It’s no secret that humanity at large is in the throes of a mental health crisis. Rates of depression, anxiety, and other mental health disorders have climbed steadily and dramatically over the past several decades, and although younger people and those in wealthy nations are disproportionately affected, this is no doubt a global problem. The Global Burden of Disease Study identifies mental health disorders as the leading cause of disability worldwide.
Mental Health issues include both diagnosed major mental health disorders (schizophrenia, bipolar disorder, major depression, and anxiety) and what many people would describe as common struggles, including low mood, generalized anxiety, lack of motivation, brain fog, and an overarching sense that something feels off.
At the same time as humanity is experiencing this tsunami of chronic disease, we have more access to treatment than ever before. Public awareness around mental health has improved significantly, going to therapy is more widely accepted, and in the U.S. alone, over 240 million prescriptions are written each year for antidepressant medications.
Both psychotherapy and pharmacology can be incredibly valuable and, in many cases, life-saving. And yet, for many people under treatment, outcomes are still not where they want them to be. This raises an important question: If we are doing more than ever before, why are so many people still struggling?
We tend to think of mental health as something separate from physical health, as if it exists in isolation somewhere in a nebulous realm of “emotional well-being.” If you are struggling mentally, the assumption is that the solution must be mental as well.
But that picture is incomplete.
The way you think, feel, and experience the world comes from within your physiology. The brain is an organ in the body, like any other. It is part of a complex system that depends on energy supply, nutrient availability, hormone signaling, sleep cycles, movement patterns, and environmental inputs. A paper in the Journal of the American Medical Association found that there was significant overlap of “poor body health” with all four major mental health disorders — schizophrenia, bipolar disorder, depression, and anxiety. When the body is deconditioned, under- or overnourished, underslept, or full of inflammation, so is the brain. Mental health is physical health.
On the other hand, viewing mental health disorders purely as an imbalance of chemicals in the brain is clearly not the complete picture either. Plenty of pharmaceutical medications have been developed that manipulate brain chemistry (and hundreds of millions of prescriptions have been written, as noted above), and yet many people are still suffering. A major analysis looked at data on 17.47 million patients diagnosed with depression that had long-term follow-up (nine years). Just over half took antidepressant medication, and the other half did not. Based on eight quality-of-life measurements, it was concluded that there was no significant improvement in quality of life for those taking the antidepressants.
We need more tools to help people improve their quality of life. Throughout this article, we will explore insights from the current scientific literature that add to the repertoire of interventions available to those who are struggling. This conversation is not “either/or.” We are not pitting the standard of care and lifestyle factors against each other, nor are we arguing for abandoning traditional interventions. Anything and everything that works is on the table.
Similarly, if someone breaks their leg, we do not debate whether they should receive medical treatment or eat well and rest to support healing. We do both. We stabilize the injury, and we support the body’s ability to recover.
Mental health deserves the same approach.
Metabolic and Mental Health
In simplest terms, metabolism is the sum of all the chemical processes that keep us alive, including turning food into energy and using that energy to build, repair, and maintain the body. The hormone insulin, as a key driver of pushing fuel (glucose) into cells, is a major player in this complex system. Many aspects of modern life are ruining insulin’s ability to do its job properly — a condition called insulin resistance. A frightening statistic: only 6.8% of U.S. adults have optimal metabolic health, meaning 93.2% have standard biomarkers of metabolic dysfunction.
There is a growing body of evidence linking metabolic dysfunction to mental health outcomes, particularly depression. For example, individuals with insulin resistance have significantly higher rates of depression, leading researchers to hypothesize that an impaired ability to regulate glucose levels in the blood may affect brain function and mood regulation. In a Dutch prospective cohort study of adults aged 18 to 65 with no lifetime history of depression or anxiety, markers of insulin resistance independently predicted (in a statistical model) the development of future depression. Over nine years of follow-up, participants with poorer metabolic health had a 200% to 300% greater risk of developing depression.
Research also shows chronic low-grade inflammation, which commonly accompanies metabolic dysfunction, can alter neurotransmitter signaling and contribute to depressive symptoms by disrupting normal brain chemistry. What’s not clear is whether inflammation causes mental health disorders, if mental health disorders cause inflammation, or both. In a study on twins, those with metabolic dysfunction were more likely to have depression, and having markers of inflammation was also significantly associated with depression and signs of neurodegeneration (damaged neurons in the brain).
