The Telegraphreports that mental agility expert Tim Forrester, who runs the brain training website cannyminds.com, believes the brain burns 90 calories an hour when it is doing something challenging like solving puzzles or working crosswords.
"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.
Now if they could just combine exercise with a puzzle solving task we might be able to make our workouts more effective. The Wii Fi could be a step in this direction.
The picture on the right is the cover of the People Celebrity Puzzler Superbook, which likely burns less calories than the New York Times crossword puzzles.
The Telegraph 
