Scientific American: Psychology
From the Pages Activity

WHY DO WE CRAVE SWEETS WHEN WE’RE STRESSED?

A brain researcher explains our desire for chocolate and other carbs during tough times.

Although our brain accounts for just 2 percent of our body weight, the organ consumes half of our daily carbohydrate requirements—and glucose is its most important fuel. Under acute stress the brain requires some 12 percent more energy, leading many to reach for sugary snacks.

Carbohydrates provide the body with the quickest source of energy. In fact, in cognitive tests, subjects who were stressed performed poorly prior to eating. Their performance, however, went back to normal after consuming food.

When we are hungry, a whole network of brain regions activates. At the center are the ventromedial hypothalamus (VMH) and the lateral hypothalamus. These two regions in the upper brainstem are involved in regulating metabolism, feeding behavior, and digestive functions. There is, however, an upstream gatekeeper, the nucleus arcuatus (ARH) in the hypothalamus. If it registers that the brain itself lacks glucose, this gatekeeper blocks information from the rest of the body. That’s why we resort to carbohydrates as soon as the brain indicates a need for energy, even if the rest of the body is well supplied.

To further understand the relationship between the brain and carbohydrates, we examined 40 subjects over two sessions. In one, we asked study participants to give a 10-minute speech in front of strangers. In the other session they were not required to give a speech. At the end of each session, we measured the concentrations of stress hormones cortisol and adrenaline in participants’ blood. We also provided them with a food buffet for an hour. When the participants gave a speech before the buffet, they were more stressed, and on average consumed an additional 34 grams of carbohydrates, than when they did not give a speech…

In order to meet the increased needs of the brain, one can either eat more of everything, as the stressed subjects did in our experiment, or make it easy for the body and just consume sweet foods. Even babies have a pronounced preference for sweets. Because their brain is extremely large compared with their tiny bodies, babies require a lot of energy. They get that energy via breast milk, which contains a lot of sugar. Over time, our preference for sweets decreases but never completely disappears, even as we become adults. The extent to which that preference is preserved varies from person to person and seems to depend, among other things, on living conditions. Studies suggest people who experience a lot of stress in childhood have a stronger preference for sweets later in life.

For some, the brain cannot get its energy from the body’s reserves, even if there are enough fat deposits. The most important cause of this is chronic stress. To ensure their brains are not undersupplied, these people must always eat enough. Often the only way out of such eating habits is to leave a permanently stressful environment. So although many tend to be hard on themselves for eating too many sweets or carbs, the reasons behind such craving aren’t always due to a lack of self-control and might require a deeper look into lifestyle and stressful situations—past and present. Once the root cause of stress is addressed, eating habits could ultimately resolve themselves.

Achim Peters. Reproduced with permission. Copyright © 2019 Scientific American, a division of Nature America, Inc. All rights reserved.

Quiz

1The desire for sweets and other carbohydrates during stressful times is because they:
2The most important fuel for the brain and body is:
3The brain regions involved in regulating metabolism, feeding behavior, and digestive functions are the:
4The upstream gatekeeper that blocks information from the rest of the body in order to provide the brain with glucose in stressful times is the blank in the hypothalamus.
5Researchers found that participants who gave a 10-minute speech to strangers, later consumed an additional blank grams of carbohydrates compared to when the participants were in a study condition where they did not give a speech.
6Which two stress hormones were measured at the end of each speech session?
Activity Type Title

Chapter 1. Chapter 14

From the pages

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1.1 Quiz

1.

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The desire for sweets and other carbohydrates during stressful times is because they:

A.
B.
C.
D.

2.

_max_tries:1 _feedback_correct: Correct. _feedback_incorrect: Incorrect.

The most important fuel for the brain and body is:

A.
B.
C.
D.

3.

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The brain regions involved in regulating metabolism, feeding behavior, and digestive functions are the:

A.
B.
C.
D.

4.

_max_tries:1 _feedback_correct: Correct. _feedback_incorrect: Incorrect.

The upstream gatekeeper that blocks information from the rest of the body in order to provide the brain with glucose in stressful times is the ____ in the hypothalamus.

A.
B.
C.
D.

5.

_max_tries:1 _feedback_correct: Correct. _feedback_incorrect: Incorrect.

Researchers found that participants who gave a 10-minute speech to strangers, later consumed an additional ____ grams of carbohydrates compared to when the participants were in a study condition where they did not give a speech.

A.
B.
C.
D.

6.

_max_tries:1 _feedback_correct: Correct. _feedback_incorrect: Incorrect.

Which two stress hormones were measured at the end of each speech session?

A.
B.
C.
D.