Cutting out the carbs may help you lose weight-but it can also help you lose your memory.
Dieters who avoided starchy foods do worse in mental tests than those who allowed themselves pasta, bread and potatoes.
Scientists found that the mental performance dropped after just a week on an Atkins-style diet. The study demonstrates that the food you eat can have an immediate impact on cognitive behavior.
The popular low-carb and and non-carb diets have the strongest potential for negative impact on thinking and cognition.
The Atkin’s diet, popular in the early 2000s, bans carbohydrates such as flour, sugar and potatoes, but allows protein and fat. Some fruit and vegetables are also restricted.
Scientists believe that lo-carb diets reduce the amount of glucose, or blood sugar, which is carried to the brain and used by nerve cells for energy.
A low-carb diet means less fuel to power brain cells.

A new once-a-day weight-lose pill can help woman drop two dress sizes in six months, British scientists have said.
A survey revealed women spend 10 years of their lives dieting.
Scientists have admitted they were astonished by trials on tesofensine, which could be on the market in three years.
By targeting the part of the brain that controls appetite, it makes the user fell full soon after starting a meal and cuts the urge to snack.
Taken for six months, it is said to help achieve an average weight loss of 9.5kg – twice the amount achieved by any obesity drug now on the market.
But there is a worrying list of side-effects – mild nausea, diarrhoea, constipation and increase heart rate.
Future trials will be held to determine whether the side-effects outweigh the benefits.
Meanwhile, a study by LIPObind, a company that makes natural weight-loss supplements, polled 4000 British women and found a third started dieting aged 16 or under.
It said the typical woman will go on two diets a year, each lasting on average five weeks.
That ads up to 104 diets from age 18 to 70, a whopping total of 10 years.
One in 10 women spend 25 years or more dieting.
But while each diet sees an average drop of 2.8kg, a quarter lose nothing at all.
Thirty-nine per cent said they dieted because they were embarrassed about their looks.
The same number admitted being shy when stripping off in front of their partner.
And a shocking 25 per cent would be willing to to under the knife to get rid of extra kilos.