Tap Into Your Fat

16/06/2014 10:12

I didn't write this. I borrowed it from Ben Greenfield, who wrote it for Lava Magazine (which has lots and lots of other fab articles in it too). I am convert and a huge supporter of his way of thinking about carbs. I do enjoy eating carbs, but mainly as wholefoods, in root vegetables, seeds etc and although I LOVE honey and pretty much all sweet fruits, I don't eat much sugar. Since I have changed my eating habits to consume more fat (only the good stuff and not much of the kind coming from animals) and less sugar, I have become much more lean, visibly so, and I am in better shape than ever before in my life... even pre-children...

So... here it is:

Metabolic efficiency for going the distance without hitting the wall.

By Ben Greenfield

Fueling yourself properly on a daily basis can train your body to be more metabolically efficient come race day, which can lead to large gains in performance.

Ninety-nine percent of Ironman triathletes walk the last half-marathon of the run.

OK, I’ll admit it. I can’t verify that statistic. But it certainly seems that way when I’m watching or competing in an Ironman. And it’s a real shame to see athletes who have poured their lives, money and precious time into an event forced to a scowling crawl when they’d much rather be running, racing and feeling at least somewhat OK.

In some cases, these athletes are walking because they’re injured, overheated or because they planned to walk a significant portion of the back half of the run. But in many cases (I suspect most cases from the discussions I’ve had with athletes), people walk because they simply hit the wall. They bonk. They run out of fuel, run out of energy and their oomph goes bye-bye.

The fact is, this shouldn’t happen, because even the leanest athlete can store tens of thousands of usable, accessible calories in the form of fat. If you learn how to tap into this bottomless well of fuel during a long day like Ironman, then you’ll not only get stronger as the race gets longer, but you’ll also have the luxury of avoiding the alternative of simply stuffing your gullet full of extra food. Your stomach has limited emptying capacity and your intestines have limited absorption rates. So if you avoid a bonk by just eating more it can be a recipe for disaster. Instead, you can limit the amount of simple sugars and calories you need to consume during your event, resulting in lower risk of gut distress, the ability to carry less fuel and the elimination of mid-race porta-john stops.


Sports nutritionist Bob Seebohar was the first endurance expert I heard use the term “metabolic efficiency,” although it’s unclear whether he actually coined the term.

Generally, metabolic efficiency can be defined as your ability to sustain more work (power, pace, etc.) while using less energy. From a physiological standpoint, this means that your body is better at using fat as fuel while sparing your limited carbohydrate stores. This gives you access to the 80,000-plus calories of stored fat you have available as energy reserves in your body while sparing your 1,500–2,000 calories of stored carbohydrates (from liver and muscle glycogen).

So now that you understand the basic idea behind metabolic efficiency, it’s time to dig down into the nitty-gritty and learn how to actually train, eat and race with this secret weapon. It isn’t as difficult as you may think and just requires a few changes in your training, eating and racing program.


Find your fat-burning zone. Your body has a certain intensity at which it will maximally use fats as a fuel. This is a direct consequence of the amount of slow-twitch muscle you’re using and the amount of oxygen you have available for your muscles to use. I’m not a fan of using equations (like 180 minus your age) to find your fat-burning zone, so here are instructions for determining your personal fat-burning zone a bit more accurately:

• Warm up on a bike for 10 minutes.

• Pedal at your maximum sustainable pace for 20 minutes. You should be breathing hard and your legs should be burning, but you should be able to maintain the same intensity for the full 20 minutes.

• Record your average heart rate during those 20 minutes.

• Subtract 20 beats from that heart rate. Add and subtract three beats from the resulting number to get a range. That is your peak fat-burning zone.

For example, let’s say your average heart rate during the 20-minute pedal session was 160. Subtract 20 and you’ve got 140. Add three and subtract three and you’re left with a ideal fat-burning zone of 137–143 beats per minute.

