Mitochondria are at the center of aging, mood and stress
Palmer links mitochondrial function to mental illness, Epel ties chronic stress to mitochondrial damage and Sinclair lists mitochondrial dysfunction as a hallmark of aging. These separate lines of work converge on one target that diet, exercise and stress management all influence.
The Short Version
Three researchers working on very different problems keep arriving at the same small structure inside our cells. Psychiatrist Chris Palmer argues that mitochondria connect metabolism to mental illness, because they help make neurotransmitters, hormones and inflammatory signals, and he believes understanding them lets you "connect all of the dots of the mental illness puzzle." [1] Stress researcher Elissa Epel finds that chronic stress drains mitochondria (caregivers under long-term strain show markedly lower mitochondrial activity) while healthier mitochondria track with better mood [2]. Aging researcher David Sinclair works on the sirtuin, NAD and energy-sensing pathways that fasting and exercise switch on, and Palmer cites a Sinclair paper proposing mitochondrial dysfunction as the unifying link in aging [1][3]. Diet, fasting, exercise and stress practices all act on this shared machinery, which is why the same habits keep showing up in advice about mood, stress and longevity [1][2][3].
Table of contents
What They Said
Chris Palmer: mitochondria as the missing link in mental illness
Chris Palmer, a Harvard psychiatrist, came to mitochondria through his own body [1]. He had mental illness from childhood, OCD first and then depression and suicidality, and during his Harvard residency he developed metabolic syndrome despite a low-fat diet and regular exercise [1]. A switch to the Atkins diet reversed his metabolic syndrome within three months and, unexpectedly, transformed his mood, energy, concentration and sleep [1]. He had always envied people who "work hard and play hard," wondering who had the energy, and says of them: "I assumed that they were just lucky and privileged." [1] The experience made him ask whether metabolism had been part of his own story [1].
As a psychiatrist treating treatment-resistant patients, people who had "already been to six-plus psychiatrists" and "usually tried dozens of different medications," he began offering low-carbohydrate and ketogenic diets [1]. The case that changed his thinking was a 33-year-old man with schizoaffective disorder who had tried 17 medications. On a ketogenic diet, with no change to his medications, he became more engaged within two weeks, and six to eight weeks in his voices were fading and his paranoid beliefs no longer seemed true to him; he has since lost 160 pounds [1].
Palmer's explanation for why a diet could do this runs through the ketogenic diet's long history in epilepsy. Decades of research show the diet influences glutamate, GABA and adenosine, changes calcium channel regulation and gene expression, reduces brain inflammation, changes the gut microbiome and improves insulin signalling [1]. But, he says, "the real magic is that this diet stimulates two processes that relate to mitochondria." [1] The first is mitophagy, "getting rid of old and defective mitochondria and replacing them with new ones." The second is mitochondrial biogenesis: "after people have done the ketogenic diet for a while, months or years, many of their cells in their bodies and brains will have more mitochondria, and those mitochondria will be healthier." [1] "And I believe that is the reason the ketogenic diet is such a powerful treatment, not only for epilepsy, but also for people with chronic mental disorders." [1]
He argues that mitochondria are far more than batteries. People picture them as the cell's power cord, but he sees them as the motherboard, directing and allocating resources throughout the cell [1]. Huberman jokes that science education often treats them as "just sort of like a dumb jock portion of the cell," and Palmer's point is the opposite [1]. Mitochondria help produce, release and regulate serotonin, dopamine, glutamate and acetylcholine, supplying building blocks through the Krebs cycle and energy for synthesis [1]. Research he cites shows mitochondria moving along the synaptic membrane to release batches of neurotransmitter vesicles; when mitochondria were removed and the cell was flooded with ATP, neurotransmitters usually still weren't released [1].
Mitochondria also run hormone production. "We know that mitochondria actually have the enzyme required for the synthesis of steroid hormones. So that includes cortisol, estrogen, testosterone, and progesterone," he says, so "if mitochondria are in short supply or dysfunctional, the production of those hormones may become dysregulated." [1] They shape the stress response: one group that genetically modified mitochondria in four different ways found effects on cortisol, adrenaline and noradrenaline, inflammation and hippocampal gene expression [1]. And "Mitochondria play a direct role in inflammation": a paper in Cell identified mitochondrial reactive oxygen species as "a key signaling process to turn the inflammatory process off," and other work shows mitochondria signalling macrophages between phases of wound healing [1].
