Karpov's wasn't alone in experiencing the extreme physical effects of the game. While no chess competitor has experienced such profound weight loss since then, elite players can reportedly burn up to an estimated 6, calories in one day — all without moving from their seats, ESPN reported. Is the brain responsible for this massive uptake of energy? And does that mean that thinking harder is a simple route to losing weight? To delve into that question, we first need to understand how much energy is used up by a regular, non-chess-obsessed brain.
That translates to or calories per day for the average woman or man, respectively. During childhood, the brain is even more ravenous.
Boyer researches anatomical and physiological changes associated with primate origins. Humans aren't unique in this regard.
Together with Duke University evolutionary anthropology graduate student Arianna Harrington, who studies energy usage in mammal brains, Boyer conducted research revealing that very small mammals such as the tiny tree shrew and the minuscule pygmy marmoset devote just as much of their body energy to the brain as humans do.
Boyer believes the reason is that despite brains being lightweight, human brains — and the similarly glucose-hungry brains in tree shrews and marmosets — are large relative to the rest of the body.
Most of the energy hauled up by this organ is devoted to enabling neurons in the brain to communicate with each other, via chemical signals transmitted across cell structures called synapses, said Harrington. That involves a lot of transportation of ions across membranes, which is thought to be one of the most expensive processes in the brain.
In addition, the brain never really rests, she explained; when we sleep, it still requires fuel to keep firing off signals between cells to maintain our body's functions. Crying is typically a physical response to emotional stress, which sets off a chain reaction in the body. As described by the American Heart Association AHA , "Your body releases adrenaline, a hormone that temporarily causes your breathing and heart rate to speed up and your blood pressure to rise.
These reactions prepare you to deal with the situation. But though crying is a physical response, it is not physical exercise. It doesn't burn significant calories, nor is it likely to help you reach a weight-loss goal. As the AHA makes clear, the only muscle that emotional stress really "burns" per se is the heart. And even though your heart rate does speed up when you are sobbing due to grief or anguish, that increase isn't enough to have a significant impact on your metabolic rate — or result in weight loss.
Another point to consider is that mental and emotional stress can both result in emotional eating, which adds calories instead of burning them. Bottom line: If you are trying to lose weight, draining your energy by overloading your brain or emotions isn't going to produce results.
It might even make you overeat, or feel too worn out to engage in healthful forms of exercise. Frequent crying and changes in appetite are two signs of clinical depression, according to the Skidmore College Counseling Center. If you or a loved one have been experiencing them for more than a few days, talk to a mental health professional.
By Elizabeth Kuster Updated October 4, Both Gibson and Messier conclude that when someone has trouble regulating glucose properly—or has fasted for a long time—a sugary drink or food can improve their subsequent performance on certain kinds of memory tasks. But for most people, the body easily supplies what little extra glucose the brain needs for additional mental effort. Body and mind If challenging cognitive tasks consume only a little more fuel than usual, what explains the feeling of mental exhaustion following the SAT or a similarly grueling mental marathon?
One answer is that maintaining unbroken focus or navigating demanding intellectual territory for several hours really does burn enough energy to leave one feeling drained, but that researchers have not confirmed this because they have simply not been tough enough on their volunteers.
In most experiments, participants perform a single task of moderate difficulty, rarely for more than an hour or two. Equally important to the duration of mental exertion is one's attitude toward it. Watching a thrilling biopic with a complex narrative excites many different brain regions for a good two hours, yet people typically do not shamble out of the theater complaining of mental fatigue.
Some people regularly curl up with densely written novels that others might throw across the room in frustration. Completing a complex crossword or sudoku puzzle on a Sunday morning does not usually ruin one's ability to focus for the rest of the day—in fact, some claim it sharpens their mental state.
In short, people routinely enjoy intellectually invigorating activities without suffering mental exhaustion. Such fatigue seems much more likely to follow sustained mental effort that we do not seek for pleasure—such as the obligatory SAT—especially when we expect that the ordeal will drain our brains. If we think an exam or puzzle will be difficult, it often will be.
Studies have shown that something similar happens when people exercise and play sports: a large component of physical exhaustion is in our heads. In related research, volunteers that cycled on an exercise bike following a minute computerized test of sustained attention quit pedaling from exhaustion sooner than participants that watched emotionally neutral documentaries before exercising.
Even if the attention test did not consume significantly more energy than watching movies, the volunteers reported feeling less energetic.
That feeling was powerful enough to limit their physical performance. In the specific case of the SAT, something beyond pure mental effort likely contributes to post-exam stupor: stress. After all, the brain does not function in a vacuum. Other organs burn up energy, too. Taking an exam that partially determines where one will spend the next four years is nerve-racking enough to send stress hormones swimming through the blood stream, induce sweating, quicken heart rates and encourage fidgeting and contorted body postures.
The SAT and similar trials are not just mentally taxing—they are physically exhausting, too. A small but revealing study suggests that even mildly stressful intellectual challenges change our emotional states and behaviors, even if they do not profoundly alter brain metabolism. Fourteen female Canadian college students either sat around, summarized a passage of text or completed a series of computerized attention and memory tests for 45 minutes before feasting on a buffet lunch. Students who exercised their brains helped themselves to around more calories than students who relaxed.
Their blood glucose levels also fluctuated more than those of students who just sat there, but not in any consistent way. Levels of the stress hormone cortisol, however, were significantly higher in students whose brains were busy, as were their heart rates, blood pressure and self-reported anxiety. In all likelihood, these students did not eat more because their haggard brains desperately needed more fuel; rather, they were stress eating. Messier has related explanation for everyday mental weariness: "My general hypothesis is that the brain is a lazy bum," he says.
It's possible that sustained concentration creates some changes in the brain that promote avoidance of that state. It could be like a timer that says, 'Okay you're done now.
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