Additional reviews in the emerging field of metabolic psychiatry have proposed that depression in some individuals may be, in part, a disorder of energy metabolism in the brain rather than purely a disorder of thoughts, emotions, or neurotransmitter chemicals. Dr. Chris Palmer, a psychiatrist at Harvard, spoke at length about this field of research at the CrossFit for Health conference in 2024.
The takeaway is straightforward. When the body’s ability to produce and deliver energy is compromised, the brain is affected, showing symptoms like depression, anxiety, mental fatigue, mood instability, low motivation, and impaired mental clarity.
Research Insight No. 1: Metabolic Health Influences Mental Health
Diet and Mental Health
What exactly is the source of all this metabolic dysfunction so forcefully impacting human health within the last 50-100 years? Sleep deprivation, stress, and lack of exercise all play a role, but research suggests that diets high in refined carbohydrates and ultra-processed foods are a significant contributing factor.
With industrial ultra-processed foods overtaking society and displacing real, whole foods, diets in all parts of the world are increasingly at odds with the needs of our physiology. We are getting far too much of certain elements (sugar, refined carbs, industrial oils, additives, preservatives) and far too little of others (fiber, high-quality protein, vitamins, and minerals).
In terms of brain health, neurotransmitters such as serotonin and dopamine are built directly from nutrients obtained from the diet. Every bit of you is built out of something you ate, after all. The chemicals that drive brain function are no different.
Large-scale observational data have also shown that individuals consuming diets higher in ultra-processed foods have significantly higher rates of depression compared to those consuming more whole, minimally processed foods
Drilling down into the “why” behind this “what,” one controlled study demonstrated that reduced availability of tryptophan (an amino acid found in protein that is the precursor to serotonin) led to measurable worsening of depressive symptoms. Serotonin is a neurotransmitter chemical known for influencing emotional stability and a sense of calm. It also affects appetite, gut motility, pain perception, learning, and memory. When we don’t have enough of the building blocks, we can’t construct the chemicals we need to achieve a balanced mental state.
In one randomized controlled trial, adults with major depression who improved diet quality by replacing processed foods such as refined carbs, fried foods, and processed meats with whole foods such as meat, eggs, fish, vegetables, fruit, whole grains, and legumes experienced significantly greater improvements in depressive symptoms than a control group receiving social support alone.
Thirty-two percent of participants in the dietary group achieved scores that met the study’s defined criteria for clinical remission (a MADRS score of <10) of depression, compared to just 8% in the control group. The paper concludes:
“These results indicate that dietary improvement may provide an efficacious and accessible treatment strategy for the management of this highly prevalent mental disorder, the benefits of which could extend to the management of common co-morbidities.”
Translation: Not only could improving the diet improve mental health, but it could also improve other common health problems, too.
Taken together, these findings reinforce a simple idea: the food you eat is not just fuel, it is raw material for brain function. A diet centered around meat, vegetables, nuts and seeds, some fruit, little starch, and no sugar is an important cornerstone of health.
Research Insight No. 2: Diet Shapes Brain Function
Sleep and Mental Health
Sleep plays a central role in emotional regulation and mental well-being, and yet at least one in three adults in the U.S. is not getting enough of it (seven hours or less each night), according to the CDC.
That’s a significant problem because sleep deprivation literally changes the way the brain functions.
In one landmark study, researchers found that just a single night of sleep deprivation increased amygdala reactivity (the part of the brain responsible for detecting emotional threats) by roughly 60%, while weakening its connection to the prefrontal cortex (the region responsible for emotional regulation and rational decision-making). In practical terms, sleep deprivation makes people more emotionally reactive and volatile while reducing their ability to regulate those emotions, making everyday stressors feel more intense and more difficult to handle.
Over the long term, the relationship between sleep and mental health becomes even more significant. Chronic sleep disturbance is strongly associated with increased risk of developing depression, and the relationship appears to be bidirectional. Poor mental health can disrupt sleep, but poor sleep can also contribute to the development and worsening of mental health symptoms. In a meta-analysis of longitudinal studies, individuals with insomnia were found to have roughly double the risk of developing depression compared to those without insomnia.
