The first thing a lot of people eliminate when trying to lose weight is carbohydrates, but a new study review suggests they could increase our chance of early death by almost 30 percent.
Hiroshi Noto, from the University of Japan, reviewed 17 long-term studies into low carbohydrate diets and also found no heart health benefits from following a low-carb diet.
"Low-carbohydrate diets tend to result in reduced intake of fibre and fruits and increased intake of protein from animal sources, cholesterol and saturated fat, all of which are risk factors for mortality and cardiovascular disease," the authors wrote in the journal PLOS ONE.
University of Canberra nutritionist Professor Peter Williams said that a low-carb diet can be effective in the short-term, but appears to have health implications if people do it for a long period of time.
"In the short term , a year or so, there are some advantages from a low-carbohydrate, high-protein diet," Professor Williams told news.com.au.
Accredited practising dietitain Natasha Murray told ninemsn people mistakenly believe low carb diets are good for weight loss because they make us lose "water weight".
"We store carbohydrate in the body as glycogen, and for every gram we store, 1.6 grams of water is also stored," Murray said.
"When you are losing your carb stores from your muscles, you are also losing water weight. You hear of people saying, 'I have lost 5kg in one week' but most of that is water weight."
That weight can easily be regained when we resume a diet with carbohydrates.
"Carbs are not evil — we need them for energy," said Murray, who is a spokesperson for the Dietitians Association of Australia.
"Glucose from carbohydrates is the only thing the brain can use to work, so if you don't have carbs, your brain can be fuzzy."
Murray said it's possible the low-carb diets reduced people's life expectancy because of the lack of fibre, plus the fact people on low-carb diets are eating too much fat and animal protein.
"Whole grains and fruit contain fibre, which can protect against bowel cancer and other bowel conditions," Murray said.
"If we increase proportions of fat, it's likely we're also increasing the proportion of saturated, which has cardiovascular risks. You're also missing out on a lot of the phytochemicals that are contained in grains."
The National Health and Medical Research Council recommends carbohydrates make up between 45 and 65 percent of our daily diet.
Murray said we need to eat carbs, protein and vegetables for every lunch and dinner.
"Cover a quarter of your plate with whole grains, such as brown rice and pasta, or starchy vegetables," she said.
"The other quarter can be protein, then fill the other half of the plate with non-starchy vegetables. This is a great weight-management strategy."