Neurotransmitters, hormones, gene expression and inflammation are all disrupted in mental disorders, and "our field has struggled to understand, but how do they fit together?" [1] His answer: "I believe once you understand the science of mitochondria, you can actually connect all of the dots of the mental illness puzzle." [1]
Palmer explicitly links this to aging. He notes that "it has long been known for decades that mitochondrial dysfunction is associated with everything that ails us, essentially," and cites a paper by David Sinclair proposing that "mitochondria are actually the unifying link of everything that we know about aging." [1] In Palmer's paraphrase of that idea: "Defective mitochondria or defective mitochondrial function, mitochondrial dysfunction, is possibly the unifying cause of aging and all of the aging-related disorders." [1] Mitophagy, he says, is the body's way of addressing it, and the most powerful tool we have to stimulate it is diet: calorie restriction is "the oldest, truest, best proven way to prevent aging in a wide variety of animal species," alongside fasting, intermittent fasting and fasting-mimicking diets [1].
He also cautions against the phrase itself. Some researchers want to move away from "mitochondrial dysfunction" because mitochondria specialize: "not all mitochondria can produce cortisol," only those in cells such as the adrenal gland [1].
Elissa Epel: chronic stress wears down mitochondria
Elissa Epel of UCSF directs the Center on Aging, Metabolism and Emotions and has spent her career studying how stress gets under the skin, including its effects on mitochondria and telomeres [2]. Her starting point is energy. The stress response is energetically expensive, drawing on ATP made by mitochondria, which helps explain why chronic vigilance leaves people exhausted [2]. Mounting a stress response and recovering is healthy; the modern problem is keeping it alive long after the event, largely through our thoughts [2].
With Martin Picard, she measured mitochondrial health in blood [2]. Mothers caring for children with autism had markedly lower mitochondrial activity than mothers of neurotypical children [2]. Across caregivers, those with healthier mitochondria reported more positive emotion, especially in the evening, and that same-day link was stronger than the link with mood on other days [2]. Evening mood matters in its own right: people who can find some contentment, ease or joy at the end of a stressful day tend to have less depression, heart disease and early death a decade later [2]. So in Epel's data, mitochondria sit where stress, mood and long-term health meet.
Her other markers point the same way. When her team pinged caregivers in the evening, how much they were wishing things were different and how engaged they were in the present predicted unhappiness and shorter telomeres [2]. Toxic, chronic stress accelerates aging; a threat response brings constricted blood vessels, rising cortisol, slow recovery and inflammation, while a challenge response brings more blood flow, more oxygen to the brain, lower inflammation afterward and longer telomeres [2]. Chronic stress also pushes metabolism: it drives cravings for high-fat, high-sugar comfort foods, often with higher insulin or insulin resistance, and deposits fat in the abdomen [2].
Epel also looks for ways to reverse the damage. Short-term meditation training dampens inflammatory gene expression and boosts telomerase, and long-term meditators have longer telomeres [2]. Her newest work tests positive stress. In a study with Wendy Mendes and Aric Prather, participants practiced daily for three weeks, randomly assigned to low-arousal methods (mindfulness, slow breathing) or high-arousal positive stress (aerobic exercise or the Wim Hof method) [2]. "The level of stress anxiety and depression fell dramatically in everyone," and "the Wim Hof method did create daily positive emotion that increased over time." [2] The next step is biological: "we're going to look at mitochondrial enzymes telomere and gene expression patterns," she says, because "we don't really think that telomers can change very quickly." [2] She describes the goal as "releasing the inherent power of rejuvenation that's in our body," and insists "we just can't reduce inflammation with a drug we can't reduce stress with a drug." [2]
David Sinclair: the energy-sensing machinery of aging
David Sinclair, a Harvard geneticist, frames aging differently from Palmer. His main theory is that aging is a loss of information in the epigenome, which he likens to scratches on a CD that make cells play the wrong genes [3]. On the hallmarks of aging, which the field agreed on in the 2000s and arranged "on a pizza, so everyone got an equal weighting," he says his epigenetic loss is "the main driver of aging. And these other hallmarks are largely manifestations of that process." [3] So Sinclair would likely see mitochondrial decline as downstream of information loss rather than the root cause, even though Palmer cites a Sinclair paper naming mitochondrial dysfunction as a possible unifying cause [1][3].
Still, much of Sinclair's practical work runs through the cell's energy sensors. His lab showed in 2005 that low levels of insulin and insulin-like growth factor switch on the sirtuins, seven longevity genes, while constant feeding keeps them off [3]. Sirtuins need fuel: NAD, a molecule that declines with age, obesity and never being hungry, partly because an enzyme called CD38 breaks it down [3]. Sinclair takes a gram of NMN every morning to raise NAD, and says in mice NMN let old animals run 50% further while NR did not [3]. He takes it in the morning because NAD follows a circadian rhythm [3].