Compared to the results I have obtained from hundreds of athletes in a professional exercise physiology lab with all sorts of gas masks and gadgets, the results from this method are pretty accurate. But if you do want to have a laboratory test to find your personal fat-burning zone, then you should look for something called an exercise metabolic rate test, also known as a VO2 max test.

Include minimally fueled or fasted workouts in your fat-burning zone. The next step is to train your body to be metabolically efficient by including several weekly workouts in your fat-burning zone, with the important caveat that you need to do these workouts without gorging yourself on pre-workout meals or stuffing your face full of bars, gels or sports drinks.

These don’t need to be multi-hour marathon workouts. In reality, only one long, minimally fueled or fasted workout a week is all it takes to gain metabolic efficiency for the long haul. The rest of your workouts in this zone can be short. For example, I get up every morning and do about 20 minutes of calisthenics, yoga or walking in my maximum fat-burning zone—after having not eaten for about 12 hours. And then for my weekend long swim, long bike or long run—just one of the three each week—I avoid eating, drink water only, or occasionally use very low-calorie sources of fuel, such as amino acids, caffeine and electrolytes (three compounds that can make fasted or minimally fueled metabolic efficiency workouts far more pleasant).

Don’t neglect intervals. One big mistake athletes make upon finding their aerobic, metabolically efficient fat-burning zone is to simply do all training in that magical window. But you also need to include interval training. Your body has a special mechanism called the “Cori cycle” that allows your body to shuttle lactic acid to the liver, where it can be converted into usable energy in the form of glucose and used by your muscles.

By implementing intense interval training, isometric body weight holds and weight training in your program, all of which build up lactic acid in your muscles, you actually train your body to make its own glucose, which comes in handy as an extra fuel source to rely upon during the more difficult stages of your race (e.g., passing another cyclist in the 60 second nondrafting window or summiting a tough climb). You don’t need to do these harder workouts in a fasted state (which can be stressful on your nervous system). I’m a fan of doing the harder workouts two to three hours after a meal, or after a quick morning snack like a piece of raw fruit.


Now that you’ve found your fat burning zone and are implementing minimally fueled workouts, it’s time to fuel your body to maximize metabolic efficiency. Here’s how.

Eat more fat and less sugar. You can train your body to use fat as a fuel via the process of beta-oxidation by eating more fat and less carbohydrates. Realizing that many triathletes tend to have type A, all-or-nothing personalities, I should emphasize that I do not endorse zero-carbohydrate diets, and for many people I also don’t endorse a ketogenic or high-fat diet. But I do recommend limiting sugars and eating a diet that is as high as 40–60 percent healthy fats (I personally eat an 80 percent fat diet). It’s important to realize that proteins are very easily converted into sugar, and the nitrogenous buildup from excess protein intake can be hard on your kidneys, so if you limit carbohydrates, replace them with healthy fats, not excess protein. It’s simple to start. Replace toast and fruit in the morning with eggs and avocado. Replace a grain wrap and light yogurt at lunch with a nori seaweed wrap and full-fat yogurt. Or replace pasta at dinner with an extra helping of vegetables and olive oil.

Limit snacking. You only need to eat three square meals a day. Yes, even if you are a hard-charging Ironman, three nutrient-dense, high-fat meals can easily fuel a day of workouts. There is no evidence that eating more often than that will do anything significant for your performance from a metabolic standpoint. I’ll occasionally throw in a high-fat snack such as coconut milk and almond butter as a fourth meal or snack. The only exception to this rule is days when you have double workouts within eight hours of one another. In this case, a quick snack immediately after the first workout (if a real meal isn’t an option) can improve the quality of that second workout.

Use supplements. Supplements can make the transition to metabolic efficiency much more pleasant. The items that will serve you best as you make the transition are the following:

• D-ribose—This is a “negative glycemic index” sugar that helps to rapidly replenish your ATP stores, even without high carbohydrate intake or other simple sugars that take you out of your metabolic efficiency window. I use X2Performance as my main source of d-ribose.

