Does Thinking Burn Calories? What Gum and Shivering Cost, and Why Crying Has No Number

Thinking burns very little extra. The best measurements I found put reading at about 4 kcal an hour above rest and a lab stress test at 12.3% above rest. The short answer to “does thinking burn calories” is a small yes. Chewing gum adds a few calories an hour. Shivering adds dozens. Nobody has measured crying.

Every figure comes from a paper or table I opened, and each conversion is shown. Where nothing was measured, I say so. Sums use a 2,000 kcal day as the yardstick.

Does thinking burn calories, even when the task is hard?

A little, and too little for whole-brain measurements to pick up. Start with the brain at rest. It is about 2% of body weight, yet it accounts for about 20% of the oxygen and calories the body consumes. Marcus Raichle and Debra Gusnard published that estimate in PNAS in 2002, and it is the number behind the whole question. The paper gives it as a share of everything the body consumes, not as the cost of any one task.

Here is what it means in kilocalories. The Compendium of Physical Activities puts resting cost near 1 kcal per kg of body weight per hour. I use it as a stand-in. At 70 kg (154 lb) that is 70 kcal an hour and 1,680 kcal over 24 hours. Twenty percent of 1,680 is 336 kcal. Your own resting rate will differ, so read 336 as an illustration, not a reading of you.

The same paper has the part that matters here. The authors call the brain’s energy use steady across very different levels of mental and physical activity. They report that attempts to detect a change in whole-brain blood flow or metabolism during intense mental activity have found none. They put that down to the accuracy of the methods and the small size of the changes. Local blood-flow changes during most cognitive tasks are often 5% or less.

Push that to its limit. Suppose the whole brain worked 5% harder for a full 24 hours, which nobody has shown. That adds about 17 kcal (336 × 0.05 = 16.8). Generous, and still small.

For hard tasks, the best numbers come from activity tables and small trials rather than brain scans. The 2024 Adult Compendium has the numbers I wanted. Sitting quietly is 1.0 MET, computer work while sitting is 1.3, and a seated chess game or sitting and studying is 1.5. One MET is about 1 kcal per kg per hour. The extra over sitting still is 0.3 or 0.5 times your weight in kilograms, per hour. I worked it for three body weights.

Activity (Compendium code)	MET	Extra at 55 kg (121 lb)	Extra at 70 kg (154 lb)	Extra at 90 kg (198 lb)
Sitting quietly (07021)	1.0	0 kcal/h	0 kcal/h	0 kcal/h
Sitting, computer work (11582)	1.3	16.5 kcal/h	21 kcal/h	27 kcal/h
Chess game, sitting (09013)	1.5	27.5 kcal/h	35 kcal/h	45 kcal/h
Sitting, studying (09060)	1.5	27.5 kcal/h	35 kcal/h	45 kcal/h
Sitting, in class (09065)	1.8	44 kcal/h	56 kcal/h	72 kcal/h

The Compendium marks estimated values in red, and none of the codes above is red. Read these as upper bounds for thinking alone. A MET value covers the whole activity: posture, a hand on a mouse, shifting in the chair. The Compendium gives sitting quietly with fidgeting hands its own line, code 07022, and that line is also 1.5. Fidgeting alone costs as much as a chess game. No row separates the thought from the movement.

One randomized trial measured something closer to pure concentration. Snell and colleagues (2014) tested 65 healthy adults on an indirect calorimeter. Reading a magazine or a screen raised resting energy use by 102.7 kcal per day compared with resting. That is a daily rate. Divide 102.7 by 24 and you get about 4.3 kcal an hour. Listening to music raised it by 27.6 kcal per day, about 1.2 kcal an hour. Their own advice: don’t read during a metabolic test, because it nudges the result.

