Diet-induced obesity linked to anxiety and cognitive impairment in mice

Key Takeaways:

• Obesity in mice was linked to increased anxiety-like behaviours, altered brain signalling, and gut microbiome changes, suggesting a complex interaction between diet, brain function, and gut health.
• Findings reinforce the growing evidence of a gut–brain axis in mental health, highlighting that obesity may contribute directly to cognitive and emotional challenges.
• While conducted in mice, the study supports the value of multi-system approaches to obesity research, prevention, and intervention, particularly during adolescence.

Introduction: Rising Rates, Unanswered Questions

As obesity and anxiety both continue to rise—especially among younger populations—researchers are increasingly investigating whether these conditions are biologically connected. A new preclinical study led by Dr Desiree Wanders, Associate Professor and Chair of Nutrition at Georgia State University, suggests a potential causal link, identifying diet-induced obesity in mice as a driver of anxiety-like behaviours, disrupted brain function, and gut microbiome imbalances.

The findings will be presented at NUTRITION 2025, the annual flagship meeting of the American Society for Nutrition, held from 31 May to 3 June in Orlando, Florida.

Study Design: A Closer Look at the Brain–Gut–Diet Connection

To explore the neurocognitive impact of obesity, researchers developed a mouse model designed to mirror human obesity-related health outcomes. The study involved 32 male mice, observed from six to 21 weeks of age—equivalent to adolescence through early adulthood in humans.

During this time:

• Half of the mice were fed a low-fat diet, while
• The other half received a high-fat diet known to induce obesity.

By the end of the study period, the high-fat group exhibited:

• Significantly greater body weight, and
• Higher levels of body fat than their low-fat-fed counterparts.

Behavioural and Neurological Outcomes

Behavioural tests revealed that mice with obesity displayed more anxiety-like behaviours. Notably, they exhibited increased “freezing” responses—a defensive behaviour in rodents when perceiving threats. This behavioural profile was not seen in the lean control group.

Neurological analysis revealed changes in signalling within the hypothalamus, a brain region that plays a central role in:

• Regulating metabolism,
• Hormonal control, and
• Emotional behaviour.

Such alterations may help explain the cognitive impairments often reported in people living with obesity.

“Several studies have pointed to a link between obesity and anxiety, though it is still unclear whether obesity directly causes anxiety or if the association is influenced by societal pressures. Our findings suggest that obesity can lead to anxiety-like behaviour, possibly due to changes in both brain function and gut health.”
— Desiree Wanders, PhD

Microbiome Findings: Distinct Gut Profiles in Mice with Obesity

Beyond brain signalling, the study also explored the gut microbiota—microorganisms that reside in the gastrointestinal tract and are known to influence both digestion and brain health. In mice with obesity, the researchers observed marked differences in gut microbial composition compared to the lean group.

This supports a growing body of research into the gut–brain axis, suggesting that:

• The microbiome may regulate not only digestion but also emotional and cognitive function.
• Obesity-related changes in gut bacteria may be part of a chain reaction affecting brain health.

Implications for Public and Personal Health

Although animal models cannot replicate the full complexity of human biology and environment, Wanders emphasised the relevance of these results for human health strategies.

“These findings could have important implications for both public health and personal decisions. The study highlights the potential impact of obesity on mental health, particularly in terms of anxiety.”
— Desiree Wanders, PhD

The research adds weight to the argument that obesity’s consequences extend beyond metabolic disease and cardiovascular risk, reinforcing the importance of:

• Preventive strategies, particularly in childhood and adolescence;
• Early interventions, and
• Comprehensive health policies that address mental as well as physical health.

Contextual Considerations and Future Research

Wanders also cautioned against overly simplistic interpretations of the data:

“While our findings suggest that diet plays a significant role in both physical and mental health, it is important to remember that diet is just one piece of the puzzle,” she said. “Environmental factors, genetics, lifestyle choices and socioeconomic status also contribute to the risk of obesity and its associated health outcomes.”

Looking ahead, Wanders and her team plan to:

• Investigate the mechanisms through which diet-induced obesity alters the brain,
• Conduct parallel studies including female mice and different age groups, and
• Explore whether weight loss interventions might reverse or mitigate the observed changes in behaviour, brain function, and gut health.

Presentation Details

Dr Wanders will present the full research findings during the Obesity session at the Orange County Convention Center on Sunday, 1 June, from 11:45 a.m. to 12:45 p.m. EDT.