• Amino acids—During hard workouts and races, a branched-chain amino acid or essential amino acids supplement can supply your body with a sugar alternative in the form of a fast source of fuel that also keeps you from cannibalizing muscle. I use Master Amino Acid Pattern (MAP) and Vespa amino acid mixture (VAAM) for this.


Eating a pre-race breakfast high in fat can help keep your body in a state of fat-burning efficiency during an Ironman.

• Caffeine—It can increase you body’s ability to tap into fatty acids. In addition to the “coffee for breakfast” approach described below, many popular supplements and sports drinks contain varying amounts of caffeine to suit your tolerance.

• Digestive enzymes—If you’re not used to eating a high-fat diet, you may not have adequate levels of lipase in your gut. This enzyme is responsible for digesting fats. I recommend using digestive enzymes for four to eight weeks when you first begin eating more fat.

• Electrolytes—When your body sheds carbohydrate during the transition to metabolic efficiency, it also sheds water and electrolytes, which can lower blood pressure and make you feel dizzy and uncomfortable. So it’s not only important to stay adequately hydrated, but also to consume a higher than normal amount of sodium, potassium and other electrolytes. I personally consume three to four grams of Himalayan or Aztec sea salt every day.


Now that race morning has rolled around, there are just a few additional tweaks you need to make.

Eat a high-fat breakfast. You can eat a high-fat breakfast every day, but on Ironman race morning, I’ve found a particularly potent combo to be a style of coffee that is growing in popularity among athletes. It’s called “bulletproof coffee” and consists of 8–16 ounces of black coffee blended with 1–2 tablespoons of coconut oil or a more concentrated form of coconut oil called MCT (medium chain triglyceride) oil, 1–2 tablespoons of grass-fed butter, 1–2 tablespoons of a hydrolyzed collagen or amino acid source, and optionally, for extra calories, 4–6 ounces of full-fat coconut milk. You can add cinnamon, vanilla or stevia to taste, and when you slam this combo about two hours before an Ironman, you’ll be full of clean-burning fuel that gives you a real buzz at the starting line and keeps your body in a state of fat-burning efficiency.

Use a combination of easy-to-digest fats, easy-to-digest proteins and slow-release starches. Most popular sports drinks, chews and gels contain a mix of simple sugars, such as fructose and maltodextrin. While you can perform just fine using these sources, they can shift your body towards sugar use and away from a maximum fat-burning state. However, if you only eat fat during the race, you’re going to find yourself with some serious GI distress, since the body has limited fat absorption and digestion capabilities. Instead, you can consume 100–200 calories per hour of easy-to-digest fat sources such as coconut oil or MCT oil. This can be combined with 10–20 grams of amino acids from powders or capsules, along with another 100–200 calories per hour of a slow-release source of starch (I prefer a supplement called UCAN Superstarch for this approach). All of these can be mixed together into a water bottle or flask and dissolve much better when mixed in a blender before the race.

Top off your tank when appropriate. In a long race like an Ironman, you’re going to find that using the fuel sources described above can leave you still feeling depleted once you’re a few hours into the run, especially if you’re the type of athlete who likes to give a final kick, which uses carbohydrate at a very fast rate. For this reason, adding a complex form of carbohydrate during the last hour or two of the bike can give you that extra kick you need later on the run. For example, simply consuming an extra 200–300 calories per hour on the bike (from a source such as an energy bar) can ensure that your fast-burning fuel tank isn’t empty when you get to the run.

As you can see, there are some definite tweaks to be made if you want to use the strategy of metabolic efficiency, but once you put all the pieces together, you’ll find that you’re able to feel stronger as the day gets longer, consume less unhealthy simple sugar sources and teach your body to rely upon its own fat stores as energy. LAVA

Ben Greenfield is author of the book The Low Carbohydrate Diet for Triathletes at Lowcarbtriathlete.com, and has also written a book about how endurance athletes can achieve the ultimate combination of health and performance at Beyondtrainingbook.com. He recently raced Ironman Canada (9:39) and Ironman Hawaii (9:59) using the exact training and fueling approach you read about in this article.