Nutrition and sport study

We will talk about an experiment where we compared two diets and performance. We have used the high fat and high carbs diets, using a maximal O2 uptake test (VO2 max). This is an indicator for cardio-pulmonary fitness and breathing at sea level  has the normal value of 61 ml/min/kg, using a maximal power of 310 watts.

On high carbs diet the time to exhaustion was 65 minutes and the glucose level in the blood after the exercise was 5.6 mmol/liter.

On high fats diet the time to exhaustion was 45 minutes and the blood glucose level after the exercise was 4.4 mmol/liter.

We know that performance is influenced by genetics (trainability and age), training (psychology, physiology and technique) and health (sickness, injury, fatigue and nutrition). Glucose as fuel has the advantage of being locally available (stored in the liver and muscle as glycogen) and has more power than the fat, but we got a limited storage (2000 kcal). Fat as fuel is a huge resource (at least 100.000 kcal), but is slow to mobilize and has less power than the carbohydrates. For high intensity exercise, glucose is ideal, for endurance exercise, fat is better. It is good to know that we can exercise for a bit over one hour is we have full glycogen stores.

Strategy for endurance exercises: we should have the glycogen stores completely filled, ingesting more carbs if the exercise is taking more than 45 minutes. You have no real benefit if you have carbs before the 45 minutes of exercise if you started fully loaded with glycogen.

Strategy for strength or power exercises: glycogen stores should be filled prior to the training or competition, you should also aim for 1.4 grams of protein per kg consumption, avoiding prolonged catabolic periods (do not fast or avoid food). If you are vegan or vegetarian, in order to achieve muscular physique, you should choose the right protein sources (beans, soy etc). Do not forget about the fluid intake during exercise, if it is cold you do not need it for very short bursts, but if it is warm and you are sweating a lot, take care of your re-hydration. Ketosis as a diet works well for medium intensity and long interval trainings (it is a high fat/low carbs diet).

Exercise benefits are important: we can lose weight if it is done long enough, but sometimes it is not apparent, as we lose fat and gain muscle, it is increasing our physical activity and functionality (especially the endurance or resistance training) and it is improving our health parameters (lowering high blood pressure, increasing the plasma HDL level, lowering the triglycerides level and improving insulin sensitivity). Talking about exercise, we need to mention supplements and ergogenic aids.

The ergogenic aids can be classified as:
-metabolic fuels (energy drinks and gels), which are good for endurance training, higher than 45 minutes;
-caffeine and caffeine related stimulants, good to exercise longer (endurance training);
-creatine monophosphate, good for high intensity training as is maintaining ATP levels up (fuel for muscle);
-anabolic substances (protein, aminoacids and other ones that will be not mentioned, as they are illegal in most countries);
-rehydrating fluids, like water, with or without electrolytes.

I mentioned ketosis earlier, i will try to explain this concept a bit more. Ketosis is defined as the formation of ketone bodies in our system. There are three ketone bodies: acetone, acetoacetate and beta-hydroxybutyrate, all of them made from fatty acids in the liver when the supply of fatty acids is highly elevated, as in the case of  prolonged fasting and uncontrolled diabetes. Normally the concentration of ketone bodies in our blood is very low, but if we try a ketogenic diet, with a high fat/low carbs content, even if some of the ketones are lost via urine, the concentration in our blood can reach 0.5 mmol or even higher if it is combined with exercise. The advantage of the ketone bodies is that even if the liver produce ketones, cannot use them, but to supply glucose to the brain during prolonged fasting, the glycogen stores are depleted after one day, and when proteins are used to convert into glucose, we experience muscle loss, this is the moment when our survival mode is activated, and the liver take the fatty acids and it will convert it into ketone bodies, delivering them to the brain as a fuel. Stored fat is used indirectly by the brain, and the need to degrade proteins is reduced.

However, the ketogenic process is dangerous during uncontrolled diabetes (diabetic keto-acidosis) or  alcohol abuse (alcoholic keto-acidosis). High levels of ketones will lower the blood Ph, being a life threatening condition. Carbs based diets leads to undetectable levels of ketones, but one day of fasting will result in 0.5-1 mmol ketosis. Prolonged fasting will increase it up to 6 mmol, and diabetic ketosis is bigger than 20 mmol.

The glycogen is prioritized to extra-hepatic tissues, the brain and the other tissues take out their share first, then the muscle is filled, followed by the liver. Both stores of glycogen to be empty is a very rare occurrence, but can happen if you do heavy training in the morning without breakfast. Our glycogen stores are mostly filled up, unless we do intense exercise or low carbs dieting or spend too much time without eating. The liver store is fully depleted after 24 hour fasting. Muscle stores are filled first in case of low carbs diet, the liver store being minimized.

How to avoid getting fat in few easy steps (part 1)

This is a story of love, a Valentine's Day special, the story of interdependence and attachment between two main macro-nutrients, let's call them carbohydrates and fats.

Carbohydrates can be simple and complex. The simple ones can be classified in monosaccharides (glucose, fructose and galactose) and disaccharides (maltose, sucrose and lactose). The complex ones are glycogen, starchi and fibers.

During digestion, the starch is broken to same degree, under the action of the amylase enzyme, secreted by salivary glands. When the carbohydrates reaches the stomach, the amylase is inactivated by the acidic medium. The digestion continues in the duodenum, under the action of the pancreatic amylase (an enzyme secreted by the pancreas). The starch is broken in maltose, sucrose and lactose. They are transformed in fructose, glucose and galactose under the action of enzymes such as maltase, sucrase and lactase).

Absorbed in the blood stream, the monosaccharides (glucose, fructose and galactose) are then processed in the liver, where almost all the fructose and galactose is used, and a big part of the glucose goes back in the blood stream, in direct relation to the blood sugar level (glucose level).

When glucose level goes up, the pancreas is secreting the insulin hormone, the role of insulin being to transform the glucose from the blood stream into glycogen, and to deposit the glycogen into the muscle and in the liver. After this process the blood sugar level is decreasing. Because of this action, the pancreas is secreting another hormone called glucagon, to break the glycogen from the liver into glucose, and when the liver deposit is finished (for example during a period of fasting), the glycogen from the muscle is used. The glycogen deposit from the muscle it is also used to generate energy when we are exercising. If we finish both of them (the deposits from muscle and from liver), the muscle is used for glycogen and we lose weight.

If both the deposits are up to 100%, the glucose is transformed into fat. But the fat is never transformed back into glucose.

Conclusions:

Fasting and exercise are helping us to deplete the glycogen deposits, so the glucose will not be transformed in fat. (Search on Google about intermittent fasting)

If we fast and exercise too much, we will lose weight (but this will be muscle weight and not fat weight).

It is possible to eat plenty of sweets, as long as you are having a fasting period right before/after, or you exercise, or both. (This is by far my favourite conclusion)


(More to come soon - this is an excerpt from the future second edition of the book The Macronutrients Pocket Guide, written by me, of course )

Take care of your glycogen deposits,
G.