Thursday, 25 July 2013

Does Fruit Make You Fat?

Recently someone told me not to eat fruit because fructose (the type of sugar in fruit) turns to fat! This is NOT true. Fruit is not the enemy and fructose, like all other sugars, in moderation will not make you fat. In saying that, excess sugar will cause havoc in the body and everyone should avoid processed food with a high sugar content, especially those which contain high fructose corn syrup (HFCS). In the USA HFCS is in everything because it’s cheap, super sweet and they love the taste. Thankfully, here in Australia HFCS is not added to foods, but check your labels because we do import from the USA. 

What exactly is sugar?

Sugar is the common name for a group of sweet flavoured simple carbohydrates. The simple carbohydrates include monosaccharides and disaccharides. The most common monosaccharides include glucose, fructose and galactose (milk sugar). When two monosaccharides combine they form disaccharides, for example when glucose and fructose join together they form sucrose, better know as table sugar. Lactose is another example of a disaccharide, made up of glucose and galactose. Fructose is the sweetest of the monosaccharides and is primary sugar in honey and fruit. Glucose is mildly sweet and galactose has little sweetness compared to fructose and glucose.

Simple vs complex carbohydrates 

All carbohydrates contain carbon, oxygen and hydrogen (think carbon and water C + H20). Simple carbohydrates are easy for the body to break down as they only contain one or two molecules. Simple carbs provide a quick energy hit and a sudden rise in blood sugar. Complex carbohydrates, such as starch and fibre, are made up of many monosacchraides (usually glucose) linked together and are called oligosaccharides and polysaccharides. Complex carbs can help regulate blood sugar and can help us to feel fuller for longer. Carbohydrates are essential for optimum health and can help minimize risk for disease, for example fibre can protect against bowel cancer and helps to reduce cholesterol levels.

How do we metabolise and store carbs?

Carbohydrates are broken down and stored in the body as glycogen. Glycogen is a polysaccharide. A third of our glycogen stores are found in the liver and the other two thirds are stored in our muscles. The muscles store most of our glycogen so it can be used as fuel during exercise. When our blood sugar is low, hormones send messages to release glycogen, which is rapidly broken down to glucose and then transported in our blood to organs, tissues and cells.

Carbs are essential for our bodies to function effectively. Importantly, glucose is the preferred fuel for our brain, nerves and developing red blood cells. Protein can be converted to glucose if the body is desperate for glucose, but this requires more energy and can cause muscle breakdown. In addition, protein is required for other purposes in the body, so it is essential to consume enough carbs so proteins can perform their required roles. To spare body protein we need at least 50 to 100 grams (bare minimum) per day, this depends on your activity levels, age and gender.

Carbs and weight management

If you think carbs are “fattening” and have been avoiding them because you are trying lose weight, you should consider a different approach. Of course this type of strategy will help those who have a high intake of simple carbs (sugar) such as soft drinks and sweets, but not for those who eat a balanced diet with a variety of carbs such as vegetables, fruits, legumes and whole grains.

Most people should try to consume 45%-65% of your total calories as carbohydrates. Eating whole foods such as fruit provide not only fructose, but also fibre and plenty of other vitamins and minerals. The Australian dietary recommendation’s urge people to select abundantly from carbohydrate rich foods

Finally, if you are not interested in all the sciencey stuff and just want to know if carbs are good or bad the answer is that carbs are good and absolutely essential for our body to function properly. However, remember that not all carbs are created equal, high sugar processed foods, what I like to call fake food, will not provide the benefits of natural carbohydrate rich foods.

Dr Denise Furness, PhD BSc RNut REP
Registered Nutritionist & Personal Trainer with Mill Park Leisure



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