Focusing on the positive, this situation can be improved! Research clearly shows that improving sleep directly improves mental health. A meta-analysis of 65 randomized controlled trials involving more than 8,600 participants found that interventions that improved sleep quality also produced meaningful improvements in depression, anxiety, stress, and rumination. Even more compelling, the researchers found a dose-response relationship, meaning the greater the improvement in sleep quality, the greater the improvement in mental health outcomes.
Taken together, the evidence suggests that sleep should not be an afterthought in a healthy lifestyle. It is an active pillar of mental health, and when sleep quality deteriorates, mental health often follows.
Research Insight No. 3: Sleep is brain maintenance
Exercise and Mental Health
If sleep is one of the most overlooked pillars of mental health, movement may be one of the most underprescribed.
The relationship between exercise and mental health has been recognized for decades, but the strength of the evidence has grown substantially in recent years. What was once seen as a helpful lifestyle habit is now increasingly understood as a legitimate therapeutic tool in both the prevention and treatment of depression.
On the prevention side, the data are striking. A large systematic review and meta-analysis published in 2022 found that people who engaged in higher levels of physical activity had a significantly lower risk of developing depression compared to those who were least active. The researchers estimated that if inactive adults met basic physical activity recommendations (~150 minutes/week of brisk walking, for example), approximately 11.5% of cases of depression could be prevented.
Exercise also plays a significant role once depression is already present. A large network meta-analysis published in the British Medical Journal examined hundreds of randomized controlled trials and found that walking, jogging, yoga, strength training, and mixed-mode exercise all produced significant improvements in depressive symptoms. The improvements were “proportional to the intensity prescribed,” meaning higher-intensity exercise produced better results, with some improvements rivaling psychotherapy and medication in effectiveness. A separate meta-analysis published in the British Journal of Sports Medicine reinforced this finding, showing that exercise interventions consistently reduced symptoms of depression across diverse populations, with higher-intensity exercise often producing larger effects.
A Cochrane Review published just this year on exercise for depression analyzed randomized controlled trials and concluded that exercise produces meaningful reductions in depressive symptoms, with effects comparable to established treatments. Some study participants even had improvements in their symptoms that exceeded standard treatments. You may have seen splashy headlines in the news heralding “Exercise is as effective as medication in treating depression, study finds” or “Scientists find exercise rivals therapy for depression.”
These findings are worth sitting with for a moment. Depression is often framed as something that happens to us, as though it arrives independently of the way we live. While certainly not the only factor, physical inactivity appears to be one of the modifiable risk factors that can influence whether depression develops in the first place.
Taken together, the evidence raises an interesting question: Is exercise a treatment for depression, or is movement so fundamental to human physiology that the absence of it creates deficiency symptoms, one of which may be disturbed mental health?
That question is significant because it changes the frame and the way we approach helping people.
If movement is medicine, then exercise becomes one treatment option among many. But if movement is a biological requirement, like sleep or nutrition, then physical inactivity begins to look less like a neutral state and more like a form of deconditioning, with predictable downstream effects on both body and mind.
This is where CrossFit offers something unique. CrossFit is not simply about burning calories or improving aesthetics. It restores one of the most fundamental inputs human physiology expects: regular, varied, high-intensity movement. And in doing so, it may be addressing not only physical health, but some of the biological foundations of mental health as well.
Research Insight No. 4: Movement is foundational to mental health
Expanding the Therapy Model
CrossFit is constantly varied, functional movement, executed at high intensity. Our methodology emphasizes appropriate scaling to achieve high intensity within the individual’s physical and psychological tolerances. Our structured coaching environment and varied programming no doubt improve physical tolerance, but how often do we really think about the ‘psychological tolerance’ aspect of our training?
The CrossFit affiliate is a lab of sorts, where individuals are repeatedly exposed to physical and psychological challenges, allowing for real-time observation of how thoughts, emotions, and behaviors respond under stress. Concepts such as resilience, self-awareness, and failure as a training tool are drawn directly from real experiences within the affiliate.
