Muscle & Metabolic Rates

Before you read this, if you’re not really sure what your metabolism is you can read about it in a previous entry here.

Muscle is referred to as metabolically active. The more muscle you have, the more mitochondria (or energy producing powerhouses) you have. And as such, the more calories you burn – even while at rest. Muscle is the only tissue in the body that has the capacity to burn calories. As such, increasing muscle tissue by strength training is a surefire way to increase or speed up your metabolism. This is why people state that strength training helps you burn fat. It does. Muscle tissue has the capacity for cellular respiration, whereas other tissues found in the body, say fat tissue, do not have mitochondria and as such, does not burn calories. And muscle requires more energy just to maintain; in fact 1 pound of muscle requires approximately 50 Calories a day to just be. Think about this for a minute. 50 Calories a day is 18,250 Calories a year. We know it takes approximately 3500 Calories to burn a pound of fat. If you built up just 1 additional pound of muscle tissue, your body would burn just over 5 pounds of fat each year while resting. Now imagine if you built up 5 pounds of muscle, or even 10!

Frequency of Food Intake & Metabolic Rates

Despite many old wives tales there is little factual evidence to support the idea that eating more small meals a day, over less frequent larger meals, speeds up your metabolism. For some people, eating smaller meals more frequently may help them feel satiated, especially when under-eating for one reason or another. What studies do show is that consistency matters. In terms of meal frequency, each day should look similar to the last. Your body likes and learns to rely on patterns. When we eat every 4 hours one day, every 2 hours the next, followed by every 8 hours the day after, our production gets discombobulated – for lack of better words. This is not ideal for the most efficient use our body’s metabolic engines. There is evidence to support eating certain foods (carbohydrates and proteins) around workouts is beneficial, however this has more to do with providing the nutrients required for the activities, and supporting the recovery process afterwards than that of metabolic rates, and as such we’ll talk about this a bit later.

Exercise & Metabolic Rates

We’ve already discussed the increase in metabolic rates through strength training and muscle building. There are other metabolic benefits to exercise too. What was once referred to as oxygen debt and is now called EPOC (Excess Post-Exercise Oxygen Consumption) or lovingly just ‘afterburn’, is a metabolic state in which your body consumes excess oxygen and continues to burn excess calories after working out in order to adapt the body to the exercises that has just been done, while returning it to its natural resting state. The EPOC affect is greatest after exercise that involves intense anaerobic respiration, such as High Intensity Interval Training (HIIT). It is strongest, using the most oxygen and burning the most Calories immediately following the exercise. Then it slowly declines over time, lasting for a total of up to 24-48 hours after exercise.

With aerobic or cardiovascular exercise your body adapts and gets better at it. Running your first 5k is difficult and you may find you’re breathing hard to keep up, but running your second and third 5k comes easier, and you don’t find breathing nearly as difficult. While it’s true that aerobic training makes your body a more efficient fat burning engine, by definition this is not what you want. An engine that is gas efficient burns less gas to go the same distance as one that is less efficient. A body that has efficient aerobic metabolism burns fewer calories to go the same distance. With time you’ll need to run for 40 minutes to burn the same number of calories you used to burn in just 30 minutes. This is obviously not ideal if your goal is to lose weight. Aerobic training alone does not increase metabolic rates; in fact it slows them down!

If your goal is to lose fat, you’re best to incorporate both strength training and cardiovascular endurance training into your fitness regime. This is why high intensity interval training or CrossFit fitness regimes are so successful.

Aging & Metabolic Rates

As we get older all of our cellular processes gradually slow down. We build muscle at a slower pace. We store fat at a slower pace. We digest at a slower pace. Our hair and nails grow at slower paces, and we metabolize food into energy at a slower rate. Ever notice how the senior’s menu items at a restaurant have meals about the same size as the child’s menu? As we slow down on a cellular level and physically in general, our appetite reduces to match. For this reason, the time to start any health and fitness regime or good habit is right now. The stronger, healthier, fitter you are as you age, the slower your body (and mind) will break down, as you grow old. What you are today is the consequence of what you did yesterday. What you will be tomorrow is the consequence of what you do today.