Why Some People Handle Stress Worse Than Others, Even When They Look Healthy

Most of us think of stress as something we simply “feel.” A fast approaching deadline, financial hardship, relationship problems, or the endless stream of breaking news and notifications can leave us feeling overwhelmed and stressed out.

But what if stress changes the way your body responds to everyday life, even before any symptoms of disease appear?

A study from researchers at UCLA’s Oppenheimer Center for Neurobiology of Stress and Resilience sheds light on this question. The findings suggest that people living with high levels of ongoing stress may interpret everyday situations more negatively, show altered nervous system responses, and differences in metabolites linked to the gut microbiome.

Surprisingly, the highly stressed participants were not sick. They were healthy young adults. However, their bodies were already showing signs that chronic stress may be reshaping the way they perceive and respond to the world.

Stress Changes More Than Your Mood

The researchers compared two groups of healthy women. One group reported high levels of ongoing stress and anxiety, while the other reported low levels. The investigators then exposed both groups to a series of tests designed to measure emotional responses, cognitive performance, autonomic nervous system activity, and blood metabolites.

As expected, the high-stress group experienced a larger increase in negative emotions during a stressful mental arithmetic task. The high-stress participants also interpreted neutral images more negatively than the low-stress group. In other words, when presented with emotionally vague information, they were more likely to view it through a negative lens.

This finding supports an idea that chronic stress may create a “negativity bias,” making the brain more likely to perceive uncertainty as threatening. If we extrapolate this to everyday life, a delayed text message or a minor disagreement with a loved one could be interpreted more negatively than intended. Over time, this can create a cycle that increases emotional distress and further amplifies stress responses.

I can personally relate to this tendency. Negative thinking patterns have affected several members of my family, and I have struggled with them myself at different points in my life. Learning to recognize and interrupt these patterns has been an important part of my own healing journey and I’ll share some of the strategies that helped me later in this article.

What Does the Gut Have to Do With It?

As readers of the Mind-Gut Connection newsletter know, stress never affects the brain alone. One of the most interesting aspects of this study was the measurement of blood metabolites associated with the gut microbiome and host metabolism.

The researchers observed significant differences between the high-stress and low-stress groups in metabolites related to tryptophan metabolism. Tryptophan is an essential amino acid that serves as a precursor for serotonin and other compounds involved in mood regulation and immune function.

Previous animal and human studies have shown that chronic stress can alter the composition and activity of the gut microbiome. These stress-induced microbial changes can result indirectly from stress-related changes in gut transit, secretions, and stress hormones which can create a different habitat for the gut microbiome. But a direct modulation of microbial gene expression in response to the stress mediator norepinephrine has also been reported.

This study cannot prove that microbiome changes caused the differences observed in stressed individuals. However, the findings add to the evidence that chronic stress influences the complex communication network linking the brain, gut, immune system, and microbiome. Stress is not simply a psychological experience. It is a whole-body biological process.

Why This Matters & How to Adapt Your Response to Stress

One of the most important takeaways from this study is that stress-related changes can occur long before someone develops a noticeable illness.

Let’s recall that the participants in this study were healthy. They did not have psychiatric disorders or significant medical conditions. Yet measurable differences were already present in their emotional processing, autonomic nervous system activity, and metabolic profiles.

By the time conditions such as anxiety disorders, depression, chronic pain syndromes, irritable bowel syndrome, or inflammatory bowel disease emerge, these stress-related changes may have been developing for a long time.

Research continues to show that regular physical activity, mindfulness practices, adequate sleep, social connection, time in nature, and a diet rich in plant-based foods can help improve resilience and support the health of the brain-gut-microbiome system.

My own healing journey began after my diagnosis of ulcerative colitis. My initial tools were gut-directed hypnotherapy and partaking in a mindfulness stress reduction group. These practices helped me become more aware of my habitual thought patterns, reduce my reactivity to stress, and develop a healthier relationship with the challenges I was facing.

While everyone’s journey is different, this study serves as a reminder that effectively managing stress is not simply about feeling better today. It may also be one of the most important investments we can make in our long-term physical and emotional health.