The Diary Of A CEO with Steven Bartlett
Most Replayed Moment: Your Food Could Be Making You Depressed! How Diet Impacts Mental Health!
09 Jan 2026
Chapter 1: How does diet influence mental health?
We talk a lot about diet and food on this show. As it relates to metabolism and mental health, diet. So diet is huge. And most people have no clue that diet plays any role in mental illness or mental health. 95% of mental health clinicians think it's laughable that anybody would suggest that diet can play a role in mental illness. They think it's laughable. What do you think?
I think if you do a deep dive into the science, all of the science that we have accumulated over the last 100 years and longer sometimes,
that if you do a deep dive into all of those neuroimaging studies that we've been doing, all of the genetic studies we've been doing, all of the neurotransmitter and hormone studies and trauma studies and adverse childhood experiences studies, if you do a deep dive into the science, And you understand what is happening in the brains and bodies of people as a consequence of those things.
Or what could be causing those things. If you put it all together, you come to this soundbite that mental disorders are metabolic in nature. And there is no reason. questioning whatsoever it is incontrovertible that diet plays a massive huge role in metabolism and therefore i believe very strongly that diet might be playing a role in the mental health epidemic that we are seeing
Chapter 2: What evidence supports the link between diet and mental illness?
And it also might provide an avenue of hope and healing and recovery. And I use the word might as the scientist in me, as the clinician in me. I know without certainty it can heal and recover people who have had chronic, horrible, debilitating mental illnesses. And I know from my own personal story...
When I was in medical school and residency, I'm still suffering from low-grade depression, OCD, other symptoms. But I also developed what's called metabolic syndrome. I developed high blood pressure, high cholesterol, prediabetes. And I wasn't really overweight. I was exercising. I was following a low-fat diet, mostly of processed foods because they're cheaper.
But that was the diet that was touted as a healthy diet. It was low in fat. And as long as it was low in fat, that was supposed to be good for us. And my metabolic syndrome just kept getting worse and worse. And so at some point, in order to treat my metabolic syndrome, I changed my diet to essentially a low-carbohydrate diet. And within three months, my metabolic syndrome was completely gone.
But the thing that just dumbfounded me was that my mental health was better than it had ever been in my entire life. And I just couldn't believe what I was experiencing. I didn't know that I could be that kind of a person. I didn't know that I could be happy and positive and energetic and confident. I had no idea. I didn't think that was in me.
And by changing my diet, all of those things happened.
At the level of the mitochondria, are you saying, do you believe that because you changed your diet to more sort of natural, healthier foods, at the level of the mitochondria, the mitochondria were able to function more naturally themselves and in a more functional way, which meant that the chemicals they release and the processes they go through were more consistent with positive mental health?
Is that like the simpletons way of understanding it? And before then you talked about manmade compounds in the foods, et cetera. I'm assuming you're saying that some of the modern foods that we eat, the ultra processed foods that have all of these random named chemicals inside them that we see on the labels, the mitochondria don't know how to deal with that.
So it's causing the same sort of dysregulation and dysfunction that they might see if we'd gone through like an extreme trauma or something else or some other adverse environmental situation. It's just this dysfunction of the mitochondria, which is causing the knock-on effects we see. But there's many things that can cause dysfunction in the mitochondria.
And we went through a bunch of them earlier. Is that like a simple way of understanding it? 100%. Okay, great. It's perfect. Super interesting. Okay, so on that point then, we have to zoom in on this thing of diet.
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Chapter 3: How can dietary changes impact metabolic disorders?
But we have large epidemiological studies that strongly suggest that people who eat a lot of ultra-processed food have higher... risk for developing depression, anxiety, and other mental disorders. And based on the science, the granular science, based on animal models, so we can do that to mice and rats. And in fact, that's exactly what we see in mice and rats.
We feed them an obesogenic diet, which is usually high in fat, high in carbohydrates, ultra-processed foods. Some researchers have fed rats and mice cafeteria diets where they feed them a lot of delicious junk food. And those mice develop higher rates of obesity, but also higher rates of Diabetes and prediabetes. And oh, by the way, also higher rates of depression and anxiety.
Because those are the two things that we can kind of measure in mice and rats. We can't necessarily measure ADHD symptoms. It's really hard to actually measure psychotic symptoms. But we can measure depression and anxiety symptoms pretty well in animals. And so in animal models, we know that that's unequivocally true.
And we see the same in humans though, because I was reading your book and in chapter four, you say people with ADHD are more likely to develop obesity. People who are obese are 50% more likely to develop bipolar and 25% more likely to develop anxiety or depression. And weight gain around the time of puberty leads to a 400% increase in the chance of depression by the age of 24. Yes.
And insulin resistance at age nine. increases your chances of developing a psychotic at-risk mental state, which is like meaning you're at high risk for developing schizophrenia or bipolar disorder, 500%. And Alzheimer's? All mental disorders are associated with an increased risk of Alzheimer's disease. Anywhere from the lowest is 50% increased risk and the highest is 2,000% increased risk.
And the thread that unites all of these problems is metabolism. Metabolism. And at the end of the day, you have to talk about mitochondria in order to understand metabolism. Only 7% of US citizens have no signs of metabolic health problems. meaning 93% or so of U.S. residents will have at least one of the biomarkers of metabolic syndrome.
meaning they have prediabetes or abnormal lipids or high blood pressure or abdominal obesity or abdominal fat, excessive abdominal fat. So what do we offer those 93%? So those people, diet interventions would absolutely be a part of a healing strategy. A part of it, not the only strategy. I would want to know about their sleep. I would want to know about substance use.
