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High-fat diets and mental health: How your gut influences anxiety

high-fat diet

High-fat diets, such as the typical Western diet, have long been associated with obesity and mental health disorders like anxiety. Recent research sheds light on how these diets may disrupt the gut microbiome and gut-brain signaling, contributing to anxiety.

The link between obesity, high-fat diets, and anxiety

Individuals with obesity are more likely to experience anxiety and other mental health disorders. High-fat diets have been identified as a possible contributor to both obesity and anxiety, altering the gut microbiome’s composition. The gut microbiome may influence obesity-related metabolic factors and affect anxiety-like behavior through the microbiota-gut-brain axis.

New study insights

A recent study investigated the effects of a high-fat diet over nine weeks on rats, analyzing shifts in the gut microbiome, microbiome-gut-brain axis, and serotonergic systems in the brain. The results suggest that high-fat diet-induced obesity may disrupt gut bacteria and their signaling pathways to the brain, impacting brain chemicals associated with anxiety.

Key findings

  • Rats fed a high-fat diet gained more weight and body fat.
  • These rats had significantly lower gut microbiome diversity, linked to poorer health.
  • Increased expression of genes related to serotonin production and signaling was observed in the brainstem’s dorsal raphe nucleus, an area linked to stress and anxiety.

The findings suggest that high-fat diets alter gut microbiome composition in ways associated with increased body fat and weight and changes in brain serotonin systems related to anxiety.

Expert opinions

Dr. Thomas M. Holland from the RUSH Institute for Healthy Aging noted that high-fat diets reduce gut microbiome diversity, impairing the gut’s ability to maintain a balanced environment. Timothy Frie, a nutritional neuroscientist, explained that the microbiome-gut-serotonergic brain axis represents a critical communication pathway between the gut microbiota and the brain, particularly focusing on serotonin, essential for mood regulation.

Dietary recommendations

Experts recommend supporting the gut microbiome and signaling pathways through healthy eating and reducing the intake of high-fat and overly processed foods. Dr. Holland suggests increasing the intake of:

  • Omega-3-rich foods: fatty fish, flaxseeds, chia seeds, hemp seeds, and walnuts
  • Fermented foods: yogurt with live cultures, kefir, sauerkraut, kimchi, miso, and tempeh
  • Prebiotic foods: garlic, onions, leeks, asparagus, bananas, and oats
  • Dark leafy greens: spinach, kale, Swiss chard, arugula, and collard greens
  • Berries: blueberries, strawberries, raspberries, and blackberries

Frie similarly advises consuming a diet rich in omega-3s, fermented foods, and fiber from fruits, vegetables, and whole grains to promote the growth of beneficial gut bacteria, enhancing microbial diversity and gut health.


Understanding the microbiome-gut-brain axis opens new avenues for therapeutic interventions targeting the gut microbiome to modulate brain function and improve mental health outcomes. By improving dietary habits, individuals can support better gut-brain signaling, reduce inflammation, and enhance overall mental health.