Mental Disorders and Biological Instability: When the Brain Is No Longer an Isolated Organ

by Laurent Glatz – for Athletic Carnivore

The brain does not float above the body. It consumes a massive amount of energy, depends on a constant metabolic supply, and reacts to stress hormones, glucose fluctuations, inflammation, sleep, the microbiome, deficiencies, and immune signals. When the body becomes unstable, the psyche can become unstable alongside it.

This principle does not mean that all psychiatric illnesses are “caused” by diet, nor that a diet can cure everything. It means something more precise: in many mental disorders, there is a vulnerability of the nervous system to measurable biological disturbances. Bipolar disorder, ADHD, anxiety disorders, depression, obsessive-compulsive disorders, eating disorders, sleep disorders, chronic irritability, brain fog, impulsivity, hypersensitivity, extreme fluctuations in energy or mood—all these conditions can be worsened by an unstable biological terrain.

Separating the Mental from the Metabolic Is Artificial

The dominant belief still too often separates the mental from the metabolic. On one side, the brain, emotions, psychiatric diagnoses. On the other, sugar, insulin, liver, hormones, inflammation, gut. This separation is artificial.

A blood sugar that rises and falls can alter mood, concentration, aggression, anxiety, and compulsions. Elevated cortisol for too long can disrupt sleep, increase vigilance, weaken memory, amplify rumination, and reduce nervous system recovery capacity. Chronically high insulin can indicate a metabolic resistance that also affects the brain. Disrupted leptin can disturb satiety, energy, and eating behaviors. Unstable ghrelin can intensify emotional hunger, urgent eating, and the search for stimulation.

What the patient calls “I don’t feel well” can sometimes be the subjective translation of a biological system sending contradictory signals.

The Common Thread: Loss of Regulation

In bipolar disorders, stability is central: stability of sleep, energy, mood, circadian rhythm, neuronal excitability. In ADHD, regulation is also key: attention, impulsivity, motivation, dopamine, frustration tolerance, need for stimulation.

In autism, one should not reduce the individual to a disease to be “corrected,” as it is a particular neurodevelopmental profile; yet associated vulnerabilities often exist: hypersensitivity, digestive issues, anxiety, unstable sleep, selective eating, sensory overload, inflammation, or individual intolerances.

In depression, modern models no longer limit themselves to a simple “serotonin deficiency”: mitochondrial energy, inflammation, insulin resistance, the stress axis, sleep, and brain metabolism are involved. In all these cases, the common factor is not a single cause. The common factor is a loss of regulation.

Why a Carnivore or Low-Carb Approach Can Stabilize the Terrain

This is where the carnivore or very low-carb diet can become a coherent intervention hypothesis: it aims to reduce biological oscillations. Fewer carbohydrates generally mean fewer blood sugar fluctuations and lower insulin spikes. More animal proteins and natural fats often mean more stable satiety, a diet richer in essential nutrients, reduced ultra-processed foods, and less exposure to hyperpalatable combinations that stimulate compulsion.

For some people, adapting to fats and ketone bodies can provide the brain with a steadier fuel than the glucose-crash-glucose cycle. The sought-after benefit is not just weight loss. It is stability: more predictable mood, less aggressive hunger, more linear energy, more regular sleep, clearer concentration, reduced irritability, better stress resilience.

But this approach must be precisely formulated: it can improve the terrain, reduce certain triggers, diminish some symptoms, and sometimes profoundly transform a person’s condition. It does not claim to systematically “cure” bipolar disorder, ADHD, autism spectrum disorder, or diagnosed psychiatric illnesses.

The Real Question

The real question is not: “Does the carnivore diet cure all mental illnesses?” The real question is more serious: how many mental disorders are worsened by a brain fueled in an unstable metabolic environment?

If an individual lives with glucose spikes, fragmented sleep, chronic inflammation, food compulsions, unpredictable energy, disturbed digestion, and an overloaded stress axis, can we truly assess their mental state without first stabilizing their biological terrain?

The carnivore diet, when properly managed, aims precisely at this foundation: simplifying signals, reducing fluctuations, restoring a form of internal coherence. It does not replace medical supervision, especially in severe disorders or under treatment. But it raises a question that modern medicine too often avoids: what if part of mental instability comes from a body that no longer has the biological conditions necessary to produce a stable brain?