Among the global rise in obesity rates, a study showed that being overweight can lead to mental health issues like anxiety and also impair brain functioning. The animal study suggested that the two conditions may be connected through interactions between the gut and the brain.
Conducted in mice, the research linked diet-induced obesity with anxiety-like symptoms, alterations in brain signaling, and differences in gut microbes that may contribute to impaired brain functioning.
"Our findings suggest that obesity can lead to anxiety-like behaviour, possibly due to changes in both brain function and gut health," said Desiree Wanders, Associate Professor and chair of nutrition at Georgia State University, US.
In addition to other risks of obesity such as type 2 diabetes and heart disease, the study focussed on its potential impacts on brain health using a mouse model that develops many of the same obesity-related issues seen in humans.
The team subjected six-week mice to a low-fat diet (16) and a high-fat diet (16) for 21 weeks.As predicted, the mice on a high-fat diet weighed significantly more and had significantly more body fat than those fed a low-fat diet.
In behavioural tests, the researchers found that the obese mice displayed more anxiety-like behaviours, such as freezing (defensive behaviour mice exhibit in response to a perceived threat), compared with lean mice.
These mice also showed different signalling patterns in the hypothalamus a region of the brain involved in regulating metabolism, which could contribute to cognitive impairments.In addition, the researchers observed distinct differences in the makeup of gut bacteria in obese mice compared with lean mice.
"These findings could have important implications for both public health and personal decisions," said Wanders. "The study highlights the potential impact of obesity on mental health, particularly in terms of anxiety.
By understanding the connections between diet, brain health, and gut microbiota, this research may help guide public health initiatives that focus on obesity prevention and early intervention, particularly in children and adolescents."
The findings will be presented at the ongoing NUTRITION 2025, the flagship annual meeting of the American Society for Nutrition in Orlando, Florida.