What happens to your body when you limit carb intake, according to nutritionist

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Carbohydrates are often painted as the enemy, but in reality, our bodies need them - despite what popular diets suggest.

In their most basic form, carbs provide energy for the body - which is then used to fuel muscles, the brain and the central nervous system.

When carbs are cut, the result is typically weight loss - however, there are other negative side-effects that diets promoting the weight-loss tactic often overlook.

To understand what happens to your body when you cut back on carbs, we spoke to nutritionist and founder of Not Your Average Nutritionist Libby Parker, MS, RD - who told us: “Cutting way back on carbohydrates is very harmful for our bodies."

“The human body is designed to run primarily on carbohydrate sources, which ideally make up 45 to 65 per cent of our caloric intake,” she said.

So when an extremely low-carb diet is attempted, these are the risks.

Certain body parts are at a greater risk

According to Parker, when a diet such as the ketogenic diet is followed, which limits carb intake, certain body parts are more affected than others.

“There are certain cells in the body, including cells in our eyes and kidneys, that run exclusively on carbohydrates,” Parker said, before explaining that ketone bodies, which “are present in extremely low-carb diets like keto,” are not a sufficient replacement.

In general, low-carb diets often lead to a “lack of vitamins, minerals, and other compounds that we can only find in carbohydrate-rich foods like fruits and vegetables,” Parker said.

Because, in addition to the simple carbs found in breads, pastries and pastas, otherwise known as refined carbohydrates, carbs are found in a majority of foods - including many fruits, vegetables, and nuts.

There are also long-term risks - including a risk of colon cancer, constipation from lack of fibre, which is found in carbs, and kidney stones, according to Parker.

Low-energy

In addition to putting the body at risk, a low-carb diet also means less glycolysis, the breakdown of glucose for energy.

Although replacement energy can be found in the subsequent ketone bodies, it can leave a person feeling lethargic and slow-moving - otherwise known as "carb flu".

“Low-carb diets often cause lethargy, lack of endurance, brain fog, and inability to concentrate,” Parker said of the common flu-like feeling that occurs when you cut out carbohydrates.

Bad breath

Bad breath is also a lesser-known unfortunate side-effect of a low-carb diet.

According to Parker, bad breath is the result of acetone energy, one of the three ketone bodies, that occurs when the body enters ketosis.

And the problem cannot be fixed with toothpaste or mouthwash - as the only way to remedy it is to reintroduce carbs into the diet.

Disordered eating

While all dieting can result in compromised relationships with food and eating, Parker told us that keto variations can make a person particularly susceptible - as the diet is “very difficult to adhere to, especially when eating socially.”

And if the diet is properly followed, it may lead to social isolation, according to Parker.

To follow to a very low-carb diet in a “healthy” way, Parker advises doing so with a team of “specialised medical professionals” that check ketone levels frequently through daily blood glucose and ketone checks.

“If you don’t do needles, this is not for you,” she said.

Overall, Parker does not recommend following a very low-carbohydrate diet, or any restrictive diet - as the risks are too great

“Any restrictive diet can set you up for medical issues, potential eating disorders, and rebound weight gain as soon as you inevitably ‘fall off the wagon’ because diets do not work,” she said.