use your muscles, your body uses up the glucose it has stored in those muscles. It takes energy (calories) to replenish the glucose in those muscles, so doing exercise burns energy (calories) in the muscles as well as the energy that your body uses to refuel the muscles.

With exercise like cardio or endurance training you use very little glucose--instead focusing more on burning fatty acids (fat). This means that the body doesn't need to restore the glucose, so there is very little need for refueling AFTER the workout. This is why low intensity, endurance, and steady state training DO NOT raise your RMR.

On the other hand, if you do high intensity exercise or lift weights, you use up all of the glucose in the muscles being used. This means that the body has to send a lot more fuel to the muscles, which takes longer. The amount of time it takes to refuel your body varies from person to person, but during the time that it is refueling, your RMR is increased - turning more food into energy (calories).

So What Does this Mean?
Simple: if you want to increase your metabolism (RMR, in this case) do exercises that drain the muscles of glucose rather than fatty acids. This means any high-intensity exercise or strength-training workout. You'll increase your metabolism for much longer after you're done working out.