5 things you should know about sugar
Sugar is the buzz word in health right now. There are many who argue sugar is the true cause of the obesity epidemic; that sugar – not fat – is making us fat; that most diet trends are doomed to fail because they tend to be saturated in sugar; and that this sweet ‘natural’ substance is wreaking havoc on our overall health, leading to all kind of diseases and even several forms of cancer.
These people have really caused a stir among health professionals as well as the health conscious. The Australian Dietary Guidelines were updated recently. These guidelines are used by health professionals, policy makers, educators, food manufacturers, food retailers and researchers. One of the key differences in the revised Australian Dietary Guidelines was the inclusion of the recommendation to ‘limit intake of foods and drinks containing added sugars’.
Before you delve further into the revised Australian Dietary Guidelines, there are probably five things you should know about sugar.
1. The difference between ‘real’ sugars and the sugar in food
I was never very good at chemistry, but I get that everything in this world is made up of unique combinations of ‘base ingredients’ (for want of a better term). The same is true for sugar. In its purest form, there are three types of sugar:
- Glucose – the most important sugar to humans and found in every food except meat, which is eventually converted into glucose by our digestive system
- Galactose – present in our environment in small quantities and found mainly in dairy products in the form of lactose
- Fructose – relatively rare in nature and found in ripe fruits. It’s about 60% sweeter than glucose and galactose.
You might have heard of the above terms before, but it is more likely you would be familiar with the three commonly known sugars:
- Sucrose – made up of equal parts glucose and fructose (e.g. table sugar)
- Lactose – made up of equal parts glucose and galactose (e.g. the sugar in milk)
- Maltose – made up of two molecules of glucose joined together in an unusual way (e.g. the sugar in beer).
2. How the body breaks down sugar and controls sugar levels
When you understand how the body processes sugar you can begin to appreciate the challenges faced by diabetics, whose bodies produce little or none of a vital hormone that detects and manages the body’s fuel supply. Lesson: don’t ever take your body for granted.
- The pancreas produces the enzymes that break down our food by separating molecules
- The pancreas also produces the hormones that control the amount of glucose in our bloodstream and monitor blood-glucose levels. One of those hormones is insulin
- Insulin regulates processes in the digestive system by entering the bloodstream, usually after we have just eaten, and inducing a fullness signal (but it’s a fairly dull signal – you could still choose to ignore it, and the feeling usually only lasts about one hour).
3. How the body accesses sugar for energy
The body runs a tight ship. Every hormone, organ and muscle has a vital role to play. I have tried to keep this explanation as simple as possible! When it comes to managing energy, the key players are insulin (hormone), the liver (organ) and glycogen (hormone).
- When we eat, our blood-sugar (glucose, galactose and fructose) levels rise
- The body largely relies on glucose for energy, which is lucky because it’s in nearly everything we eat (except meat, which is eventually converted into glucose anyway)
- Insulin reduces blood-sugar concentrations by absorbing glucose and converting it to energy – this is the body’s preferred method of seeking and using energy (or fuel). Without insulin, most cells in the body wouldn’t be able to access the energy stored in glucose (except the brain – its neurons, or cells, suck up glucose direct from the bloodstream)
- If there is a lack of insulin and your body can’t ‘see’ the glucose, it will begin to convert its fat and protein stores into an alternative fuel called ketones. This method of burning fat for energy is the basis of the Atkins Diet, or any other high protein, low carbohydrate diet. It’s OK for the short-term, but in the long-term a build-up of the by-products from ketone production will lead to widespread tissue damage and multiple organ failure.
4. How the body stores sugar and manages the excess
I always thought it was better to eat sugar than fat because the body burns sugar more easily than it burns fat. It’s true the body burns sugar first, but what I didn’t know was that sugar is in nearly everything we eat, and that sugar – as with all the foods we eat – must first be broken down into pure glucose.
- The body can store about four hours’ worth of energy as glucose in our bloodstream
- The body can store a further 20 hours’ worth of energy as a form of solid glucose, called glycogen, around the liver and muscles
- Galactose is absorbed via the intestines and fructose – well, we’ll get to that in a minute
- The liver manages, recharges and discharges our short-term energy storage (it also acts as a filter for your body, cleaning the blood supply by removing excess nutrients and poisons absorbed through the stomach and intestinal walls). The liver engages insulin to suck out excess glucose from the bloodstream to convert and store it as glycogen
- Glycogen helps even out our energy requirements and restores blood-glucose levels to a normal range, so if we go without food for more than four hours our brain and internal organs can still function
- Glycogen also instructs the liver to convert amino acids (the component parts of proteins) into glucose and tells our fat cells to release energy. When the time is right, the liver converts glycogen stores back into glucose for energy.
- Any excess energy (in the form of glucose) is stored by the body as fat.
5. How sugar affects appetite control
I could never understand how I could eat so much chocolate (or so much fruit salad) and no matter how much I ate, or how full I was, I could always keep going. It’s like they say – there is always room for desert. This is why:
- We have one primary appetite-control centre in our brain – the hypothalamus
- The hypothalamus reacts to four major appetite hormones – insulin, leptin, CCK and ghrelin
- Ghrelin tells us when we need to eat
- Insulin, leptin and CCK let us know when we’ve had enough to eat
- Once circulating insulin is used up, the body will rely on leptin to let it know when it’s had enough food. Leptin is the body’s longer-term means of appetite control
- Leptin is produced by fat cells in response to circulating insulin – the more insulin in your bloodstream, the more leptin will be produced. Likewise, the more fat you have the more leptin you will have in your bloodstream. High levels of fatty acids in the arteries block the action of leptin
- While glucose (one half of what makes up regular table sugar) is used effectively and efficiently as energy, fructose (the other half of what makes up regular table sugar) bypasses all our appetite control systems and jumps a critical step in our metabolism
- Because the body can’t metabolise fructose for energy, it is converted and stored as fat. However unlike regular fats (consumed via meat, avocado, nuts, etc) which are readily detected and responded to by our appetite control mechanisms, fructose is not. That’s why we can consume so much of it and not experience a sense of fullness
- Effectively, when we consume sugar (table sugar), half of what we eat will very quickly be converted to and stored as fat.
As I said earlier, I was never a fan of chemistry. The information above simplifies the process of sugar absorption to the extreme, but, as I am sure you would understand, there is a lot more science to it! If you are interested about the process of sugar absorption and the health implications of high-sugar diets, I can recommend some further reading on sugar here.
Please be aware too that I am not a health professional and the information contained here is based on my own research. You should consult your physician if you have a medical condition or are considering a significant change in your diet and lifestyle.