We have become a society of carb burners. That is where sports nutrition has been for the past couple of decades. Of the two main food sources the body uses for energy, carbohydrates and fats, our working muscles would prefer carbs because they create ATP (energy) faster. They are “easier” to convert into energy. As a result, we just pour in the carbs. We have fuel belts and hydro packs with pockets, water bottle holders with pouches and clothes with pockets everywhere to carry hundreds of portable carbohydrate calories. But the reality is, we are already carrying thousands of calories… in the form of our own body fat.
So, what’s wrong with carbs? I personally have been encouraging athletes to include plenty of healthy carbs (whole grains, fruits and vegetables) in their race fueling, training diets and recovery snacks for years. And nothing is wrong with carbs; we just may have lost sight of one of the most important parts of our nutritional fueling: using our own fat for energy.
What if we could use our on-board energy (our own body fat) for fuel? Most trained runners are carrying about 1,500 to 2,500 calories of carbs and 80,000-plus (!) calories of fat. Even the leanest runners. Yes, we need some carbohydrates to activate enzymes in order to burn fat for energy, and also the brain is fueled on carbs. But think of it this way: more fuel is better. One fat-burning enzyme burns a little fat; a bunch of fat-burning enzymes ignites a bonfire! So the focus of this article is how to turn your body into a fat-burning engine: Metabolic Efficiency (“ME”) training. ME training builds a stockpile of fat-burning enzymes, and voilà—the ultrarunner becomes much less reliant on consuming mass amounts of carbs during the race and has less chance of GI distress.
What Is Metabolic Efficiency Training?
Also known as fat-burning, metabolic efficiency training is not a calorie-deficient diet and it is not a low-carbohydrate, Atkins like diet. You do not need to count calories and you do not need any special foods or supplements. It is rather macronutrient partitioning—or manipulating your macronutrients (carbohydrates, fats and proteins)—and exercise adaptation—or manipulating your exercise with correct intensity training—that allows us to reap the benefits of increased fat utilization. By effectively manipulating our aerobic training, we can increase mitochondrial capacity (the number of mitochondrial enzymes). By manipulating our diet to control blood sugar and our insulin response, we will be able to fuel with fewer calories during training and racing, therefore reducing our reliance on consuming simple sugars and increasing our utilization of our on-board internal body fat. The key is that you must manipulate both diet and exercise together. If executed properly, meaningful improvements can be achieved in as little as four weeks.
Exercise Training – 30% Effect
ME training conditions your body to use fats and carbohydrates more efficiently. It manipulates cellular processes through aerobic training by increasing the size and number of mitochondria (and related enzymes) in your cells that use fat for energy. It teaches your body to use more fat by creating conditions that generate high fat metabolism. Many ultrarunners ignore or “skip over” setting up an aerobic foundation because they don’t see the immediate benefits as in speed training. This is not to say that interval training, hill repeats, etc. do not produce positive changes—they do—but they just don’t improve fat burning. You will be more metabolically efficient if you work on fat-burning (aerobic exercise) first, and then add in the other training regimes. All your runs during this period will be at a lower intensity.
Of course, you can get around this by relying on a constant source of carbohydrates coming in to fuel your muscles (aid stations, carrying lots of calories, spiking your insulin by eating simple carbs… all the time!) but you will still be carrying around some of that fat on your body. Think of it this way: you know what goes through your mind when you see a runner carrying two full bottles of water during a race that they never drink. Why carry all that weight around if they don’t use it? Hmmm. Plus, an increased carbohydrate diet can be inflammatory—not great for our long-term health.
Frequency and consistency are the keys to fat-burning training. You will need at least six to seven hours per week in this low-intensity zone for results, and it is critical to have most of your training in this zone. This means going a slower, plenty-of-available-oxygen, can-speak-full-sentences pace. Training in higher intensities also contributes to adaptations—one of which is the release of adrenaline—which leads to higher lactate formation. This has an acidic effect on free fatty acid transport that reduces fat going into the mitochondria to be used for energy. Not the adaptation we are looking for. Will you lose your speed? No, this is just a base training period; remember, we are not talking about that long—four to 10 weeks.
Implementing The Nutrition Plan – 70% Effect
The nutrition component has by far the biggest effect on your fat-burning capacity, and you must make changes to your diet to see results. The bottom line is that you remove, or drastically reduce, all grains from your diet. Not “all carbohydrates,” just grains. Your nutrition during this time will consist of lean protein, good fats and plenty of fruit and vegetables. Your sports nutrition during your runs will change too (more about that later).
Processed or refined carbs (and even whole grains) cause an insulin response or spike. As insulin increases, fat breakdown and oxidation (burning) significantly decreases and eventually turns “off” while this same insulin increase turns “up” the increase of carb oxidation. This causes the athlete to seek out more carbs and end fat burning. Controlling blood sugar through proper food selection is the key nutrition take-home message. Oxidizing more fat for energy means delaying the accumulation of lactate, which means runners will be able to maintain higher paces longer without having to take in more carbohydrates.
Remember, this is not a low-carb diet; it is a balanced diet. This means your meals will look different than the usual bagels, oatmeal and pasta. Breakfast may be black beans, spinach and eggs (or egg whites) microwaved to resemble an omelet, with some feta cheese or salsa on top. Or it may be yogurt with lots of berries and nuts added. Lunch and/or dinner may be a huge salad with steak, salmon or tofu on top. Or it may be a lean piece of meat with lots of vegetables and some fruit and a small bit of cheese for dessert. If you cannot go cold turkey on grains, then add a small bit of quinoa or brown rice to your dinner, but this will delay results somewhat. Snacks can be cut-up veggies with a yogurt-based dip. Soups, chili, stew, lettuce wraps—be creative!
What about during your workout? If we can’t use simple carbohydrates—sports drinks, gels, bars and pretty much everything we normally eat—what can we consume? Water and electrolytes. Yikes. What about “one gram of carb per minute… 240 calories an hour.”
Will I bonk? Will I die? No. You will burn and lose fat. Your fat. Why? Because you are not going at a high intensity, remember? You are not going through your carb stores; you are fat burning! The only reason you would bonk is if you are going too fast—or you run out of (your) fat. If you are running over two hours or so, you can add some non-grain based carbohydrate such as fruit, dried fruit, Lara bars, Justin’s or Pocket Fuel nut butters.
After finishing a run, you might usually hurry to make that “30-minute window” for refueling. Not necessary! You did not deplete your carb stores; you only made a dent in your fat stores. So rehydrate and have a balanced snack or meal.
Fat-burning training can help you stabilize your blood sugars, improve insulin sensitivity, lower cholesterol and LDLs, give you steady energy, lose body fat and allow you to run faster at a lower heart rate. All great results, plus putting your body into an anti-inflammatory state and able to fuel on the run with fewer calories, relying less on simple sugars. Try training first thing in the morning, fasted. Take in water and electrolytes if needed, and do not go out too fast (or too long). Remember, you want your pace to be slow enough to mobilize your own body fat for energy, and not bonk because you ran low on carbs. Daily consistency with paired nutrition and training will set a solid increased fat-burning base for big results down the line. When your speed starts to ramp up and you introduce hill repeats and speed endurance training, slowly add the carbs back into your diet, especially during races (i.e. gels) and in the recovery foods you ingest after hard sessions. That’s the time to replace the glycogen (carb) stores, not when you are primarily fat-burning in your ME training phase.