Fasting raises sirtuin activity and lowers mTOR, which senses amino acids, and together that turns on the body's defenses: clearing old proteins, improving insulin sensitivity and repairing cells [3]. Longer fasts of two or three days trigger a deeper cleanup, chaperone-mediated autophagy [3]. He takes metformin, a diabetes drug that mimics low energy, but skips it on exercise days [3]. He says its effect on muscle growth is overstated, though it may reduce stamina a little [3].
Sinclair gives mitochondria a specific role in his warning about antioxidants. Once seen as the key to longevity, antioxidants largely failed in animals and humans [3]. "There's even what's called myto-hormesis, which is your mitochondria power packs need to have a little bit of these free radicals to be able to function," he says, "so you don't want to overdose on these antioxidants." [3] His approach is to turn on the body's defenses rather than mop up free radicals [3].
He also lifts weights to maintain muscle and hormones, and says his InsideTracker-estimated age dropped from 58 to 31 in months once he got serious again [3]. He sleeps cool as part of a metabolic winter hypothesis, eats mostly plants, and skips a meal a day [3].
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Where They Agree, and Where They Don't
Agreement
Energy metabolism is not a side issue. Palmer treats mitochondria as the organizing principle of mental illness [1], Epel measures them as a readout of chronic stress and mood [2], and Sinclair's longevity pathways (sirtuins, NAD, mTOR) sense the cell's energy and nutrient state [3]. All three see the cell's energy economy as upstream of health, not just a consequence of it.
Eating less, or less often, is a shared lever. Palmer calls calorie restriction the best-proven way to prevent aging across animal species and says fasting and fasting-mimicking diets stimulate mitophagy [1]. Sinclair skips a meal daily and uses longer fasts to trigger deeper autophagy [3]. Epel, from the stress side, targets the sugar-heavy eating that chronic stress drives, arguing that removing sugary drinks and addressing cravings matters for metabolism [2].
Inflammation is part of the same story. Palmer says mitochondria help turn inflammation on and off [1]. Epel links threat responses to inflammation and shows meditation dampening inflammatory gene expression [2]. Sinclair tracks high-sensitivity CRP as the best marker of cardiovascular inflammation [3].
Drugs alone are not the answer. Palmer uses diet alongside, not instead of, medication, and warns that coming off medication is "very difficult and dangerous" without supervision [1]. Epel says we cannot reduce inflammation or stress with a drug [2]. Sinclair uses supplements and metformin but builds his routine around fasting, exercise and plants [3].
Disagreement and tension
Root cause or downstream effect? This is the main difference. Palmer believes mitochondria are the unifying thread for mental illness and cites Sinclair's paper to extend that to aging [1]. Sinclair, in his own conversation, names epigenetic information loss as the main driver of aging and calls the other hallmarks "largely manifestations of that process." [3] Epel mostly treats mitochondria as a marker that reflects stress and predicts mood, without claiming they are the cause [2]. The fair conclusion is that all three see mitochondria as central, but only Palmer places them at the very root.
How much the evidence proves. Palmer is candid: "If you're looking for randomized controlled trials, documenting efficacy in large numbers of patients with these disorders, we don't have them." [1] Epel's mitochondria findings in caregivers are associations, and her Wim Hof study had not yet analyzed its mitochondrial enzymes [2]. Many of Sinclair's findings are in mice, and he says he shares what he does rather than making recommendations [3].
Is "mitochondrial dysfunction" even the right idea? Palmer notes some researchers want to drop the term because mitochondria specialize by cell and task [1]. Sinclair adds that mitochondria actually need some free radicals to function, which makes the idea that less oxidative stress is always better a mistake [3].
Carbohydrates versus timing. Palmer's most powerful intervention is carbohydrate restriction down to ketosis [1]. Sinclair says "it's not as important what you eat. It's when you eat during the day." [3] Both approaches lower insulin and both stimulate cellular cleanup, which may be why they converge, but they emphasize different levers.
Why It Works
One organelle, many jobs
Palmer's list explains why a single target could affect mood, stress and aging together. Mitochondria supply the building blocks and energy for neurotransmitters and physically help release them at synapses [1]. They contain the enzyme for making cortisol, estrogen, testosterone and progesterone [1]. They regulate the stress response and hippocampal gene expression [1]. They send signals that turn inflammation off and steer wound healing [1]. When they falter, all these systems can go wrong at once, which is exactly the scattered picture psychiatry sees in mental disorders [1].
