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Make Your Body More Metabolically Efficient

By Bob Seebohar | Jan. 24, 2012, 12 a.m. (ET)

Now is the time of the year when the thoughts of dropping weight and body fat become extremely popular among triathletes. But what about planning your race day nutrition and eliminating the GI distress monster that rears its ugly head during your races? The concept of metabolic efficiency can have a significant impact on body composition and GI distress and can reduce your need for simple sugars during a race.

Efficiency is a term that is typically associated with sport. From a nutrition perspective, being metabolically efficient simply means being able to use the proper nutrients that are stored in the body at the right times.

Metabolic Efficiency Training (MET) offers specific nutrition and physical training alterations that will manipulate cellular processes in order to improve the body’s ability to utilize macronutrients. The main benefit of MET is that it allows the body to more efficiently use macronutrients.

Aerobic training induces cellular changes that improve the body’s efficiency in using macronutrients, specifically fats. Mitochondria, which produce ATP, increase in size and number as a result of aerobic training. Mitochondrial enzymatic activity also increases. More specifically, those associated with the Kreb’s Cycle and respiratory chain, the shuttle system that transfers protons developed through glycolysis into the mitochondria for use in the respiratory chain and fatty acid metabolism. This is important because it allows the body to use more available fats for energy to fuel exercise.

The oxidation of fat by the mitochondria is the main source of energy when exercise intensity is low. Because glycogen stores can deplete rather quickly (after about 2-3 hours of moderately intense training) and supplemental carbohydrates cannot provide adequate energy for longer distance training due to GI distress or the inconvenience of transport, it is beneficial to teach the body to become more metabolically efficient in using fats as an energy source. These metabolic changes can typically happen in as little as two weeks with the proper eating and training program.

The Crossover Concept
The crossover concept is a physiological term that describes the relationship of fat and carbohydrate oxidation to intensity of exercise. As exercise intensity increases, the body prefers to use carbohydrate for energy. The crossover point is the intensity where fat and carbohydrate intersect with the energy from fat decreasing and the energy from carbohydrate increasing. The crossover point, or what I term “metabolic efficiency point,” can be manipulated with proper aerobic training but only if intensity is maintained at lower levels. Training at higher intensities will surely improve power and speed but it will not induce macronutrient partitioning that improves fatty acid metabolism during training. A triathlete who is more aerobically conditioned can use more fat as energy at higher intensities and this can provide a glycogen sparing effect.

The metabolic efficiency point can be further manipulated through nutrition. Eating a higher carbohydrate diet will lead to an increase in carbohydrate oxidation. While the benefits of eating a higher carbohydrate diet are certainly justified during certain times of the year when training load is high, this type of eating can work to a triathlete’s disadvantage during lower volume and intensity cycles.

Eating and therefore oxidizing more carbohydrates decreases the body’s ability to oxidize fat at higher intensities; therefore, to properly teach the body to utilize fats more efficiently, carbohydrate intake should be more balanced with lean protein and healthy fats. This is not a recommendation to follow a low carbohydrate diet. The goal is to balance macronutrient intake so proper metabolic changes can be implemented.

The good news is that any athlete can accomplish these metabolic changes in a short amount of time. There are no special tools or devices that you need.  The following three steps will help in your quest to become more metabolically efficient and use more of your fat stores as energy.

1.   Adopt a nutritional paradigm shift. As you approach your daily food selection, prioritize your meals and snacks. First on your plate should be a source of lean protein and healthy, omega-3 rich fat. Second up is a healthy portion of fruits and/or vegetables. Then, save just a little room for those whole grains and healthier starches if you decide you need them at this point in your training cycle.
2.   Use the “out of side, out of mind” concept. Nutrition supplements that are high in simple sugars will inhibit your progress of reaching metabolic efficiency.  Focus on eating good meals as I described above and save the nutrition supplements for when you really need them. Remember, you are trying to teach your body to use its fat stores more efficiently.
3.   Follow the 90/10 rule. Stay on track with these steps 90 percent of the time and allow yourself to “miss” the other 10 percent of the time. Remember, you are human and life happens. Don’t stress out if you have the occasional “miss.” Be honest to yourself and allow some room to deviate. 
This is the best time of the year to implement a metabolic efficiency plan. Focus on good aerobic training with some nutritional shifts and you will be on the road to using more of your internal fat stores as energy.

For more information about this topic, refer to Bob’s published book “Metabolic Efficiency Training: Teaching the Body to Use More Fat” at

Bob Seebohar, MS, RD, CSSD, CSCS is a Sport Dietitian, USAT Level III Elite Coach, USAT Youth and Junior Coach and an exercise physiologist. Bob was previously a sport dietitian for the U.S. Olympic Committee and the 2008 Olympic triathlon team and has worked with hundreds of age-group triathletes and professionals to help them lose weight and body fat while optimizing performance through nutrition periodization and metabolic efficiency. Bob recently published a Metabolic Efficiency Recipe book with over 100 recipes that provides athletes even more options to follow metabolic efficiency training. Visit for more information.

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.