With so much hype surrounding low carb diets for weightloss, thousands of Australians are ditching bread and pasta for salads and smoothies.

And while some carbs are okay to cut from the diet, healthy carbs like fruits, vegetables and wholegrain cereals are optimal for optimal brain and body function.

So what are the signs your diet is too low in carbs and how much should you be eating per day to stay in shape?

'If you are consuming less than 80g of total carbs each day but doing a lot of exercise, your carbs will be too low to actually metabolise body fat,' Dietitian Susie Burrell (left) said

1. YOU ARE EATING WELL BUT NOT LOSING WEIGHT

'If you are consuming less than 80g of total carbs each day but doing a lot of exercise, your carbs will be too low to actually metabolise body fat and your metabolic rate will slow down over time,' Australian dietitian Susie Burrell said.

'The average female will require at least 120-140g of carbs if they are exercising regularly and sometimes our amounts are a little on the low side.

'Start by adding 10-20g of extra carbs via a piece of fruit, bread or 1/2 cup of wholegrains to the meal straight after exercise to slightly increase your carb intake and support fat loss.'

2. YOU FEEL TIRED THROUGHOUT THE DAY

While it's common to feel fatigued due to stress or a demanding schedule, a low carb diet could also be to blame.

'If you are exercising regularly and consuming inadequate amounts of carbs you will be left feeling lethargic and lacking the energy you usually have to go about your day to day life,' Ms Burrell, the founder of Shape Me, said.

'The reason for this is that your naturally energy systems have been altered which may in turn impact your blood glucose control. Fluctuating blood glucose levels can result in headaches, and inability to concentrate and a general feeling of lethargy.'

'If you are exercising regularly and consuming inadequate amounts of carbs you will be left feeling lethargic and lacking the energy you usually have,' Ms Burrell said

What are the recommended dietary intakes for average adults? Protein Men: 65-80g per day Women: 45-60g per day Fat 30 per cent of total energy intake - so on average 70g per day Carbohydrate 45-65 per cent of total energy intake - so an average of 230 - 310g per day Calcium 1,000mg per day Women 50+: 1300mg per day Men 70+: 1300mg per day Fibre Men: 30g per day Women: 25g per day Saturated Fat Less than 10 per cent of your total energy intake - so less than 24g a day Sodium 920-2300mg per day. A limit of 1600mg for people with heart disease Iron Women 19-50: 18mg per day Women 50+: 8mg per day Men 19+: 8mg per day Source: Healthy Food Guide Advertisement

3. YOU CRAVE SUGAR

Many office workers succumb to the dreaded mid-afternoon sugar craving or a strong desire for sugar straight after finishing lunch.

But this could be the result of too few carbs eaten throughout the day.

'Regular cravings after a meal may be a sign that your meal does not contain a balance of carbs and proteins that you need for fullness and satisfaction which can result in extreme feelings of hunger,' Ms Burrell said.

'Fluctuating blood glucose levels can also leave you feeling extremely hungry even when you have eaten only an hour or two previously as the body identifies that you have not taken adequate amounts of carbohydrate on board.'

'Regular cravings after a meal may be a sign that your meal does not contain a balance of carbs and proteins that you need for fullness and satisfaction,' Ms Burrell said

4. YOU ARE 'CLOGGED'

Fibre is key for healthy internal operations, with high carbohydrate foods likw fruit, starchy vegetables and breads all rich sources of dietary fibre and important elements of the daily diet.

So if these foods aren't being eaten, fibre intake is likely too low.

'In addition when your gut has been used to you consuming these foods regularly, and suddenly finds that it is no longer receiving significant amounts of wheat based fibres it can significantly impact the total amount of bulk moving through the gut,' Ms Burrell said.

This can cause 'significant reductions in transit time' of food which can result in constipation and much less frequent bowel movements in general.

5. YOU HAVE BAD BREATH

This is a little known side effect of a low carb diet - and a sign you need to up your intake.

According to Ms Burrell, when carbohydrate intake drops below a certain level, the body will make ketones, which is an 'alternate fuel source for the liver and the brain made from fat stores'.

'Ketones have a very distinct smell, some of which will be secreted through saliva if you are in ketosis,' she said.

'Often evident when you have trained after consuming very little carbohydrate for a day or two, the smell is far from pleasant and may suggest you could benefit from a little more carbohydrate in your diet.'