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Eating less can sharpen your thinking聽鈥 if you鈥檙e a worm, at least. We already had an inkling of the benefits of calorie restriction, such as聽greater longevity in flies, mice and monkeys. Now at the University of California, San Francisco, has found it may also boost the brain.
His team trained Caenorhabditis elegans roundworms to associate the scent of a chemical, butanone, with a food reward. The proportion of worms that migrated from the centre of a circle to one side laced with butanone, rather than the opposite side that smelled of alcohol, showed how well they had learned this lesson.
The worms tested had either eaten freely, or fasted for 1 hour, or had a calorie-restricted diet. The proportion of worms on a diet of half the normal calories that migrated was double that for those allowed to eat freely. The same was true for the worms that had fasted, suggesting low-calorie diets and short-term fasts have similar聽effects.
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Eating fewer calories may work by聽depleting a brain chemical called kynurenic acid, which in turn activates neurons involved in learning. When the team reduced kynurenic acid, the worms鈥 learning improved without calorie restriction.
There are signs of a similar phenomenon in mammals, says Ashrafi. A found that people around the age of 60 who cut their calories by 30 per cent were better at learning lists of words.
This makes evolutionary sense, says at the University of聽Sydney. 鈥淵our brain needs to be functioning at a high level when you鈥檙e on the hunt for food because you鈥檙e trying to beat competitors,鈥 he says. 鈥淥nce you鈥檝e had a big meal, you just want to sleep.鈥
But strong hunger has been found to impair cognitive function聽鈥 possibly because it makes us preoccupied with thoughts of food.
PLoS Biology
Read more: Hungry stomach hormone promotes growth of new brain cells
This article will appear in print under the headline “Learn better by counting your calories”
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