As a runner it is important to understand nutrients otherwise you can never develop an appropriate diet to fulfill your demands. A sufficient diet is the first and perhaps most important step in preventing injuries.
To begin with we need to understand that there are 3 macro (large) groups of nutrients. There are carbohydrates, fats and proteins. Everything in your body is a combination of those three macro nutrients, so yes you are what you eat,,, but not really! Because when you eat foods you break them down into micro (very small) nutrients before ingesting them into your body. Once these micro nutrients are ingested our liver and some special cells around the body can build the products they need using these micro nutrients.
Carbohydrates get broken down into simple sugars most notably glucose. Fats get broken down into fatty acids and proteins are broken down into amino acids. This seems like a lot of hard work breaking foods into micro nutrients only to build them back up. However it is essential because our bodies recognise all our proteins (as self proteins) so we don’t attack them with immune cells (antibodies). If we ingest another animals proteins (these would not be self - foreign proteins) we would have an immune response every time we had a meal. “Not Good”. So we break protein into amino acids and rebuild those back into (self) proteins in the liver!
The presence of a foreign is why we get sick (Fever, Pain, Inflammation, Nausea) when we have a bacterial (small organism secreting protein) or Viral (small piece of RNA or DNA with a protein coat) infection. These proteins are foreign and our bodies go to war with them which makes us feel weak and tired.
If we look at the calorific value of these macro nutrients we see that:
Carbohydrates yield 4 cals/gram
Proteins yield 4 cals/gram
Fats 9 cals/gram
A calorie is a unit of energy so measuring calories I believe is a totally arbitrary way to try and lose weight because the end result of each macro nutrient is different therefore the calorie count gets very difficult to monitor. Let me explain!
A calorie (in food terms) is the amount of energy it takes to increase a kilogram of water by 1 degree Celsius. So to discover the amount of calories in any food all you need to do is put it in a glass box under a kilo of water, set it on fire and measure the increase in water temperature when all the food is burned and work out the amount,,, or read the label!
Our bodies are programmed to store fat whenever possible, this is a unique mammillary trait to have as much stored energy in case of times of famine, since we now know fats yield the most amount of energy (9 cals/gram) they are the best to store. But what happens if you store too much and there is never a famine??? You get fat!
This programming also means that whenever carbohydrate is available, it will be burnt before the fats. This is achieved by the release of insulin from the pancreas (insulin tells every cell in you body to burn glucose instead of fat). Our bodies do this because fats are not water soluble and carbohydrates are, therefore you would need to carry a lot of water around if you were to store carbs like the way you do fats and with a low yield of energy (4 cals/gram) it just isn’t worth the time.
Carbohydrates are the easiest to burn up for energy (think of newspaper) but don’t last long, fats are more difficult to burn up (think of wood) and last a long time. Proteins are rarely used for fuel and are more difficult to burn than carbs (think of cardboard) with a relatively low yield of energy too.
The first indication that you are burning proteins as a source of fuel is the smell of amonia from your training clothes after you have finished a run or cycle. You may also develop sores at the side of your mouth or mouth ulcers. There are many more signs but these are the most noticeable. You might want to ensure you are eating the correct amount of carbohydrate and fats to minimise this. Proteins are the building blocks of the body and its never a good idea to smash up the blocks in the walls of a building.
Proteins are not stored in the body so whatever is not used is excreted therefore it’s pointless counting those calories!
The next time I will explain how you go about ensuring that you are in fact burning the fats when you are running! Isn't that what we all want to do?