Stress spends mitochondrial energy
Epel's mechanism is that stress is costly. Every stress response draws on ATP made by mitochondria, so a response that never switches off keeps drawing down the cell's energy [2]. Long-term caregivers, living with a stressor that cannot be removed, show that toll in lower mitochondrial activity [2]. The link runs both ways in her data: healthier mitochondria go with more positive emotion the same day [2].
Fasting and diet renew mitochondria
Palmer describes mitophagy as a specialized form of autophagy, the body's recycling of old parts through lysosomes; it runs at a low level all the time but fasting, calorie restriction and fasting-mimicking diets strongly stimulate it, and the body targets old and defective parts first [1]. The ketogenic diet mimics fasting long term, which is why it was developed for epilepsy, and adds mitochondrial biogenesis [1]. In epilepsy the results were large: early on, 50% of patients became seizure-free and another 35% had at least a 50% reduction; in drug-resistant patients about a third became seizure-free, a third improved by half or more and a third saw no benefit [1].
Sinclair's version of the same logic: low insulin switches on sirtuins, low amino acids turn down mTOR, and together they turn on defenses including clearing old proteins and repairing cells [3]. Sirtuins depend on NAD, which declines with age and with never being hungry [3].
A little stress helps; constant stress harms
Sinclair's mitohormesis point, that mitochondria need a small amount of free radicals to function, parallels Epel's finding that short bursts of positive stress such as aerobic exercise or Wim Hof breathing reduce stress and anxiety [2][3]. Both suggest mitochondria respond well to brief challenges and poorly to either constant overload or total protection.
Where It Applies, and Where It Doesn't
Serious mental illness needs supervision. Palmer's ketogenic approach aims for blood ketones above roughly 0.8 millimolar for depression and above 1.5 for psychotic and bipolar disorders, and he insists people with serious illness work with a professional because medications may need adjusting [1]. "Weight loss, everybody wings it," he says, but serious disorders need "a real shot at this diet" with medical help [1].
For everyday burnout, the bar is lower. For adults not on psychiatric medication, Palmer suggests trying carbohydrate restriction for a while; one vegetarian reader with chronic anxiety cut some high-carb foods and within three weeks said, "I can't believe how much better I feel." [1] For some patients just "getting rid of junk food can make a huge difference in a mood disorder." [1]
Stress you cannot remove needs different tools. Epel's caregivers cannot fast or exercise their way out of their situation; her tools for them are radical acceptance, dropping the rope on what cannot change, and finding ease in the evening [2].
Exercise alone may not be enough. Palmer was exercising regularly and eating low-fat when his metabolic syndrome kept worsening; the diet change is what reversed it [1].
The unified picture is a hypothesis. Mitochondria as the shared root of mental illness and aging is Palmer's reading, supported by a paper he attributes to Sinclair; Sinclair himself emphasizes the epigenome, and Epel's data are associations [1][2][3]. The habits the three recommend overlap, but the single-cause story is not settled.
Anyone with a psychiatric diagnosis, diabetes or on medication should talk with their doctor before starting a ketogenic diet, extended fasting or supplements such as metformin or NMN.
What To Do With It
- Cut junk food first. Remove highly processed, shelf-stable foods, especially the high-sugar, high-fat combination Palmer calls "the worst combination for metabolic health." [1]
- Try carbohydrate restriction if you feel burned out. If you are not on psychiatric medication, cut high-carb foods for a few weeks and watch mood and energy, as Palmer suggests [1].
- Leave space between meals. Skip one meal a day, building up in stages rather than going cold turkey, to lower insulin and switch on sirtuins [3].
- Treat longer fasts and ketosis as stronger tools. Two-day fasts and ketogenic diets trigger deeper cellular cleanup and mitochondrial renewal, but reserve them for when you are healthy or supervised [1][3].
- Use short positive stressors. Aerobic exercise, strength training and breathwork such as the Wim Hof method each reduced stress, anxiety and depression in Epel's study, and Sinclair lifts to keep muscle [2][3].
- Don't megadose antioxidants. Sinclair says mitochondria need a little oxidative signalling, so avoid overdosing vitamins such as C and A [3].
- Stop chronic stress from running all day. Notice how much time you spend wishing things were different, drop the rope on what you cannot change, and practice meditation, which Epel links to lower inflammatory gene expression and higher telomerase [2].
- Protect your evenings. Look for some ease or contentment at the end of each day; in Epel's research, evening mood tracks mitochondrial health and predicts long-term outcomes [2].
- Never stop psychiatric medication on your own. Work with a prescriber if you want to use diet as a treatment [1].