What are Carbohydrates?
Carbohydrates are one of our dietary macronutrients along with protein and fat. The right types of carbohydrates are a crucial nutrient for good health but there are also less desirable carbohydrates to eat.
Basically a single sugar unit can join with other sugar units and form into many different carbohydrate structures. This structure will determine how fast the carbohydrate breaks down in the body.
When we use the term “sugar unit” don’t get confused with the sweet, white stuff we put in our coffee which we also call sugar. Scientists like to confuse us. In this instance, the term “sugar unit” refers to a building block that makes up different types of carbohydrates.
We categorise different carbohydrates as monosaccharides, disaccharides, oligosaccharides and polysaccharides.
Monosaccharides are the most simple forms that carbohydrates can break down into (mono = 1).
Two monosaccharides can join together to form a 2 sugar unit called a disaccharide (di = 2).
When between 3 and 20 sugar units join together they form a carbohydrate structure known as an oligosaccharide (olig = few). Oligosaccharides have received more interest recently as we have discovered that they resist digestion and reach our small intestines intact. We know them as PREBIOTICS and they feed our friendly gut bacteria. You will often seen them listed on probiotics supplement labels listed as FOS – fructooligosaccharides.
When more than 20 sugar units join together we call this polysaccharide (poly = many), more commonly known as a complex carbohydrate.
Basically, the more simple a carbohydrate structure is the faster it will be broken down into glucose by the body. This will create fast spikes of energy but also big surges of insulin to deal with the glucose.
The more complex a carbohydrate structure is the more slowly it is broken down into glucose by the body. This gives you a slower, steadier release of energy and avoids big surges of insulin.
Animal foods contain a small amount of carbohydrate because animals eat plants. However, our primary source of carbohydrates come from the plant world – fruit, vegetables, grains, legumes etc. If you eat more plants you will increase your intake of carbohydrates and fibre. If you eat more animal foods you will decrease your intake of carbohydrates and fibre.
No matter what the structure of the carbohydrate is when it enters the body, it will eventually be broken down to the simplest form of glucose. Glucose is the body’s primary source of energy to fuel cell activity. Some organs such as the brain can only use glucose for energy.
Correct blood glucose levels are critical and the body works constantly to maintain correct blood glucose levels. Too much glucose in the blood stream can cause damage to organs such as can be seen with people who have complications due to diabetes.
When we eat carbohydrates
- blood sugar levels rise
- pancreas releases the hormone INSULIN
- insulin moves glucose away from the bloodstream
- first it stores glucose in a form called glycogen in our muscles and liver
- if the storage space in the muscles and liver is already full and there is still excess glucose in the bloodstream insulin converts the glucose to triglycerides and stores it as fat
so even though carbohydrates are fat free, if you eat too much you will eventually store them as fat
As we use up our energy supply of glucose
- blood sugar levels fall
- pancreas releases the hormone GLUCAGON
- glucagon breaks down glycogen back into glucose for energy
- the amount of glycogen stored in your muscles has a direct effect on your energy levels – high muscle glycogen concentration gives you energy, low muscle glycogen concentration will lead to fatigue
When fully loaded with carbohydrates you have
When you run out of muscle glycogen you rely on the small reserves in the liver. When liver supplies run out you are forced to slow right down …. or even stop.
Marathon runners refer to this as HITTING THE WALL.
The insulin response is a critical process in the body to maintain correct blood glucose levels. Insulin is responsible for moving glucose away from the bloodstream. You are probably aware of the condition called diabetes where people’s insulin response does not work correctly.
Many people also suffer from a pre-diabetic condition called insulin resistance.
Diets excessively high in processed, refined and simple carbohydrates can destabilise the insulin response mechanism. In an insulin resistant state the body becomes de-sensitised to insulin and stops recognising it. More and more insulin has to be pumped out just to keep blood glucose levels normal. Eventually it is unable to control blood glucose levels no matter how much is released.
Improperly balanced diets focussing on high or low carbohydrate intake can also eventually destabilise the mechanism.
This is another reason to focus on healthy eating rather than quick-fix, fad diets.
How Much Carbohydrate Should My Diet Contain?
The general guideline is 55-60% of your total daily calories should come from carbohydrates. However, the emphasis should not only be on the amount, but the quality and type. Ideally your carbohydrates should be complex, high in fibre and come from unrefined, whole foods.
You should also eat protein and healthy fats alongside your carbohydrates as these help to slow down sugar release and balance insulin response.