On Your Mark Nutrition

Metabolic Efficiency




Teach Your Body to Burn More Fat & Remove the "Fueling" Guesswork

How many calories do I burn at different average heart rates? How much do I need to fuel for my next IronMan, 5K, etc.? Do I burn more carbs than fat? Sports nutrition guidelines suggest 0 - 60 grams of carbs per hour, but what is the specific amount I need based on my physiology?

The Metabolic Efficiency Test (MET) is a nutritional assessment that provides you with your Fuel Analysis. It can validate if your daily nutritional plan is supporting your body’s ability to burn more fat. The test identifies if you have a Metabolic Efficiency Point (MEP), the point at which your body begins to use more carbohydrate than fat as fuel.

MET is more than just trying to pin-point at which exercise intensity your body begins to use more carbohydrate than fat as fuel (MEP). It validates and offers more accurate training and nutritional strategies. The test will show how many calories you burn per minute during exercise, how many of those calories are coming from carbohydrate versus fat, and your fat-burning zone. Essentially, the test is investigating your metabolism during different intensity stages of exercise to provide you with a more custom hourly nutrition prescription.

Why Do I Need to Be Efficient at Burning Fat?

Carbohydrate and fat are used as energy, and both are burned at the same time. However, the amount of each burned (or which is the main fuel source) depends on the exercise intensity. As intensity increases, more carbohydrate is burned for energy compared to fat because carbohydrate is an easier and more efficient fuel source at higher intensities. However, we have a limited amount of carbohydrate stores (i.e., muscle and liver glycogen) in our body (~2,000 calories). This lasts for about 2 hours of moderate intensity exercise.

At lower exercise intensities, fat is more efficient to use because the energy demands are less and we have an unlimited supply in our body, including in very lean individuals. Therefore, we want to preserve our muscle glycogen for higher intensities. This requires knowing where your MEP is located and improving it by teaching your body to use more fat at higher intensities so that you can preserve your limited carbohydrate storage.

Teaching your body to rely less on carbohydrate and more on fat leads to lower needs for carbohydrate during exercise. When carbohydrate needs are reduced, then your risk for gut distress (e.g., nausea, diarrhea, gas, bloating, etc.) is also reduced.

How Can This Test Support My Weight Loss Goal?

This test will show you how many calories you burn at different exercise intensities and how many of those calories are coming from fat. This provides you with more accurate data as to how many calories you need to consume and your fat burning zone, or the precise heart rate that you burn the most fat.

What is the Test Protocol?

The test uses the most accurate and verifiable metabolic cart, ParvoMedics True One 2400. Parvo is the preferred metabolic cart of research settings, universities, hospitals and the U.S. Olympic Training Center for athletic testing (e.g., VO2 Max) and energy/nutritional assessments.

The test requires a 10-12 hour fast and can be completed on a treadmill or bike. For runners, it is a running test. For resistance-trained athletes and fitness enthusiasts, it is a walking test. For cyclists, the test is performed using your bike and the Wahoo trainer.

First, you complete the Resting Energy Expenditure test (~20 minutes). Next, you complete the exercise test (~20-45 minutes). The test starts very easy and gradually increases in intensity. For the bike test, the intensity is increased by power (watts). For the treadmill test, the intensity is increased by either incline (for walkers) or speed/pace (for runners). Your data is gathered from a heart rate monitor and by wearing a mask that samples the amount of oxygen you take in and carbon dioxide you breathe out.

Physiological measurements are recorded every few seconds, which shows us what your metabolism is doing at that particular exercise intensity (e.g., are you burning more fat than carbohydrate? How much oxygen are you consuming?). With the data, we can see your fuel mixture at different exercise intensities. Essentially, physiological testing allows for you to pinpoint efficiencies and inefficiencies.

This test is NOT like a VO2 Max test. It is meant to be a submaximal test where you do NOT exercise to exhaustion.

How Will the Data Help Me?

  • Informs your optimal fueling strategies for your daily, training and/or competition nutritional plan that are personalized to your metabolism and fitness level.

  • Provides an exercise prescription of your true fat-burning zone to help aid weight loss.

  • Provides your exercise energy expenditure - such as total calories, amount of calories coming from fat and amount of calories coming from carbs - at different exercise intensities. This means more accurate determination of your calorie burning compared to fitness trackers.

Information You receive

  • Resting Energy Expenditure: this includes resting heart rate, metabolic rate (e.g., the minimum amount of calories needed to sustain life in a 24-hour period) and how much of your calories burned at rest is coming from carbohydrate and fat.

  • Metabolic Efficiency Point: the exercise intensity at which your body begins to use more carbohydrate than fat. Some people have it and others do not.

  • Carbohydrate & Fat Calories & Grams: the amount of carbohydrate and fat calories and grams you burn at each intensity level. Intensity is measured by speed, heart rate and/or power.

  • Total Calories Burned: the amount of total calories your body burns at each intensity level. (Removes the guess work.)

  • Calorie Efficiency Ratio: an accurate range of calories to consume during exercise based on your current physiology and fitness level. (No cookie-cutter recommendations.)

  • Fat-Burning Zone: the intensity at which you burn more fat than carbohydrate. This gives you a more accurate fat-burning training zone.

  • Nutrition & Exercise Consultation: discussion of application of the data to address your specific, individual goals.

Benefits of Metabolic Efficiency Testing

  • Measures the body’s ability to enhance fat burning and carbohydrate preservation;

  • Confirms if an athlete’s nutritional program is meeting their goals;

  • Shows if you have a Metabolic Efficiency Point, and also at what exercise intensity it exists;

  • Provides physiological data that helps a dietitian personalize a nutritional plan based on your metabolism and turn it into a sustainable lifestyle based on your goals and needs.

Test Details

  • Treadmill or Bike: can be done using the treadmill (using a running protocol for runners and using a running or walking protocol for fitness enthusiasts) or bike (for cyclists). Triathletes can do both.

  • Test Duration: 30-45 minutes

  • Appointment Duration: 1.5 - 2 hours. Time is spent after the test to explain your results and plan.

  • Follow Up Testing: every ~2-3 months