Did Einstein stay lean by burning calories with his brain?

Need to lose some flab? Sit your big butt down with a math book-and feel the burn. The human brain is a 24-hour workhorse. While you´re thinking, millions of neurons fire messages back and forth to each other and to the various tissues in the body. These neurons need fuel, consuming a full 75 percent of the blood sugar from the liver and 20 percent of the body´s total used oxygen. Here´s how your neurons feed: Astrocytes-the cells near the capillary walls in your brain-suck energy-rich glucose from the bloodstream and convert it into a form that the neurons can soak up. The neurons then use it to fuel the production of neurotransmitters and, eventually, conscious thought. â€The more energy an area of the brain wants, the more glucose that part of the brain will break down,†explains neurologist Harry Chugani of the Children´s Hospital of Michigan. â€So yes, if you´re thinking really hard and really struggling with your thoughts, the neurons in the frontal lobes of your brain will be burning a lot more glucose.â€

Simply to survive, your brain requires a tenth of a calorie per minute. Compare this with a walk to the doughnut shop, when your body burns approximately four calories a minute. Kickboxing zaps 10 calories a minute. And when you´re hunched over a crossword puzzle? Your brain is blasting through a respectable 1.5 calories a minute. Pass the Cheetos.