What is Metabolism?

This word “metabolism” is thrown around a lot these days. You know that if yours is too slow you might gain weight. But what exactly does this all mean? Technically, “metabolism” is the word to describe all of the biochemical reactions in your body. It's how you take in nutrients and oxygen and use them to fuel everything you do.

Your body has an incredible ability to grow, heal, and generally stay alive.  And without this amazing biochemistry, what makes you a unique and individual YOU would not be possible.  It’s important because it determines our weight, our appetites, body fat levels, energy and overall physiological functioning of our bodies.  Metabolism includes how the cells in your body perform:

  • Activities you can control (physical activity etc.).

  • Activities you can't control (heartbeat, wound healing, processing of nutrients & toxins, etc.).

  • Storage of excess energy for later.

So when you put all of these processes together into your metabolism, you can imagine that these processes can work too quickly, too slowly, or just right.  This is your metabolic rate.  


What is metabolism? blog post positivelywell.com Cherise Pendleton health coaching

Metabolic rate

This is how fast your metabolism works and is measured in calories (yes, those calories!).

The calories you eat can go to one of three places:

  • Work (exercise and other activity).

  • Heat (from all those biochemical reactions).

  • Storage (extra leftover “unburned” calories stored as fat).

As you can imagine the more calories you burn at work or creating heat, the easier it is to lose weight and keep it off because there will be fewer “leftover” calories to store for later.  There are a couple of different ways to measure metabolic rate.  One is the “resting metabolic rate” (RMR) which is how much energy your body uses when you're not being physically active.  The other is the “total daily energy expenditure” (TDEE) which measures both the resting metabolic rate as well as the energy used for “work” (like exercise) throughout a 24-hour period.


What affects your metabolic rate?

The first thing you may think of is your thyroid.  This gland at the front of your throat releases hormones to tell your body to “speed up” your metabolism in addition to many other functions.  Of course, the more thyroid hormone there is, the faster things typically work, and the more calories you'll burn.

But that's not the only thing that affects your metabolic rate.  Your size, environmental inputs like toxins, the foods you eat, illness, stressors, sleep, genetics (metabolic type) and physical activity can all impact your metabolism.  We will talk about a few of these on this blog.  

Larger people generally have higher metabolic rates, but body composition makes a big difference.  As you can imagine, muscles that actively move and do work need more energy than fat does.  So the more lean muscle mass you have, the more energy your body will burn, and the higher your metabolic rate will be.  Even when you're not working out, more muscle means a higher metabolic rate.

What is metabolism? blog post positivelywell.com Cherise Pendleton health coaching

This is why weight training is often recommended as a part of a weight loss program.  Because you want muscles to be burning those calories for you.  When people lose weight their metabolic rate can slow down.  Adding more muscle mass through strength exercise can offset that because muscle creates an environment for a higher metabolism.  Aerobic exercise also temporarily increases your metabolic rate.  Your muscles are burning fuel to move so they're doing “work,” however, both types of exercise are optimal for keeping the metabolism higher.

The type of food you eat also affects your metabolic rate!  Your body actually burns calories to absorb, digest, and metabolize your food.  This is called the “thermic effect of food” (TEF).

You can use it to your advantage when you understand how your body metabolizes foods differently.  Fats, for example, increase your TEF (thermic effect of food) by 0-3%; carbs increase it by 5-10%, and protein increases it by 15-30%.  By trading some of your fat or carbs for protein (lean meat, fish, eggs, legumes, nuts and seeds), you can increase your metabolic rate.  Another bonus of protein is that your muscles need it to grow.  By working them out and feeding them what they need they will help you to lose weight and keep it off.  

What is metabolism? blog post positivelywell.com Cherise Pendleton health coaching

It’s also important to know the foods that slow metabolism and those that increase it. Processed foods like sodas, processed oils like canola, farmed meats and even conventional produce can affect metabolism.  Blood sugar, toxin levels and hormone levels are some of the reasons they can slow down metabolism.  We talked about protein-rich foods, but other foods like fiber-rich produce, certain spices and even caffeinated foods can increase metabolism. 

Other factors influence metabolism. There is plenty of research that shows the influence that things like stress and sleep have on the metabolic rate.  This is just the tip of the iceberg when it comes to metabolism and how so many different things can work to increase (or decrease) your metabolic rate.  You are unique, and while we have talked about many of the variables for metabolism, your bio-individual profile, lifestyle and environment is unique.  Making a few tweaks to your exercise and lifestyle factors can, however, have a big impact on utilizing your metabolism as part of a healthy life.

Try my recipe below for a lean (metabolism-boosting) protein.


What is metabolism? blog post positivelywell.com Cherise Pendleton health coaching recipe

Recipe (Lean Protein): Lemon Herb Roasted Chicken Breasts

Serves 4

  • 2 lemons, sliced

  • 1 tablespoon rosemary

  • 1 tablespoon thyme

  • 2 cloves garlic, thinly sliced

  • 4 chicken breasts (boneless, skinless)

  • dash salt & pepper

  • 1 tablespoon extra-virgin olive oil

  1. Preheat oven to 425F. Layer ½ of the lemon slices on the bottom of a baking dish. Sprinkle with ½ of the herbs and ½ of the sliced garlic.

  2. Place the chicken breasts on top and sprinkle salt & pepper. Place remaining lemon, herbs and garlic on top of the chicken. Drizzle with olive oil. Cover with a lid or foil.

  3. Bake for 45 minutes until chicken is cooked through. If you want the chicken to taste more “roasted,” remove the lid/foil and broil for another few minutes (watching carefully not to burn it).

  4. Serve & enjoy!

Tip: You can add a leftover sliced chicken breast to your salad for lunch the next day!






*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease