Part 1: Carbohydrates
Nowadays we are bombarded with health messages left right and centre, and it seems like a monstrous task to stay on top of what is actually healthy. What makes things even harder is when messages conflict with each other. Dark chocolate was good one moment, and then all of a sudden, it’s bad. Alcohol had important benefits, and then those get debunked and the advice is to avoid it at all costs.
A comedian’s take on this encapsulates it well – link to the vid below. Just pardon the rough language 😛
As the title suggests, this blog will be about nutrition. But as the Social EXERCISE Project, why are you writing about nutrition?
Health is a complex interplay of a variety of factors. Exercise physiologists are health professionals providing lifestyle interventions. Diet and exercise are big components of a person’s lifestyle. It is incredibly important to have a good foundation in nutrition for your health, because a person will eat more often than they will exercise. As an exercise physiologist, we are not experts in nutrition and dietetics, but it doesn’t take a dietitian to tell you that you need to drink less sugary drinks. We will get into exercise related content once the foundation of nutrition has been set.
For this blog, we will go through the science behind nutrition. But if you need individualised and tailored nutritional and diet plans, you need to go consult a dietitian or nutritionist. Please do not try to make drastic changes without professional consultations.
So here we go.
If you’ve been reading health related articles, you will have come across the term macronutrients. These refer to carbohydrates, fats and proteins, they work to maintain our bodily functions during rest and in physical activity.
Let’s go through one of the macronutrients.
Carbohydrates
We know that the world is comprised of different atomic molecules. When carbon (C), hydrogen (H) and oxygen (O) combine in a ratio of 1:2:1 respectively, they will form a carbohydrate.
Monosaccharides are a term to describe the most basic unit model of carbohydrate. Maybe you are familiar with some of them: glucose, fructose and galactose. Glucose (C6H12O6) is one of the monosaccharides that gets the most attention because of its functions in the body. It serves 3 different functions after it gets absorbed into our body:
- To become an energy source of cellular metabolism
- To become glycogen when stored in liver and muscle
- To become fat (triglycerol) for later use when energy is needed.
Fructose is a form of sugar found in fruits and honey, and it gets digested a lot quicker, and galactose combines with glucose to become the milk sugar in the mammary glands for species that breastfeed. The body may also convert it to glucose to serve the functions mentioned above.
Oligosaccharides are carbohydrates when 2-10 monosaccharides bond together – known as simple sugars. Some you may have heard of again: sucrose, lactose and maltose.
Sucrose (glucose + fructose) is the common sugar we see in cane sugar or brown sugar.
Lactose (glucose + galactose) is the sugar found in milk.
Maltose (glucose + glucose) is the sugar found in beer, cereals and germinating seeds.
Polysaccharides are sugars that have a linkage of anywhere from 3-1000+ sugar molecules. These are the sugars found in plants and animals that we eat.
From plants, we derive starch and fibre.
Starch is a stored version of carbohydrates in plants – in cereals, pastas, bread etc. It has 2 forms: amylose (chains of glucose molecules) and amylopectin (a lot of monosaccharides branched together). Starches with more amylopectin will digest and absorb a lot quicker, where the reverse is true for those with more amylose.
Fibre is a polysaccharide that resists chemical breakdown by our digestive enzymes. It is found exclusively in plants – the leaves, fruit skins, seeds etc.
Fibre is a really important component to a diet anecdotally as it helps us to have regular and smooth bowel movements. There’s a plethora of research around fibre and its benefits against a lot of cardiometabolic disease. Something to consult a dietitian or nutritionist about as it is worth investigating further.
Glycogen is the animal version of starch. It is the storage form of carbohydrate in animals. It will primarily be stored in muscle and the liver. There will be certain factors that trigger bodily reactions to mobilise the glycogen. When we start exercising, the glycogen in our muscles will be the predominant source of energy. The liver will begin a process called glycogenolysis, where it will convert glycogen to glucose, so that the body can use it as energy to fuel its activities.
So, carbohydrates have become a bit of dirty word in some health circles, and there has been a rise of low-carb diets. But something that we need to realise is that carbohydrates actually serve some really important functions in our body.
- It is our primary energy source
We’re probably all familiar that it is our primary source of fuel, especially for those of use that engage in endurance activities. Carbohydrates provide energy for our muscles to contract continually, which is important for exercise. But the caveat is that if we consume too much, and it exceeds our cell’s capacity to use it, it will be stored as fat.
- Saves our protein
When the body runs out of carbohydrates, it will find the next available source, which will be our protein. We will discuss proteins in a future blog, but when we get to the point of starvation that the body has to start breaking down proteins, it will lead to bad circumstances, such as a loss of lean tissue mass, stress on the kidneys and excreting unhelpful by-products into the bloodstream.
- It gets our metabolism going
Carbohydrates help with our ability to oxidise (“burn”) fats. When we exercise too much or if we have inadequate levels of carbohydrates, it leads to the rate of fat mobilisation to exceed that of fat oxidisation. When fat breakdown is affected, ketone bodies (acetoacetate and B-hydroxybutyrate) get created, which may increase the acidity of your blood, leading to acidosis, which leads to a cascade of negative effects to the body.
- It’s food for our brain
Our brain and spinal cord need carbohydrates to function properly. Glucose is the main source of energy for blood cells and for metabolism of nerve tissue. That’s why when we see someone experiencing hypoglycaemia (low blood sugar), the symptoms include weakness, mental confusion and dizziness. Further severe cases of hypoglycaemia can cause someone to become unconscious and lead to irreversible brain damage.
There’s a lot more in-depth science to explore behind everything that goes on with macronutrients, but for this post, if we can understand what carbohydrates are and why they’re important, we’re doing well! 😊 See you at the next blog!
-Andrew
Social Exercise Project 