In the News: Low carbohydrate diets can starve the brain

Cutting out carbohydrates from your diet in an attempt to lose weight can lead to memory loss, according to a study published this month in the medical journal Appetite.


The study by scientists from Tufts University in Boston, America – which clearly demonstrates that the food you eat can have an impact on mental performance – found that dieters who avoided carbohydrates do worse in mental tests than those who are allowed some pasta, bread and potatoes. This is because carbohydrates are an important source of energy or fuel for the brain and mental performance drops after just a week on low carbohydrate diets. The aim of the study was to look at the impact of low carbohydrate diets on the brain power of 19 women aged 22 to 55. Volunteers were put on either a low calorie balanced diet or a low carbohydrate diet. Within a week ten women on the low carbohydrate diet were far worse at mental tests than those on a conventional balanced diet. The tests looked at attention, long term and short term memory, visual attention and spatial memory and the low carbohydrate dieters showed a gradual decline in memory tasks compared to the low calorie balanced dieters. Their reaction time was sluggish and their visual memory poor.


The researchers believe that low carbohydrate diets reduce the amount of blood sugar or glucose which is carried to the brain and used by nerve cells for energy. The brain needs a constant supply of glucose for energy and diets low in carbohydrates can be detrimental to learning, memory and thinking. Low carbohydrate diets can also be detrimental to long term weight loss because they are not sustainable in the long term and create nutritional deficiencies which can lead to blood sugar imbalances, mood swings and comfort eating.


What is not clear from this research is what they mean by low carbohydrate diets.  Fruit and vegetables are also carbohydrates and with the extreme high protein low carbohydrate diets these are also omitted along with starchy carbohydrates.  We do need carbohydrates for ‘brain energy’ but they need to be the right carbohydrates and we can easily omit the added sugar and white flour carbohydrates which will be better for our health generally and will not effect brain function negatively  In fact by not having these in the diet, it can often improve memory and concentration because the blood sugar is not fluctuating wildly. 

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