Study Reveals Permanent Brain Changes due to Obesity – Diminished Nutrient Response Found by Yale Researchers

by Liam O'Connor
7 comments
Obesity-linked Brain Changes

Yale researchers have discovered an association between obesity and a reduced brain response to nutrient consumption, a response that persists even after weight loss. This study sheds light on why maintaining weight loss proves difficult for some individuals and underscores the pivotal role of the brain in obesity.

The new study reveals that obesity results in a lessened brain response to nutrient intake, and this diminished response fails to return even after weight loss.

The ingestion of food prompts the gut to send a sequence of signals to the brain indicating the presence of nutrients, which scientists theorize could help regulate eating habits. However, Mireille Serlie’s new research at Yale suggests that while nutrient detection triggers changes in brain activity in lean individuals, this response is significantly weakened in those with obesity.

These disparities in brain activity, according to the researchers, might provide insight into why losing weight and maintaining weight loss is a challenge for many.

The study was published in Nature Metabolism on June 12.

According to the World Health Organization, over 4 million individuals worldwide die annually due to being overweight. Researchers emphasize the importance of understanding the biological factors contributing to obesity to mitigate its widespread, destructive effects. Although the body’s response to nutrient intake could be a crucial aspect of eating behavior, the role of nutrient signaling in humans remains poorly understood.

In the study, the researchers administered glucose or fat directly into the stomachs of 28 lean individuals (with a body mass index, or BMI, of 25 or less) and 30 individuals with obesity (BMI of 30 or more). They subsequently monitored brain activity using functional magnetic resonance imaging (fMRI).

Among lean participants, the infusion of both glucose and fat led to a decrease in activity across various brain regions. Conversely, no activity changes were noticed in participants with obesity.

This lack of change in brain activity among obese individuals was unexpected, said Serlie, professor of medicine (endocrinology) at Yale School of Medicine and the study’s senior author.

The team then focused on the striatum, a brain region known to mediate the rewarding and motivational aspects of food intake and to play a crucial role in eating behavior regulation, primarily through the neurotransmitter dopamine.

Utilizing fMRI, they discovered that both glucose and fat resulted in decreased activity in two parts of the striatum in lean participants. However, in obese participants, only glucose led to changes in brain activity, and that too, only in one area of the striatum. Fat had no effect on brain activity in this region. The researchers also noted that glucose induced dopamine release in all participants, while fat caused dopamine release only in lean participants. These observations, the researchers suggested, align with reduced nutrient sensing in individuals with obesity.

Obese participants in the study underwent a 12-week dietary weight loss program. Those who lost at least 10% of their body weight were re-imaged. The researchers found no alteration in the brain’s response to nutrient infusion even after weight loss in these individuals.

Previous studies have noted that most people regain weight within a few years of dieting. This new study may provide insights into why this pattern is so prevalent.

The study also emphasizes that understanding the biological underpinnings of human eating behavior is still in its nascent stages. More research is required to identify why reduced nutrient sensing occurs in certain individuals, the biological pathways involved, and the onset of these changes.

Despite occasional overeating being common, it remains unclear why some people persistently overeat while others do not. Uncovering the point when the brain begins to lose its ability to regulate food intake, and what triggers this change could pave the way for preventive measures.

Knowing when nutrient-sensing changes become irreversible could help doctors determine treatment strategies for patients. Serlie envisions that a future objective might be to find a way to restore nutrient sensing, if feasible.

Regardless, these findings underscore the pivotal role of the human brain in obesity.

There’s a persistent notion that obesity stems from a lack of willpower. However, Serlie said, their study reveals tangible differences in nutrient sensing in the brain, challenging this belief.

The reference to the study is: “Brain responses to nutrients are severely impaired and not reversed by weight loss in humans with obesity: a randomized crossover study” by Katy A. van Galen, Anouk Schrantee, Kasper W. ter Horst, Susanne E. la Fleur, Jan Booij, R. Todd Constable, Gary J. Schwartz, Ralph J. DiLeone, and Mireille J. Serlie, published on 12 June 2023, Nature Metabolism. DOI: 10.1038/s42255-023-00816-9.

Frequently Asked Questions (FAQs) about Obesity-linked Brain Changes

What were the findings of the Yale study on obesity and brain function?

The study discovered that obesity is linked to a diminished brain response to nutrient intake. Surprisingly, this response does not recover even after weight loss, potentially explaining why maintaining weight loss is often difficult.

Who led the study at Yale?

The study was led by Mireille Serlie, a professor of medicine (endocrinology) at Yale School of Medicine.

How was the research conducted?

Researchers administered glucose or fat directly into the stomachs of a group of lean individuals and a group with obesity. They then monitored changes in brain activity using functional magnetic resonance imaging (fMRI).

What did the researchers discover about the role of the striatum in obesity?

They found that in people with obesity, the striatum – a brain region known to regulate eating behavior – showed decreased activity when glucose was administered, but not when fat was administered. This contrasted with lean individuals, where both glucose and fat decreased striatum activity.

What implications do these findings have for treatment of obesity?

The study underscores the significant role of the brain in obesity and suggests that understanding when nutrient-sensing changes become irreversible could help physicians determine treatment strategies. One future objective might be to find a way to restore nutrient sensing.

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7 comments

Mariah H June 13, 2023 - 2:28 pm

Seriously? Brains change due to obesity?? Didn’t know that. so it’s not just about eat less and move more, huh?

Reply
Samuel_1984 June 13, 2023 - 7:40 pm

I used to think obesity is all about lack of will power. This article really changed my perspective.

Reply
Keith_P June 13, 2023 - 9:56 pm

who woulda thought the brain had such a big part to play in obesity. The mind is a powerful thing, isn’t it?

Reply
Linda Perkins June 14, 2023 - 12:16 am

I’d never thought about the brain’s role in obesity before this, it’s a real eye opener.

Reply
Jenny87 June 14, 2023 - 2:31 am

There’s hope then, maybe scientists can find a way to restore nutrient sensing, that’ll be a game changer!

Reply
TommyS June 14, 2023 - 5:35 am

Hard to believe, but guess science never lies. Scary stuff, but good to know.

Reply
John Stevenson June 14, 2023 - 9:47 am

wow, its kinda scary how obesity can affect the brain so much. Will definitely think twice before overindulging.

Reply

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