Stress is a separate case. In a small Swiss study, seven women with an average age of 33 did a 30-minute mental stress task while their insulin levels were raised. Their energy use ran 12.3% above rest, and 12.6% when they repeated it after a six-week exercise program. Seven people can’t set a rule. The lab conditions were unusual, and a stress test says little about calm concentration.

Put together, hard mental work adds anywhere from nothing measurable to the 35 kcal an hour that a chess-level rating implies at 70 kg. The top of that range probably includes movement. A two-hour exam at 70 kg comes to at most 70 extra kcal (35 × 2). Not much of a workout.

Does chewing gum burn calories?

Yes, a few calories an hour, and the three measurements I found disagree on how few. In a letter to the New England Journal of Medicine, Levine, Baukol and Pavlidis (1999) studied seven people whose weight was stable. They sat at rest for 30 minutes first. Each then chewed 8.4 g of calorie-free gum to a metronome for 12 minutes, and energy use rose by 11 kcal an hour. That was 19% above the resting 58 kcal an hour. Standing raised it by 11% in the same people. Walking at 1 mph raised it by 106%.

Kresge and Melanson (2015) used 30 people, 17 men and 13 women, with an average age of 21.5. Sugar-free gum, 1 hour in all, in three 20-minute sessions. Fasting energy use was 1.23 kcal a minute with gum and 1.17 without. Taking those rounded values at face value, the gap is 0.06 kcal a minute, or 3.6 kcal an hour. A second figure comes from the 3 hours after a breakfast shake: 1.46 with gum, 1.42 without. The chewing totaled only 1 hour, so I don’t treat that 0.04 kcal a minute (2.4 kcal an hour) as a rate for chewing.

A third measurement comes from van Casteren and colleagues (2022) in Science Advances. Twenty-one adults lay on a bed and chewed odorless, tasteless gum bases, a soft one and a stiff one, for 15 minutes each. Resting use averaged 4.27 kJ a minute. A soft base took 4.69 and a stiff one 4.91. Dividing the gaps by 4.184 kJ per kcal gives about 6.0 and 9.2 kcal an hour. The authors describe that as 10 to 15% above basal.

Study	People	Chewing time	Extra energy
Levine 1999	7	12 min	11 kcal/h
Kresge 2015	30	60 min in three sessions	3.6 kcal/h (fasting)
van Casteren 2022	21	15 min per gum	6.0 kcal/h (soft), 9.2 kcal/h (stiff)

Across the three, the range runs from 3.6 to 11 kcal an hour. Two hours of chewing a day would come to about 7 to 22 kcal. The Science Advances team ran a similar sum. With a human-like chewing time of 0.35 hours a day, they put the cost at 0.1 to 0.2% of daily energy.

Levine’s letter went further and projected a yearly loss of body fat from gum chewed through every waking hour, if nothing else changed. That is arithmetic stretched from a 12-minute test at a metronome-set pace, and the two later studies measured less. It is not advice, and I wouldn’t build anything on it.

One practical catch: a piece of gum has its own calories. Check the label. If a piece lists more calories than the few kcal an hour that chewing it uses, you come out behind.

Does shivering burn calories?

Yes, and shivering is the one item here that clearly moves the number. It is muscle contracting to make heat, and its cost has been measured more than once. In a 2026 randomized crossover trial, Hashim and colleagues put 24 sedentary adults aged 40 to 75 in a water-perfused suit for two cold sessions. The volunteers were recruited for a blood-sugar study, so they are not a typical sample. Mild cold (15 °C suit water) raised resting metabolic rate to 1.53 and 1.57 times its baseline in the final hour, for the two groups. Moderate cold (4 °C suit water) raised it to 1.94 and 2.09 times. Shivering was confirmed by indirect calorimetry and muscle recordings.

Peak shivering costs far more. In a Canadian study, Eyolfson and colleagues (2001) immersed 15 volunteers in 8 °C water for up to 70 minutes. Their mean age was 24.7 and mean weight 72.1 kg. The team then warmed the water to 20 °C, which they expected to provoke maximal shivering. Peak oxygen use was 22.1 mL per kg per minute, 4.9 times resting.

