Stress and Obesity Could Be Linked, Study Suggests

Stress may be the reason people with obesity are more likely to get other metabolic diseases, such as type 2 diabetes, according to a recent study.

Scientists at Rutgers University, New Jersey, experimented on genetically engineered mice to investigate how overeating leads to insulin resistance, otherwise known as prediabetes.

“Stress and obesity, in essence, work through the same basic mechanism in causing diabetes, through the actions of stress hormones,” said the study’s senior author, Christoph Buettner from Rutgers Robert Wood Johnson Medical School, in a statement.

Prediabetes affects more than a third of the U.S. population, according to the Centers for Disease Control and Prevention (CDC), and can develop into type 2 diabetes, which affects approximately one in 10 Americans.

Individuals with diabetes struggle to process sugars from food with the hormone insulin. Thursday, November 14 is World Diabetes Day.

Obesity is a key risk factor for type 2 diabetes—the most common form of diabetes—but up until now, scientists thought this was because excess weight disrupted insulin signals in liver and fat cells.

“We have been interested in the basic mechanisms of how obesity induces diabetes,” said Buettner. “Given that the cost of the diabetes epidemic in the U.S. alone exceeds $300 billion per year, this is a critically important question.”

It was already known that stress hormones could impair insulin from doing its job—transporting sugars from the blood to be used elsewhere in the body as fuel—and result in higher levels of sugar in the blood.

But the Rutgers scientists tested the importance of this relationship by feeding high-fat, high-sugar diets to mice.

They found that mice on the diet had elevated levels of the stress hormone norepinephrine within days, indicating how quickly eating too much food can activate the body’s stress response.

Then the scientists tested the effects of the overfeeding diet on mice who were genetically engineered not to produce stress hormones outside their brains and central nervous systems.

These mice ate as many calories and got just as obese as the normal mice, but they didn’t develop insulin resistance.

“We were delighted to see that our mice ate as much because it indicates that the differences in insulin sensitivity and their lack of metabolic disease are not due to reduced food intake or reduced obesity but due to the greatly reduced stress hormones,” said Buettner.

“These mice cannot increase stress hormones that counteract insulin; hence, insulin resistance does not develop during obesity development.”

The scientists concluded that stress hormones might be the fundamental mechanism behind insulin resistance in people with obesity.

“Many types of stress—financial stress, marital stress, the stress associated with living in dangerous areas or suffering discrimination, or even the physical stress that comes from excessive alcohol consumption—all increase diabetes and synergize with the metabolic stress of obesity,” said Buettner.

This study was only on mice, but Buettner and his colleague, first author of the study Kenichi Sakamoto, are planning to conduct human studies to confirm their findings.

If these studies produce similar results, they may lead to new approaches to tackling insulin resistance and diabetes, focused on reducing stress hormones rather than targeting insulin directly.

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Reference

Sakamoto, K., Butera, M. A., Zhou, C., Maurizi, G., Chen, B., Ling, L., Shawkat, A., Patlolla, L., Thakker, K., Calle, V., Morgan, D. A., Rahmouni, K., Schwartz, G. J., Tahiri, A., Buettner, C. (2024). Overnutrition causes insulin resistance and metabolic disorder through increased sympathetic nervous system activity, Cell Metabolism. https://doi.org/10.1016/j.cmet.2024.09.012