Metabolism and Mental Health

And why don't more doctors prescribe exercise?

What if all mental disorders are actually metabolic disorders of the brain?

This is the bold argument proposed by Harvard Psychiatrist Christoper Palmer in his book Brain Energy.

His basic theory goes like this:

“Metabolism is how our body creates and uses energy… And we can think of problems with metabolism as energy imbalances”

“Metabolism affects the structure and function of all cells in the body” “Mitochondria are the master regulators of metabolism... When mitochondria aren't working properly, at least some of the cells in your body or brain won't function properly"

“A mental illness is when the brain is not working properly over a period of time, and this causes mental symptoms, which lead to suffering or impairment in functioning”

"Symptoms of mental illness can be understood as overactive, under-active, or absent brain functions”

"Mitochondrial dysfunction or dysregulation can cause all of these through five distinct mechanisms:

(1) cell activity can be overactive (2) cell activity can be underactive (3) some cells can develop abnormally (4) cells can shrink and die (5) cells can have problems maintaining themselves”¹

Dr. Palmer’s conclusion of this argument is that to understand and address any mental illness, we must understand and address the causes of metabolic and mitochondrial dysfunction.

And this pisses off a lot of people.²

A part of this negative reaction is healthy skepticism that something as complex as all mental illnesses could have a single cause. But I think another big part is resistance to the suggestion that our current approach is missing such an essential piece.

Now, I'm not qualified to weigh in on the validity of Dr. Palmer's grand theory. I would not be shocked if there are forms of mental illnesses that do not involve metabolic or mitochondrial dysfunction.

But we don’t need to prove that every form of mental illness has a metabolic cause to find the obvious value in Dr. Palmer’s work.

If metabolism is how our body creates and uses energy. And, effective energy utilization is essential to how the cells in our body (and brain) function. Then surely, nurturing healthy metabolism and cell function is an important contributor to brain function and mental health.

In this context, it’s hard to imagine many people rejecting the statement that a healthy metabolism is an essential part of creating conditions to support mental health.

And yet, there has been so little focus on addressing metabolic health in how we currently treat mental disorders.

Gaps in the Status Quo

Imagine a patient who presents at their primary care doctor with moderate-depression symptoms. The standard of care in most places would be a referral for therapy, a prescription for an SSRI, or both.³

Therapy can be transformative and SSRIs can save lives. Yet, in the context of the importance of metabolic health, there’s clearly a glaring hole in this approach.

Where is the focus on behavioral interventions that might help the patient create a healthy metabolic environment to support their mental health? Why are there no prescriptions or referrals that center on sleep, diet, or exercise? At what point will the patient learn about how stress, inflammation, and hormonal imbalances could be affecting their metabolism and mental health?

I don’t blame individual providers for these gaps. In our existing system, there’s no time for these discussions. Worse, there’s no clear reimbursement for these interventions. In healthcare, patients are typically directed toward interventions that organizations can get paid for.

The reality is that our existing healthcare organizations are simply not well-designed to embrace the complexity of Dr. Palmer’s conclusion.

As he so beautifully highlights, there are numerous causes and potential solutions to mitochondrial dysfunction and poor metabolic health. There are genetic and epigenetic components, chemical and hormonal components, inflammation and circadian components, and diet and exercise components. Dr. Palmer even touches on the potential role of love, adversity, and purpose in life.⁴

Since “all the contributing causes and interventions I have discussed are interrelated and affect each other”, it is challenging to know where to begin. It is also more difficult to implement a single behavioral intervention in isolation.

The Challenge of Prescribing Exercise

Let’s use the example of exercise.

I was surprised by Dr. Palmer’s chapter on physical activity. If metabolic health is so important and exercise improves metabolic health then surely everyone (including people with mental disorders) should benefit from exercise.

Yet, it’s not that simple. Dr. Palmer highlights exercise studies with mixed results. He suggests that people with insulin resistance may see fewer benefits from exercise. Additionally, medications that individuals with mental or chronic illnesses are taking may blunt the positive impact of physical activity.

While he still believes that everyone should exercise, Dr. Palmer introduces the important context that it may be more challenging for or slower to benefit people with metabolic and mental disorders.⁵

This may further explain why doctors are less likely to prescribe exercise and other behavioral interventions. Perhaps they lack conviction that patients will comply with the program or see results quickly enough. They certainly don’t have the right infrastructure to help patients navigate these challenges. So they default to the easier path of prescribing a pill.

New Possibilities on the Horizon

The good news is that exciting work is being done to address these gaps.

My favorite example comes from my wife, a clinical psychologist who studies the impact of exercise on people with severe mental illness. Over the last few years, she has highlighted the benefits of physical activity on people with schizophrenia and begun to design interventions (like walking groups and virtual programs) tailored to support this population. The early results are very promising.

To me, this example points towards a solution.

We need to create interventions, organizations, and incentives that make it as easy for a primary care provider to prescribe exercise (and other behavioral interventions) as it is to prescribe an SSRI.

We need to bridge the gap between fitness and healthcare. We need to shift from treating sickness to nurturing wellness. It’s only by integrating these types of interventions into the scale of the existing healthcare system that we can meet the needs of those who need it most.

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Thank you for reading. If you have any reflections or ideas on this topic, please reach out. I’m working on a few initiatives in this space and always enjoy comparing notes or brainstorming potential solutions.

1. All quotes in this piece come from Brain Energy, By Dr. Christopher Palmer.

2. Many of the critiques I’ve seen of Brain Energy seem to focus on the use of ketogenic diets (which Palmer specifically highlights as only one potential tool) or a lack of a specific actionable solution (which I believe is an intentional choice to honor the complex/personalized nature of the issue). This review by

Awais Aftab

provides a nuanced perspective of the “beef with Brain Energy.”

3. This “standard of care” is based on my experience inside health systems and primary care settings and this New England Journal of Medicine report on "Depression in the Primary Care Setting.

4. I deeply admire and appreciate the level of detail Dr. Palmer provides on each contributing cause and solution. In a world where so many thought leaders are pushing an easy fix, he continually focuses on educating readers on the complexity and interconnection of all these variables.

5. One possible solution to improve the impact of exercise in populations with mental and chronic illnesses is to first focus on other interventions like sleep, diet, and breathwork. This might help reduce stress and inflammation to make the body more capable of handling and benefiting from the additional stress of exercise. Unfortunately, sequencing these interventions in the most impactful way is not something most existing health organizations are currently well suited to do.