Now the conversion. The Compendium’s rule is 5 kcal per liter of oxygen. The sum is 22.1 × 72.1 ÷ 1,000 = 1.59 L a minute, or about 7.97 kcal a minute, near 480 kcal an hour. The paper measures a peak, so don’t multiply it by an hour.

For a 70 kg adult at the 70 kcal an hour stand-in, those multiples work out as follows. It is my illustration. The trials used measured resting rates, not my rule.

Cold exposure	Multiple of resting	Extra at 70 kg
Mild (15 °C suit), final hour	1.53 to 1.57	37 to 40 kcal/h
Moderate (4 °C suit), final hour	1.94 to 2.09	66 to 76 kcal/h
Peak shivering in cold water (a peak, not an hour)	4.9	about 273 kcal/h

Shivering is the body defending its temperature, and these were supervised lab sessions, not a method. If you shiver often while people around you are warm, mention it to your doctor rather than reading it as a calorie source.

Does crying burn calories?

I couldn’t find a measurement. I searched PubMed and Europe PMC for energy expenditure in crying. Both gave me newborn studies and nothing on adults. I also searched all 22 category pages of the 2024 Adult Compendium for crying, weeping, thinking and chewing gum. It has a line for laughter, sitting, at 1.0 MET, the same as sitting still, but no line for any of those four.

So any calorie figure you see for a good cry has no measurement behind it that I could find. I won’t guess one from laughter, because it is a different activity. That could change. A measured study of adults would settle it.

How much do these add up to in a day?

I set each figure beside a 2,000 kcal day, a round number for the sum and not a target for you. Every row is per hour except the first, which is per day. The sitting, shivering and walking rows are for 70 kg; reading and gum are study averages.

Item	Extra energy	Share of 2,000 kcal
Whole brain 5% harder, all 24 hours (ceiling)	17 kcal per day	0.8%
Reading	4.3 kcal	0.2%
Chewing gum	3.6 to 11 kcal	0.2 to 0.6%
Sitting, studying or chess (upper bound)	up to 35 kcal	1.8%
Mild shivering	37 to 40 kcal	1.9 to 2.0%
Moderate shivering	66 to 76 kcal	3.3 to 3.8%
Walking at 2.5 mph	140 kcal	7%

Walking gives the yardstick in the last row. Standing is another small change, and does standing burn more calories measures it. The Compendium rates walking at 2.5 mph on a level, firm surface at 3.0 MET. That is 2.0 METs above sitting quietly, and 2.0 × 70 kg gives 140 kcal in an hour. It is four times the studying figure. A 30-minute walk adds 70 kcal, which matches two full hours of the upper-bound studying number.

To get the walking number for your own weight and pace, the steps to calories calculator works from the same Compendium file. It separates your total from the extra a walk adds.

None of it is worth tracking. Your daily estimate already includes a resting brain and the sitting you do anyway, so adding them would count twice. That total is built in how many calories you burn a day. The brain keeps running overnight, and that cost sits in the calories you burn sleeping. Even the resting rate moves a little across the month, as the piece on whether you burn more calories on your period shows. For the one activity here you could actually plan around, see calories burned walking.

What should you do with these numbers?

Leave them out of your log. Don’t add calories for an exam, a hard meeting, a cry or a stick of gum, and don’t subtract them from a food budget either. If you chew gum, read the calories on the pack, since that number is the one you control.

Try this today. Pick one hour you will spend sitting and thinking and multiply your weight in kilograms by 0.5. That is the Compendium’s upper bound. Then multiply your weight by 2.0 for one hour of walking at 2.5 mph. The gap between the two answers shows where a day’s budget actually moves.

If your tracker or an article claims a big calorie number for something that only feels effortful, ask which study it came from. For crying I found none, and for thinking the ones I found were small.