I often get this question when I tell people that I offer metabolic testing from an FDA approved device called the BodyGem®.

In this post I will explain

  • What is metabolism (in a nutshell)
  • Why should you care about my metabolism
  • Why should you have my metabolism tested

Woman getting metabolic testing

For the sake of simplicity

Metabolism is the rate at which your body burns calories. Technically it’s the chemical process which occurs in your cells to create and break down energy. It’s a really complicated chemical process which could take years to fully understand. But it’s the rate at which you are burning calories (using energy).

Metabolism is broken down into 5 parts:

RMR (resting metabolic rate) :  Energy used to do basic bodily functions and have your organs work. It’s your metabolism when you wake up in the AM (hence resting) before any you do any activities such as eat.  It’s usually about 75% of your total metabolism.

TEF (Thermic Effect of Food) : Energy used to digest and use the food you eat. Our body uses energy to break down food. Protein is the most thermogenic macronutrient which means it takes more energy to digest protein than fat or carbohydrates.

NEAT (Non Exercise Activity Thermogenesis): Energy expended for everything we do that is not sleeping, eating or  exercise. This includes walking to work, cleaning the house, shopping, fidgeting,  playing with your kids, showering, etc.

TDEE  (Total Daily Energy Expenditure): The sum of your RMR+TEF+NEAT which determines your daily caloric expenditure. If you consume the same calories as your TDEE you will not gain or lose weight. If you consume less you will lose weight and more you will gain weight.

EAT (Exercise Activity Thermogenesis): The calories you use while exercising.

There are a few formulas that have been created by scientists over the years which we use today to determine your RMR . They combine your age, height, weight and sometimes body fat mass to determine your RMR.  The most commonly used are the Harris Benedict Equation, The Cunningham Formula, The Mifflin St. Jeor Equation, and The Nelson Equation.  Some people prefer to use one over the other, it’s a personal preference but at the end of the day they are formulas not YOUR EXACT metabolism which means there is room for error. Often times with people who are active and have muscle, the formulas can be off upwards of 400-500 calories. It can be off for regular people as well. But lean body mass does play a factor in your metabolism.  These formulas have been used for years for an estimated metabolism, sometimes they are very close sometimes they vary 50-100 calories but the only way to find out your actual Resting Metabolic Rate is to use a direct or indirect calorimeter.

Once you know your actual RMR you can then add in your activity level and figure out your TDEE. When we have your TDEE we can then determine how many calories you should eat daily to reach your body composition and performance goals.

Why should you care about your metabolism & why should I get it tested?

Knowing your exact metabolism allow you to eat proper calories for your goals. If your actual metabolism is 400 calories higher than a formula prediction that is almost an entire other meal you could and should be eating every day. It could help with your energy levels and workouts as well as building muscle and overall quality of life. The more calories we eat the higher we can keep our metabolism, the less we eat the more our body will adapt and the slower it can make our metabolism as well as the calories /minute of our exercise. This is called Adaptive Thermogenesis.  Which means ideally we want to eat as much food as we can while still maintaining or hitting our goals.

As we age our metabolism declines which is why it is important to keep it as high as possible for as long as possible. Building lean body mass, daily exercise, NEAT, as well as eating the proper amount each day will help keep your metabolism healthy!

Overall knowing your true RMR is an important tool for weight loss, muscle gain and optimal performance.

Calories per day diagram

How does the BodyGem® work? 

The BodyGem measures your oxygen consumption (Vo2) to determine your RMR. The hand- held device is placed into your mouth while a nose clip is on your nose to prevent air from escaping. You simple breath into the machine as you normally would breath for about 5-10 minutes until the machine registers a number for your metabolism.

When clients do a metabolism test with me I give them their RMR,TDEE and recommended daily calorie intake to reach their goals. If clients are interested I also offer a 1 hour nutritional consultation which reviews their current nutrition, fitness and lifestyle habits. We discuss your goals and map out a plan of action to reach your goals based on your metabolic reading. We also go over any questions clients may have regarding nutrition from supplements, gut health, vitamins & minerals, eating frequency, diet trends, etc.

You can not exercise, eat or take any stimulants including caffeine and medication 4 hours prior to testing. This allows the machine to measure an actual resting metabolic rate. If you are in NYC or ATL and interested in having your metabolism tested please contact me at Jaclyn@athleatsnutrition.com