That low-carb diet may have given you a more attractive figure, but it may not be so beneficial when it comes to your breath.

Dieters on extreme low-carbohydrates eating regimes, such as the Atkins diet, are more likely to suffer from halitosis, or bad breath, warned Dr Leong Hon Chiew, a dental surgeon at Dr H C Leong Dental Surgeon LLP.

Such diets restrict the daily intake of carbohydrates, such as grain-based foods.

As your meals are low in carbohydrates, the amount of protein and fat consumed will be proportionately higher, said Ms Natalie Goh, a dietitian at Peaches and Pear Nutrition Consultancy.

When carbohydrates - our body's main source of energy - aren't available, the body switches to burning body fat and protein for energy, explained Ms Goh.

This process causes certain chemicals, called ketones, to be secreted through the urine and lungs.

"The odour you smell is something that comes straight from the lungs," said Dr Leong.

Dr Leong added that typical bad breath caused by oral hygiene problems - such as bacteria in the throat or at the back of the tongue - has a sulphurous smell.

On the other hand, the breath of a person on a low-carb diet tends to smell like acetone, which is similar to the smell found in nail polish removers and paint thinner.

Other short-term effects of a low-carb diet include fatigue, poor concentration and dizziness.

"Without adequate carbohydrates, the body runs low on fuel. As energy reserves deplete, it is not unusual for low-carb dieters to feel tired and dizzy," Ms Goh explained.

She added that although dieters may experience rapid weight loss initially, most of it is due to water loss.

Unlike halitosis caused by oral hygiene problems, Dr Leong said bad breath that occurs as a result of a metabolic imbalance is tough to eradicate, even with the best oral health practices.

"You can try minimising the problem by drinking enough water or sucking on mints. But these measures only mask the bad breath," he said.

The good news is that once you go off your low-carb diet, this type of bad breath problem will be eliminated.

"The effect will be almost immediate. As long as your body stops having to break down fat and protein into energy, your breath will be back to normal provided you have no other underlying dental problems," said Dr Leong.

Losing weight is a matter of eating sensibly.

Stick to a diet that is low in calories, and high in dietary fibre from vegetables, fruit and wholegrain products, Ms Goh advised.

Consuming dietary fibre is helpful for those who want to lose weight because it "gives bulk" to their meal. That, in turn, helps to satiate the appetite.

One's carbohydrate intake should make up about 50 to 55 per cent of one's total calorie intake, while the proportion of protein and total fat should be about 15 to 20 per cent, and 25 to 30 per cent, respectively, Ms Goh recommended.

"Losing weight is about cutting down on total calories. If a person's diet is high in fat, he should focus on cutting down on fat first," she said.

Why? This is because 1 gramme of carbohydrates provides only 4 calories while the same amount of fat contains 9, more than double the amount of calories, Ms Goh explained.

Just how bad is your breath?

Most people try to find out if they have bad breath by cupping their hands over their mouths and smelling their exhaled breath.

But this method is rather useless, according to dental surgeon Dr Leong Hon Chiew.

"It's quite impossible to tell if you have bad breath by yourself. Your nose get acclimatised to the odour. Whatever (bad) smell is in your throat or mouth, your nose, which is mere inches away, will get used to it," Dr Leong explained.

A foolproof way of finding out if your breath stinks? "Ask someone you trust," said Dr Leong.

- TODAY/yb