Carbohydrates are the bodies preferred source of energy, as it is the first food type which is burned for energy in the body. Barring the exception of milk all carbohydrates come from plants.
Nutritionists differentiate carbohydrates into two subcategories, simple carbs and complex carbs. Simple carbs are easily digestible sugars such as monosaccharide and disaccharide, complex carbs are starches and fibre, both of these are known as polysaccharides.
The division is created to differentiate the speed of which they are processed by the body, simple carbs are quickly absorbed by the body, complex carbs take a lot longer for the body to digest as they need to be broken down further.
What happens to carbohydrates in our body
Both simple carbs and complex carbs are broken down into simple sugar in the form of glucose to be used by the body, when glucose is taken or produced by the body it enters the bloodstream and causes the pancreas to produce insulin which is required to feed glucose into the muscles and force excess into the liver. The job of insulin is to regulate the amount of glucose in the bloodstream, if there is too much glucose in the blood it can result in blindness, if there is a lack of glucose in the blood it can lead to hypoglycaemia which begins by causing the person to feel faint and pass out.
Simple carbs are processed far quick by the body and converted into glucose far quicker, this can cause blood sugar spikes and the pancreas needs to quickly produced high amounts of insulin quickly to push the glucose into the muscles and any remaining into the liver, if there’s any glucose still left after filling the liver then the surplus is converted to fat in the liver to make room by a process called de novo lipognesis (DNL), fat can be stored long term by the body in the adipose tissue which is predominantly in the butt, thighs, waist and back. The distribution of adipose tissue differs between men and women greatly and slightly differently between different people of the same sex.
The blood sugar spike can be limited greatly by eradicating all simple sugars from your diet. Because complex carbs take longer for the body to digest, the glucose is released slower over a longer period of time which allows the body to cope a lot better. The end effect is that glucose dripped into the bloodstream in a more manageable way, so there is less surplus which means less glucose is converted to fat and stored in your adipose tissue.
Insulin response in relation to exercise.
We’ve established that insulin is required to delivery glucose into the muscles, this is particularly important after working out. Usually during a workout the muscles will start to deplete their energy reserves, and after workout need to be replenished, this is the perfect time to take high sugar carbohydrate drinks as it creates an insulin response to allow the muscles to be fed. In addition to this insulin is require for protein synthesis. So it’s an important factor when working out.
Now for the sake of simplicity it is commonly taught that simple carbs converts to glucose a lot quicker, and a lot slower for complex carbs. While this is generally true, there are many that do not fit the norm. So it’s important to study different carbohydrates on a case by case basis. Potatoes for instance can cause a rapid insulin response, far quicker than sucrose.
You can look at the speed in which carbohydrates convert to sugar in the Glycemic Index (GI) table below. The greater the number, the quicker it can convert to glucose by the body and cause the insulin spike
Some of the common carbohydrates with the associated GI score are listed below, the GI rating of a carbohydrate is simple the rate at which it converts into glucose by the body, glucose is the raw energy source and is rated 100. The test is done by feeding test subjects with a given carb and testing to see how much glucose is present in the blood stream subsequently afterwards.
|Lettuce||10||Sweet potato||44||Figs, dried||61|
|Fructose||19||Bran Buds||47||Pineapple, fresh||66|
|Pear, fresh||38||Fruit Cocktail||55||Bran Flakes||74|
|All Bran with Fiber||38||Oat Bran||55||Shredded Wheat||75|
|Strawberries||40||Apricots, fresh||57||Baked potato||85|
|Orange, Navel||42||Kiwi||58||Corn Flakes||92|
|Peach, fresh||42||Bran Chex||58||Glucose||100|
|Pear, canned||43||Rice vermicelli||58||Dates||103|
As you can see complex carbs tend to have a lower GI rating than simple carbs, barring the exception of a few anomalies, fructose has a deceptively low GI rating due to the way it is processed, unlike all other carbs which are processed during digestion, fructose is sent straight to the liver to be converted into glucose, which tends to take longer than digestion. The liver turns much of fructose into fat rather than sending it into the bloodstream as glucose first, therefore fructose should be avoided at all costs.
Why is fructose treated differently than other carbs?
Glycogen is the secondary energy source in the body and can be produced by the liver and the muscles. In addition to this liver actually uses glycogen as an energy source by itself. Glycogen can be produced by converting it from glucose, however it is four times easier for the liver to create glycogen from fructose than glucose. This is why fructose is sent directly to the liver, if the liver’s glycogen stores are low it will replenish its stores from fructose, if not then it will be converted to fat, hardly any will be fed to the muscles.
Because of this fructose is probably the worst carbohydrate you can consume, because the overwhelming majority of fructose get turned straight into fat. It is commonly found in soft drinks and fruit juices that use high fructose corn syrup as the main sweetener. It is also found in table sugar (sucrose) which is part glucose part fructose.
Carbs sound awful, why do we bother with them?
Carbohydrates are fine in moderation as long as you avoid fructose in your diet and try to stick away from the high GI carbs as much as possible [glucose based simple carbs are fine post workout].
If you’re on a fat loss diet you should only consume carbohydrates lower than GI score of 55. Also limit your carbohydrates to the start of your day.
Fibre in carbohydrates
Fibre isn’t an energy source unlike Protein, carbohydrate or fat, and therefore is under looked by many people, but make no mistake it is absolutely crucial for your well being. Fibre is usually derived from the outer layer of fruits and vegetables, although most fibres aren’t digestible by the human body, our bodies still need any fibre it can get. Fibre has numerous role in your health
- The help with transit times of your bowel movements, it provides the lubrication needed to excrete waste and prevent constipation.
- Helps keep your intestines clean and helps prevent potential problems such as haemorrhoids and colon cancer
- When consumed with high GI foods, fibre helps reduce the release of glucose into the bloodstream.
Fibre is essential for the routine digestive functions of the body, a good source of fibre are all-bran cereals, wholemeal pasta, baked beans, avocado, sweet potato.