CAN YOUR BRAIN BURN ENOUGH TO MAKE YOU SLIM?
Compared to loafing on the sofa in front of the Kardashians, trying to concentrate on serious mental tasks can feel physically exhausting. You feel like all those turning cogs must be having some impact on your energy stores. But does your brain actually burn more calories when it’s hard at work than it does during your weekly Netflix binge? The short answer is: yes. During a typical day, we burn about 1335 kilojoules just thinking. That’s like burning off a Mcdonald’s cheeseburger (1260kj) with 15 minutes of steady jogging – at 12km/h. According to Dr Ewan Mcnay, assistant professor of psychology and behavioural neuroscience at the University of Albany, our brains almost exclusively run on glucose – sugar. Unlike some other parts of our bodies, our brains need sugar, which is why when you cut carbs, you can feel mentally groggy and bad-tempered. So it figures that the harder they work, the more glucose they need. In fact, our brains use about 20 per cent of the body’s overall energy – despite them weighing 2 per cent of our total body weight. Dr Mcnay told Time.com that when you’re trying to memorise something, for example, the parts of your brain responsible for memory start to consume more energy. “You will, in fact, burn more energy during an intense cognitive task than you would veging out watching Oprah or whatever,” he said. However, the difference in calorie consumption between tasks is pretty minimal – at about 5 per cent. Most of the energy our brains use is in keeping us alert and ready to take in everyday environmental information, rather than individual thoughts. Someone who spends their working day deep in thought (like say, a mathematician or surgeon or actor learning lines) might burn about 400kj more than someone sitting in front of the TV for eight hours. Dr Mcnay says your best bet for increasing energy burn is to engage your brain in multiple senses, like eight hours of learning a musical instrument. And even then, as the glucose stores get used up, our minds start to wander – and if you tried to replace any of that glucose, you’d be consuming more than your brain would be burning.