I would want to know about medications, lots of things. But for dietary interventions, I would want to meet them where they're at and just find out, well, where are you at? What are you eating? Do you have preferences or demands for what your diet should be? Could you give me a case study then? Maybe a more extreme case study from your practice that you've seen.
I can give you the simple cases which probably apply to the majority of human beings on the planet. But if it's okay, I'd rather give you the extreme case. Because a lot of people are skeptical. They probably hear me saying this and they think, well, you're just talking about general health and wellness. What about people with real mental illness?
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Chapter 4: What personal experiences shaped the guest's views on diet and mental health?
That I will just share because it's probably one of the most powerful stories I know. It was a woman whose real name was Doris. And in the book, I called her Mildred because I changed everybody's names. But she actually gave me permission to use her real name. So in honor of her, I want to use her real name. So she was a woman who actually had a horrible abuse of childhood, lots of trauma.
And by the time she turned 17, she started having daily hallucinations and delusions and was diagnosed with schizophrenia. Over the ensuing decades, she tried numerous antipsychotic mood stabilizers, antidepressants, and other medicines, but none of them stopped her symptoms. She remained with all of the symptoms of schizophrenia. She ended up gaining a massive amount of weight.
She ended up weighing about 330 pounds by the time she was 75. Her life was devastated by this diagnosis. She had a court-appointed guardian to manage her financial affairs and other affairs.
She had professionals coming into her home to help her with paying bills and grocery shopping and stuff like that because she couldn't do it for herself, which is not at all unusual for people with schizophrenia. And between the ages of 68 and 70, She tried to kill herself at least six times and was hospitalized for those suicide attempts. She hated herself and she hated her life.
When she was 70 years old, her doctor told her, you're overweight and you need to go lose some weight. And she was referred to a weight loss clinic at Duke University where they just so happened to be using the ketogenic diet as a weight loss tool. And for whatever reason, she decided to give it a try. And so she tries the ketogenic diet.
And within two weeks, not only does she start losing weight, but she notices dramatic reduction in her hallucinations and delusions. Within months, all of her symptoms of schizophrenia were in full and complete remission. She starts tapering off her psychiatric meds. Within about six months, she was off all of her psychiatric meds, and her symptoms of schizophrenia remained in remission.
Doris went on to live for another 15 years, symptom-free, medication-free, out of psychiatric hospitals, no more suicide attempts. She stopped seeing mental health professionals pretty quickly because they were kind of worthless in her mind. They hadn't really helped all that much. She lost 150 pounds and kept it off until the day she died. She ended up dying at the age of 85 of COVID pneumonia.
And... But her story tells us like we could get, if you want, we don't have to, we could get into the science of the ketogenic diet and what it's doing to metabolism and mitochondria. I'd love to know. But there's an entire story that helps us understand what happened to her and how exactly that resulted in her really spectacular and almost miraculous recovery.
So unbeknownst to most people, most people know the ketogenic diet is a fad diet. And a lot of people are really worried about it. They've heard that it's dangerous. It'll give you a heart attack. You'll die. Unbeknownst to most people, the ketogenic diet was developed over 100 years ago now by a physician for one and only one purpose. It was developed to stop seizures.
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Chapter 5: What role do mitochondria play in mental health?
But at the end of the day, I'm convinced... that it's really the metabolic changes and the mitochondrial changes that are so important and that are so instrumental in these dramatic improvements and things like stopping seizures or stopping hallucinations and delusions. What about fasting?
There's been a lot of talk, especially recently, about fasting and the impact that that can have on our mental health. Do you think fasting... is a positive for our mental health? So it depends on the person. Okay. And so the ketogenic diet actually mimics the fasting state. That's why it was produced. Oh, right. The ketogenic diet was actually developed by a physician...
recognizing that fasting can have really powerful brain effects, including stopping seizures. If you're out on an island and your friend starts seizing uncontrollably, the best thing to do is to fast them. Even if the seizures stop intermittently, You would think, oh, let's feed you to keep up your sustenance and take care of you.
The best thing to do for your friend, if they are seizing repetitively over days or months, the best thing to do is to fast your friend and to tell them, let's have you go without food for a few days. And that can stop the seizures. The challenge with fasting is that you could starve to death if you do it long enough. That's not a very good treatment for your friend on the island.
And this physician who developed the ketogenic diet recognized that. And so that's why he developed the ketogenic diet, was really looking to see, can we mimic the fasting state with a diet? and get these longer-term benefits. So back to your question, can fasting play a role? 100%, yes, fasting can play a role. And fasting is doing pretty much the same thing that the ketogenic diet is doing.
It's changing mitochondrial biology. It's improving mitochondrial function, changing neurotransmitters, changing the gut microbiome, improving insulin signaling and insulin resistance. It's doing all sorts of beneficial things. There are a couple of caveats with fasting, though. One is that people who are underweight should not fast.
So that includes people with eating disorders who are emaciated or underweight. But it also includes people who have had severe depression and lost weight as a result of their severe depression. Or people with cancer who have lost a significant amount of weight. fasting is not good for them. Fasting mimicking diets like ketogenic diets may in fact be very powerful for those people.
But it needs to be done in a safe, supervised medical way. Sugar. What impact does that have on the mitochondria? If I've got a super high sugar diet, is that impacting my mitochondria in some way and therefore my metabolism? It is. So low intake of sugar in people who are otherwise healthy is perfectly fine and acceptable.
So lots of people can consume treats every now and then or desserts a few times a week or special holiday. They can maybe even binge on sugar over the holidays. And they don't have any problems as a result of it. And that is fine if that's the way it's working out. Again, only 7% of the population is metabolically healthy. So the majority of people, that's not the way it's working out.
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