Carbohydrate loading is a concept of eating excess carbohydrates to fuel endurance activity. It has long been promoted as essential to ward off fatigue and ‘bonking,” a sports term to mean depleting ones fuel sources and flooding with lactic acid. In my day in nutritional sciences, one would get a failing grade if countering the ‘carbohydrate and fuel’ theme. Yet at international marathons the only athletes eating pasta and pizza were the amateurs. We elite ranked athletes ate normal portions of fish or steak, vegetables, salad, and small serving of rice if any starch at all. So how do elite athletes excel without loading their muscles with pasta, bread and potato?
Endurance Training Without Carbohydrates – Key Concepts:
- Eliminate Carbohydrate Dependency
- Rein in the insulin flush / Control performance by controlling insulin
- Keto-Adaptation: Burning Fat as Fuel
Eliminate Carbohydrate Dependency
Simply put, eating carbohydrates creates a dependency on carbohydrates. Fueling with carbohydrates creates a dependency for carbohydrates and inhibits fat mobilization. Carbohydrates are only an essential fuel for sports performance as long as you eat them. Stop eating a carb-centric diet and your body stops needing carbohydrates for fuel, even for endurance sports performance.
Your body has the capacity to store approximately 2000 calories of carbohydrate fuel as glycogen divided between your liver and lean muscle mass. Yet the average active person with average lean muscle mass would have 40,000 calories of fat storage as potential fuel. If it is your habit now to eat starch regularly your muscles and liver would store it as glycogen. Once these stores are full, excess carbohydrate calories will convert to triglycerides and store as fat. During exercise when you start to near the end of your muscle and liver supply of glycogen the pH drops to create a more acidic blood, lactic acid starts to accumulate because of the increase of Co2 and you slow down to shunt needed glucose to the brain. This is bonking, it is laborious and hurts and turns many endurance athletes off of the love of training. To counter the drop in available glycogen to glucose endurance athletes have been coached to supplement with gel pack, brown banana, or a sports drink. And miraculously these glucose rich treats do the trick, for a little while. Endurance participants find themselves in a vicious cycle of slurping drinks and sucking on gel packs (which require loads of water per tablespoon), every 10-20 minutes to delay fatigue. So carbohydrate as the dominant fuel is NOT increasing endurance rather it only delays fatigue. What if your body processed fatty acids as the preferred fuel?
Insulin Controls Performance:
Carbohydrates in any amount require the hormone Insulin to enter into cells to be used as fuel. Insulin is king, when it is secreted other hormones are suppressed. Regular ingestion of starchy foods throughout the day, even ‘healthy’ grains and unrefined starch like yams or rice, requires a steady squirt of insulin into the blood stream. Insulin then out-competes other hormones that would be used to mobilize fat. In order to up-regulate fat mobilizing enzymes carbohydrates have to systemically be decreased. The body has to be trained to mobilize fat for fuel. A regular diet of starch and glucose supplements delays access to fat stores. This delay will force a physical slow-down and lactic acid will start to flood into muscle cells. All the while precious glucose molecules will be used for the brain and nervous system and 40,000 calories of fat sit locked up inside their fat cells because insulin’s presence won’t let them out. Insulin is a bit of bully. It can suppress fat breakdown that lasts for days after the consumption not just a few hours. To optimize endurance capacity and performance rein in the insulin flush and train metabolism to access fat without delay.
Adapt a Fat-Burning Metabolism:
To readily access stored body fat for fuel the metabolism has to be conditioned to do so. It will take two weeks to a full month of carbohydrate restriction to allow your body to adapt to fat burning preference. Keto-Adaptation is the rapid mobilization of fat, ‘rapid’ because the body can be trained to use fat as the preferred fuel at rest or during exercise and by-pass any available glucose. That’s right you can burn fat and NOT rely on carbohydrates at all. Fat converts to ketones in the liver. Ketones are used by the brain as fuel if and when glucose gets low. This is NOT ketoacidosis, which affects uncontrolled diabetics. Ketones are always present in our blood in relatively low levels. As your carbohydrate intake fluctuates ketones rise and fall accordingly. Ketones are made from fatty acids in the liver and because they are smaller than fatty acids they are water-soluble. The lower your carbohydrate intake goes the lower insulin goes and the more fatty acids you burn for fuel. Hormone sensitive lipase, (HSL) separates fatty acids from their glycerol backbone and it is stimulated by endorphins, growth hormone and thyroid hormones. So your exercise will increase HSL.
In the first two weeks of gradual carbohydrate claw-back ketones in the blood will rise. Exercising muscles will use ketones and fatty acids for fuel and the brain will use the ketones. The second two weeks of carbohydrate restriction your muscles start to use fatty acids directly for fuel and the ketones are reserved for brain function. This is the point where your muscles start to depend on fatty acids directly for fuel and give up altogether on glucose for the ATP generation.
To train your endurance efforts to use fat for fuel strictly follow these steps.
- Accelerate ketosis with an exercise bout that burns close to1800 calorie. This will vary depending on your current fitness level. It would be in the area of a 2-4hour endurance effort of running, cycling, hiking. Supplement only with electrolytes without sugar, (E-Load is a good product), and coconut oil in clear tea.
- Claw-back carbohydrate intake either gradually over a two week period or if you have done this before all at once. The 50 grams of carbohydrate per day ceiling will push most people into the ketone level that dependably fuels the brain and avoids carbohydrate binging. If done too quickly the body will make glucose from protein. (gluconeogenesis)
- Ensure potassium and sodium intake is sufficient from homemade broth intake and lots of steamed vegetables.
- Protein intake should be about 1.5 grams per kg of weight
- Fat intake will increase to about 65% of total calories. Avoid altogether soybean oil, safflower, corn, cottonseed, peanut, mayonnaise made with these oils, and limit canola oil. The best fats for keto-adaptation are coconut, palm, lard, butter, ghee, and high concentrate Omega 3’s flaxseed and pumpkin seed oil.
- A magnesium/calcium/ potassium supplement taken daily
- Use organic sea salt, kelp liberally. A salty broth will help keep sodium at 1-2 grams per day as the kidneys tend to flush sodium more regularly with low-carb diet.
Keto-adaptation is not for the faint of heart. But if you are brave enough to break through the carb-dependent fuel barrier you won’t be disappointed. Fueling on fat for endurance feels effortless and fluid. It pushes back the lactic acid accumulation and allows for more efficient oxygen utilization. Our next blog will review the mechanisms of electrolyte balance in keto-adaptation more thoroughly. In the meantime perhaps start to pay attention to your carbohydrate habit and toy will eliminating one carb-dense food every few days. Remember to supplement that calorie void with quality fat from nuts, avocado and raw cheese. Take your time it is well worth the effort.