Low carb or slow carb?

Nutritionalist Sarah Burkhart discusses the issues surrounding carbohydrates and why they are an important part of any athlete's diet.

Carbs are critical to brain and muscle function

The good news for pasta and rice lovers is that a lot of the information out there is not scientifically correct and carbs are in fact a vital part of your diet – especially as an athlete - but you need to know which are the best ones!

Carbohydrates are a primary fuel source for the body. When a carbohydrate food is eaten, the food slowly breaks down through the stomach into smaller simple sugars.

Once these molecules of glucose are passed into the small intestine they are absorbed through finger like projections into the bloodstream.

Once the glucose is in the bloodstream it is termed your blood glucose or blood sugar. This glucose is transported by the blood around the body for different purposes.

Our brains need carbs

The brain (the area responsible for all of our bodily processes) relies on glucose as a fuel source. As it is so well protected in the skull, by a blood-brain barrier, the brain cannot rely on protein or fat as a source of energy.

With limited brain fuel you can imagine what occurs – the brain starts to slowly shut down – you start to feel a bit grumpy, you find it harder to concentrate, your reaction time is decreased and even simple tasks seem to take a huge effort to perform.

Our muscles need carbs

The glucose is also transported to the muscles to be stored as glycogen. This storage of glucose as glycogen can be likened to filling your car's fuel tank – you are filling your muscles with fuel for them to perform. When this glycogen is stored, around 3 grams of water is stored with each gram of glucose. When you exercise these stores of energy are used as fuel. A small back up supply is kept in the liver to be used if needed.

Not all carbs are equal

Carbohydrates are found predominately in the breads and cereals group, and the fruit and vegetables food group. They are not equal – refined carbohydrates tend to have a high Glycaemic index (G.I) – which means they are digested quickly and get you a quick hit of energy that tends to drop away quickly. The release of glucose into the bloodstream happens quickly.

A good example is bread – white bread has been refined, it has a high G.I, and because it has been refined it's lost a lot of its nutrients.  Wholegrain bread has more nutrients, more fibre and is lower G.I. – the rise of blood glucose is not as quick or as high but is more sustained. You should be trying to eat wholegrains breads and cereals as much as possible, and having a diet high in fruit and vegetables.

Dangers of low carbs for an athlete

One of the worst things an athlete can do is to a low carb diet – carbs are such a vital part of performance as they provide the fuel the body needs. Restricting them limits your fuel supply.

Any quick reductions in body weigh from a lowcarb diet are not due to fat loss but are because you use the glycogen stored in the muscle (also using up the 3 grams of water stored with it). On the scales this seems like you have lost weight but as soon as you start eating carbs again the weight will go straight back on (due to the water being restored with the carbs).

If you are looking to perform at your best carbohydrates are a necessary part of your balanced diet!

March, 2010

More articles on nutrition for cyclists  ....

 

About Sarah Burkhart....

Sarah is a Sports Nutritionist who is known for her practical and realistic approach to improving performance and getting results with athletes from recreational to elite international level. She has a BSc majoring in Human Nutrition and Physiology, and has just completed a MSc in Human Nutrition. 

She is a SESNZ Sports Nutrition Practitioner, the Sports Nutritionist for the Massey University Academy of Sport and a guest lecturer for Massey University. Sarah works in private practice providing services in the Wellington, Manawatu, Wairarapa and Taranaki areas in person, and New Zealand wide through her online consulting plans.

 

Sarah is also a keen road cyclist in her spare time. You can find out more at www.sportsnutritionist.co.nz or email her at  This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

 

 

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