Mental exercises such as puzzles and quizzes are said to burn an average of 90 calories every hour – more calories than are contained in a jammy dodger or a chocolate hobnob.
Mental agility expert Tim Forrester from brain training website cannyminds.com which published the claims, said giving the brain a workout burns calories in the same way that giving the body a workout does.
Superdiets 'based on myths' "Our brains require 0.1 calories every minute simply to survive," he said. "When we do something challenging such as a puzzle or a quiz we burn through 1.5 calories every minute."
The brain is made up of millions of neurons which communicate with other neurons, transmitting messages to the body.
Neurons produce chemicals called neurotransmitters to relay their signals.
These neurons extract 75 per cent of the sugar glucose, available calories and 20 per cent of the oxygen from the blood to create these neurotransmitters.
So undertaking activity such as difficult crosswords or challenging sudoku’s means your brain will need more glucose and more calories.
Eight-time World Memory Champion Dominic O'Brien said brains needs work outs just as much as bodies.
"Just as you need to continually exercise your body to stay fit and healthy you also need to exercise your brain and memory to remain mentally agile," he said.
* Snacks you can enjoy which have the same calories as an hour's brain workout include:
A chocolate chip cookie = 56 calories
A jammy dodger = 85 calories
A custard cream = 57 calories
A chocolate hobnob = 79 calories
* But if you carried on for two hours with a puzzle you could enjoy:
A pack of Hula Hoops = 175 calories
A bag of Maltesers = 186 calories
A creme egg = 173 calories
A bag of jelly babies = 180 calories