No carbs, no concentration: How rice, pasta and potato make you smarter

Don't be so hasty to quit grains and fruit – it turns out that not only do carbs give us energy for our workouts and general functioning but our brain is totally reliant on them, so if you don't get enough you'll be super vague.

In fact, if we don't get enough carbs, our brains will start breaking down our muscles and organs to keep us alive.

"The brain and nervous system as a whole is highly dependent on glucose [from carbs and sugars] as a fuel source," explains Dr Alan Barclay, spokesperson for the Dietitians Association of Australia. 

"Your brain uses about a third of your daily carbohydrate intake. If you start cutting it back you are restricting the fuel supply and you just can't think straight."

Some food regimens, such as paleo and quitting sugar, can be pretty strict on carbs but Dr Barclay says you run a real risk of becoming a space cadet.

"Some say don't eat grains others say don't eat legumes, and both of these are a source of carbohydrate," Dr Barclay says.

"Often the only fruits they recommend are berries, but they are actually low in carbohydrates."

Many people will spruik quitting carbs as the ticket to weight loss, but Dr Barclay says it's often a case of "mistaken attribution".

"They have cut out a lot of food and drinks and as a consequence have lost weight, but it wasn't necessarily because of the carbohydrate per se – it was because they have cut out a whole range of foods and have cut their calorie intake," he explains.

Dr Barclay says that most of the low carb diets have been studied for no more than two years, which makes it difficult to know the long-term health implications of following them.

"There are fears of increased risk of long term health problems, including cancer," he says.

You need a minimum of 50g of carbohydrate a day, which is about the equivalent of four slices of bread to keep our brains ticking, according to Dr Barclay.

"If you're not eating enough carbs, you will break down your muscles and organs to create the protein required to produce carbohydrate – and that's really not a good thing," he explains.

"If you lose your muscles and organs, your metabolic rate slows down and it makes it easier to put on weight."

And long-term, a low-carb approach is highly likely to backfire.

"Most of the research shows that you might be able to stick to these diets for six or 12 months but it tends to interfere with your social life and family, plus it can be expensive," Dr Barclay says.

"Food is part of our cultural traditions so most studies show that after 12 months most people have gone back to their old eating habits. When you do, if you've lost muscle mass and slowed down your metabolism, you're going to put on more weight ultimately than you had in the first place."