What opportunity do we have to bridge the gap between exercise and the traditional therapeutic approach?
Traditional therapy has largely been built around a seated model: a patient on a couch or chair, talking through thoughts, emotions, and experiences with a trained professional. This can be incredibly valuable, but it is worth asking whether talking while sitting still is the only or even the best way to process difficult internal experiences.
Emerging research suggests that movement can be intentionally integrated into the therapeutic process. In one pilot study on “walking psychotherapy,” therapists and patients conducted sessions while walking outdoors rather than sitting indoors, and both patients and practitioners reported that the movement and the natural environment enhanced emotional openness, engagement, and the therapeutic process. More recently, a clinical trial comparing walk-and-talk therapy to conventional seated therapy in men with low mood found comparable improvements in depressive symptoms, while also improving stress regulation and overall engagement with treatment.
This idea makes intuitive sense. Human beings did not evolve to process life’s challenges while seated in climate-controlled offices under fluorescent lights. For most of human history, difficult thoughts, problem-solving, and emotional processing happened while moving through the world, walking, working, hunting, carrying, and navigating the unknown and unknowable.
In my recent discussion on the CrossFit Podcast with Bill Anthes, licensed therapist and founder of the Ruck Race League, he discussed rucking as more than just exercise. A long walk under load, without music, distractions, or the constant stimulation of modern life, creates a rare opportunity for internal exploration. The body is occupied, the mind is free, and difficult thoughts often surface.
As a former affiliate owner and Seminar Staff member, Anthes also knows that our physically challenging workouts can also be accompanied by intense emotions bubbling to the surface. Rather than deflect or suppress these emotions, he recommends integrating the experience in real time through a readily accessible practice like journaling.
This does not mean every workout is therapy, but it does suggest that movement can be more than exercise. When paired with reflection, journaling, conversation, or intentional quiet, physical training can become a powerful tool for both psychological processing and physical adaptation.
Human beings are also inherently social creatures, and social isolation exacts a measurable toll on our health. The U.S. Surgeon General issued a report on the Epidemic of Loneliness and Isolation. Sadly, one in 12 adults reports having no close friends at all, and 53% report having only one to four friends. Research consistently shows that loneliness and social disconnection are associated with higher rates of depression and poorer long-term health outcomes, while stronger social ties improve stress resilience and are associated with longer life expectancy. In other words, connection is part of the human operating system.
Exercise can be one of the most practical ways to build that connection. Whether it’s a CrossFit class, a walking group, or a ruck with friends, physical activity creates shared experiences that naturally strengthen social bonds. There is something uniquely powerful about voluntarily taking on discomfort alongside other people. Shared challenge requires us to be vulnerable, which builds trust and creates a sense of belonging that is difficult to manufacture through casual socializing alone. In that sense, group exercise does more than improve physical health. It creates community, and community itself may be one of the most underappreciated tools we have for protecting mental health
Research Insight No. 5: Therapy can include multiple modalities
Own Your Health
Mental health is influenced by a wide range of factors, including nutrition, sleep, exercise, environment, life experiences, social connections, and even genetics. At the same time, there are meaningful lifestyle factors that individuals can control to take agency over their own well-being. Standard pharmaceutical treatments can be effective, but they are often accompanied by negative side effects and questionable long-term outcomes.
Lifestyle interventions such as exercise, nutrition, sleep, and social connection influence many of the same biological systems and often provide broader side benefits beyond mental health.
This does not suggest replacing one with the other. It highlights the value of integrating multiple approaches. Understanding the connection between physiology and psychology expands the available toolkit. And for many people, recognizing that is where meaningful change begins.
Learn More
Former Green Beret, longtime CrossFit coach, and licensed therapist Bill Anthes joins Jocelyn Rylee for a conversation that cuts straight to the heart of what it means to train the whole human. Drawing from military selection, years on Seminar Staff, clinical practice, psychedelic integration work, and the creation of the Ruck Race League, Bill explores the deep connection between physical stress, psychological patterns, and nervous-system awareness.
He and Jocelyn dig into failure as a training tool, why monotonous work exposes truth, how coaches can hold space without overreaching, and what it means to listen to the body instead of overriding it.