Kathleen Couillard – The Rumor Detector
Agence Science-Presse (www.sciencepresse.qc.ca)
Does a grandmaster playing chess use up as many calories as a marathon runner? The Rumor Detector wanted to know if this rumor holds any water… and not just for chess players.
Facts to Retain
– Our brains are particularly active and energy-hungry.
– Nonetheless, a rise in energy consumption linked to certain mental tasks is minimal.
– Stress does burn calories, but not as many as we would imagine.
The Origin of the Rumor
At a 2009 conference at Stanford University in California, the neuroendocrinologist Robert Sapolsky mentioned that chess grandmasters burn up between 6,000 and 7,000 calories a day during a tournament. In contrast, an inactive person burns 1,200 to 1,400 calories per day.
And that’s not the first time Sapolsky claimed this: He developed the idea in his 1994 book Why Zebras Don’t Get Ulcers. He was conveying the results of a study by physicist and former chess champion Leroy Dubeck, who measured the breathing rate, blood pressure and muscle contractions of chess players during a game.
An article on the ESPN website in 2019 popularized this rumor. Sapolsky was interviewed. He specified that chess grandmasters had blood pressure rates as high as competitive marathon runners.
According to a Reddit user who apparently exchanged emails with Sapolsky in 2020, the endocrinologist explained that the figure 6,000 calories was extrapolated in a calculation made by Dubeck himself. Sapolsky apparently asked that ESPN mention that this number wasn’t a direct measurement, and that it shouldn’t be considered the “gospel truth” about the matter.
How to Estimate Energy Consumption
German neuroscientist Petra Rittern observed in a 2022 paper that Sapolsky’s contention was based solely on measurements of breathing rate, blood pressure and muscle contractions. But that even though these values were as high for chess players during a tournament as for athletes in competition, it shouldn’t be assumed that they all use the same amount of energy.
In reality, this data is generally not used to calculate a person’s energy output. The most precise way of doing that is to determine the heat exuded by the body, as the American researcher James A. Levine explained in 2007. It is also possible to estimate the energy consumption of a person in an indirect manner by measuring their oxygen intake and the CO2 they breathe out.
Energy and the Brain
True enough, the brain is a particularly active organ. Even when we daydream, Australian psychologist and researcher Oliver Baumann pointed out in 2023, the brain has to process sensory data from the environment, conserve memories, plan the future and manage emotions. Fully 20% of our daily energy consumption is attributable to brain functions.
Studies have shown that tasks like mental calculation, reasoning and multitasking are associated with an increase in oxygen consumption and therefore energy consumption, adds Oliver Baumann. For example, during a game of chess, players have to reflect upon a vast range of moves and make the best choice, which takes great mental effort.
But this increase in energy consumption is minimal, insist Baumann and Rittern. In fact, in 1955, a study demonstrated this by comparing people doing mental calculations with the same people who were left to daydream. Energy consumption was similar in both cases. That’s because the brain has several mechanism that economize energy. For example, when it processes visual information, it reduces its activity in auditory regions. The cost of visual attention is compensated by a diminution in auditory processes.
Therefore, reading requires only 5% extra energy. And eight hours of strenuous mental work only uses up 100 to 200 calories, Petra Rittern reports.
Does Stress Burn Calories?
Fatigue experienced during a demanding mental task is probably due to the whole body’s reaction to an emotional or stressful situation, explained Oliver Baumann. Because complex cognitive tasks are difficult to manage emotionally, they trigger activation of the sympathetic nervous system. This system is activated in times of stress to prepare the body to act on an imminent danger. This notably translates into an increase in adrenaline and a faster heart rate. Since a chess tournament provokes a large psychological stress, it can theoretically increase the energy expended.
Chess Players
In 2009 researchers tested this theory. They measured chess players for a variety of cardiac and respiratory parameters. During the games, they noted that chess players did indeed experience increased breathing rates, especially at the beginning of games, which activated the sympathetic nervous system. The scientists also used the opportunity to measure overall energy consumption during the game: just 138 calories.
Turkish researchers confirmed this in 2022. They evaluated the energy consumption of national and international level chess players in two different sets of circumstances: the first, during chess games; the second, during 30 minutes of running on a treadmill. On average, players burned 159 calories during a chess game and 283 calories while running.
Even if they are performing important mental work during a chess match, grandmasters use up less than 200 calories during a game. That is less than a high-level athlete, and far from the rumored 6,000 calories.
This article is part of the Détecteur des rumeurs series. Click here to see other articles in the series.
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