How does stress cause our brains to crave comfort foods?

  • According to a new study, eating comfort foods when under stress turns off the region of the brain that keeps you from overeating.
  • Under normal circumstances, this region neutralizes the chemical reward one gets from eating, making it less enjoyable.
  • The phenomenon takes on its full meaning in wild animals, including non-modern humans, favoring a rapid supply of energy in response to a threat.
  • However, it is less useful in today’s world, where stress is less often directly related to survival.

For those under stress, it might seem like comfort foods offer the ideal — and perhaps the only — quick fix. A new study in mice from the Garvan Institute of Medical Research in Sydney, Australia, however, suggests that these people should think twice before feasting.

The study reveals that the combination of stress and comfort foods disables the brain’s mechanism for knowing when enough has been eaten.

This can lead to overindulgence in comfort foods of choice, as well as weight gain and obesity, potential sources of even more stress.

The brain area affected is the lateral habenula, an organ that exists in both mice and humans. Under normal conditions, the region produces a mild, unpleasant sensation in the short-term presence of a high-fat diet, turning off the brain’s reward response, thus making continued eating less pleasant. Many comfort foods are high in fat.

Working with chronically stressed mice, the researchers found that the lateral habenula remained unusually quiet when high-fat foods were eaten. The mice continued to eat, apparently for pleasure, without being satisfied.

Upon further analysis, the researchers found that after giving the stressed mice a sugar-free, calorie-free food pellet, they consumed twice as much of the sugar pellet (or liquid) as the unstressed mice. This demonstrates that a preference for sweets – even without calories – persisted in stressed mice.

Confirming their finding, when the researchers reactivated the lateral habenula using an optogenetic light capable of controlling neuronal activity, the mice stopped overeating.

The study is published in neuron.

It’s not entirely clear if there’s a universal definition of comfort food, said Dr. A. Janet Tomiyamawho did not participate in the study.

“People assume that comfort foods are automatically foods that are high in fat, sugar, and calories,” she said, “but no one has systematically tested that.”

The general sense, however, says Dr Lesley Rennis, who also was not involved in the study, is that “comfort foods are foods that taste good and make us feel good. Typically, it’s calorie-dense, high in sugar and fat, and often has nostalgic and sentimental value.

“Sometimes called hyper-appetizing foods, these foods are rewarding and stimulate the release of feel-good hormones like serotonin.”
— Dr. Lesley Rennis

Much research has investigated the psychological appeal of comfort foods. Dr. Rennis said the study adds to the conversation.

“It provides a layer of insight into the physiology of stress and its impact on food intake. Like all disease states, there are physiological and psychological factors that contribute to dietary stress,” she said.

Asked about the likelihood of a mouse study producing results that would also apply to humans, the study’s lead author, Dr. Chi Kin Ipand Dr. Tomiyama felt it was.

“Humans are animals just like mice, and studies in non-human animals provide very tight experimental control that provides valuable information that we simply cannot get in humans,” Dr. Tomiyama said.

Dr. Ip explained some of the similarities between humans and animals:

“The anatomical structure as well as the function of the habenula is highly conserved across all species, including humans.”

“The lateral habenula is a region that plays an essential role in the regulation of emotional response. Under activation, it triggers aversive behavior, which is one of the mechanisms that trigger emotional distress. However, when reduced to silence it induces the opposite, which is a reward response,” he said.

He further noted that a molecule identified in the study as being important for the behavior of the lateral habenula is also present in humans.

If eating comfort foods in response to stress can lead to weight gain, can this be a sensible personal strategy?

From an evolutionary perspective, according to Dr. Ip, yes it is possible.

“Foraging behavior is probably the most critical behavior that is conserved in any species to support survival,” he said.

Dr Ip said animals living in the wild are not privileged to indulge in high fat food sources and their stress systems allow them to survive by adjusting their energy intake and supply accordingly. current demands.

High fat foods offer a way to gain energy quickly, and as Dr. Ip said, “Having more energy in the body is certainly better in nature than having less energy. “.

In modern humans, stress is less relevant to our literal survival.

Responding to concerns about weight gain due to stressful eating, Dr Rennis said: “Indulging in comfort food once in a while is fine.”

On the other hand, Dr. Tomiyama explained, “We know that there is a huge stigma attached to higher weight in this country, and I’ve spent a decade of research showing that weight stigma is stressful and drives a biological response to stress.

Dr. Rennis noted that overeating comfort foods in response to stress is “similar to occasional alcohol consumption for relaxation. It’s fine once in a while, but it can lead to problems if done in excess.

Dr. Tomiyama pointed out that comfort foods don’t have to be high in sugar, fat, or calories to be comforting.

“We have a study where we trained people to feel better after eating fruit,” she said.

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