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Eating a low-carbohydrate, whole-foods diet appears to be a powerful strategy for improving a number of health conditions. Could this same nutritional strategy benefit the brain as well? Emerging science and clinical experience suggest that the answer could be yes.

Disclaimer: Low-carb nutrition and psychiatric diseases is a unique field without much research or experience. Therefore, although this guide passed our review for being labeled evidence-based, we acknowledge that much of the evidence is low quality or even anecdotal experience. In fields where there is sparse scientific research, we need to rely on clinical experience from experts in the field. We hope to be able to update this guide in the future as more research becomes available.

Many people think of mental health problems like depression, anxiety, and ADHD as chemical imbalances that require medication, but how often do we stop to wonder what causes these chemical imbalances? While medications are clearly helpful and important for some individuals, one could argue that the most powerful way to change brain chemistry is through food — because brain chemicals can be influenced by nutrients in the food we eat.

This logical idea has given birth to the new and exciting field of nutritional psychiatry, dedicated to understanding how dietary choices affect our mood, thinking, and behavior. Emerging science and real-world experiences are revealing this empowering and hopeful new message: feeding your brain properly has the potential to prevent and reverse symptoms of mental health disorders, and in some cases help people reduce or even eliminate the need for psychiatric medications.

The steep rise in mental health problems around the world in recent decades closely parallels the pattern of many other so-called “diseases of civilization” associated with the industrialization of the human diet. Although many public health messages blame animal protein and fat for our predicament, meat is not a risky new foreign substance; it is an ancient, nutritious whole food that has been available since time immemorial.

While we can’t know precisely how much meat prehistoric peoples around the world used to eat, we do know that no human being could have survived without animal foods. Plant foods lack certain nutrients essential to human life, most notably vitamin B12, and B12 supplements were not available prior to the 1950s.

What best distinguishes today’s so-called “Western” diet from every dietary pattern that has ever come before it is not the presence of meat but the abundance of refined carbohydrates like sugar and flour, along with refined seed oils (aka “vegetable oils”) like soybean and sunflower oil. These two substances, which are found in most of the processed and prepared food on the market, are the true signature ingredients of modern diets.

Although the science isn’t entirely settled, refined carbohydrates and seed oils may potentially contribute to inflammation, oxidation, hormonal imbalance, and insulin resistance — all of which research suggests may be key drivers of many physical and mental health problems.

To be clear, these are not the only forces at play, and poor dietary quality is not the only factor influencing our risk for psychiatric disorders. However, since there is evidence connecting food choices with disease-producing processes, improving the quality of our diet makes good sense.

Low-carbohydrate diets and psychiatric disorders

Anxiety disorders

Anxiety disorders include generalized anxiety disorder (excessive worry), panic disorder, post-traumatic stress disorder, obsessive-compulsive disorder, and social phobia. While there aren’t any formal published studies yet, there are numerous anecdotal reports and examples within my practice of people achieving significant relief from anxiety on LCHF and ketogenic diets. In my clinical experience, anxiety reduction is one of the most common benefits of LCHF diets.

A 31-year-old Mexican-American Harvard post-doctoral student came to me requesting help with frequent panic attacks, irritability, constant food cravings, “emotional eating,” and sleepiness occurring two hours after meals. She was very health-conscious and hoped to avoid medication. I told her that her symptoms were probably related to carbohydrate sensitivity and recommended a whole foods LCHF diet. She changed her diet from this:

Breakfast: Toast with peanut butter or Nutella, coffee with skim milk

Toast with peanut butter or Nutella, coffee with skim milk Lunch: Salad with tuna or cheese and a piece of bread

Salad with tuna or cheese and a piece of bread Dinner: Pasta with cheese

Pasta with cheese Snacks: Bananas and yogurt

to this:

Breakfast : Two eggs with butter and guacamole

: Two eggs with butter and guacamole Lunch: Meat and non-starchy vegetable

Meat and non-starchy vegetable Dinner: Meat and non-starchy vegetable

Meat and non-starchy vegetable Snacks: Nuts and cheese

When asked how the new diet had affected her symptoms, she told me: “I don’t know how I dealt with it because they all used to bother me A LOT, but I would say that the symptoms are 90% gone.”

Depression

Medicines which reduce inflammation and improve insulin resistance can effectively treat depression symptoms, suggesting that inflammation and insulin resistance may play an important role in the development or severity of depressive disorders.

In 2017, the world’s first study of dietary intervention for clinical depression found that a Mediterranean-style diet eased depression symptoms to a modest degree as compared to the typical modern diet, and a second study of a similar diet supplemented with fish oil noted benefits as well.

These important studies clearly demonstrate that dietary quality matters to mental health. But they can’t tell us whether a Mediterranean diet is the best diet for the brain, only that it’s better than the standard modern diet. While it is tempting to believe that these diets reduced depression symptoms because they are higher in foods like olive oil and nuts, they were also designed to be very low in refined carbohydrates and seed oils. Researchers are now beginning to consider how sugar consumption can contribute to the risk of depression. More studies are needed to explore how and why different diets may affect depression symptoms.

There are no published human trials yet on low-carbohydrate diets and depression, but there are numerous instances within my own practice and many shared anecdotes of people reporting improved mood, including these two social media reports, shared with permission:

Bipolar disorders

Bipolar disorders used to be called “manic-depression.” They come in many forms, including bipolar type 1, bipolar type 2, and some common milder forms that don’t fit neatly into either category. All of these disorders are characterized by unstable mood patterns that include periods of increased intensity (“highs”) such as mania, irritability, or severe anxiety, usually alternating with periods of depression. Interestingly, bipolar disorders and epilepsy have a lot in common, including similar neurotransmitter imbalances and electrolyte disturbances.

In fact, since some of the same medications are used to treat both disorders, it’s logical to wonder whether ketogenic diets, which have been used to treat epilepsy for nearly a century, could be helpful in managing bipolar disorder as well.

A study of 121 people with bipolar mood disorders found that those who also have insulin resistance or type 2 diabetes face a harder road than those who don’t. Those with insulin resistance or type 2 diabetes were more likely to have chronic and rapidly-cycling mood symptoms and were less likely to respond to the mood-stabilizing medication lithium.

In a published case study, two women with bipolar 2 disorder reported that a ketogenic diet was superior to the anticonvulsant/mood stabilizer lamotrigine (Lamictal) for managing their mood symptoms and that they were able to stop taking medication.

In an example from my own practice, a 26-year-old woman with bipolar 2 disorder who had struggled with bulimia and frequent migraines for many years adopted an LCHF diet and experienced complete resolution of binge-purge behaviors, migraines, and premenstrual distress. In addition, her “highs” shifted from angry to happy and her “lows” became less intense. We managed the leftover depression symptoms with a low dose of lamotrigine (a mood-stabilizing antidepressant medication) and psychotherapy.





Psychosis

Psychotic symptoms don’t just occur in people with schizophrenia. They can also occur in many other psychiatric conditions, including depression, bipolar disorder, substance use disorders, and dementia.

Signs of psychosis include paranoia, auditory hallucinations (hearing voices), visual hallucinations (seeing things that aren’t there), intrusive thoughts/images, and/or disorganized thinking. Interestingly, people diagnosed with schizophrenia may be more likely to have glucose regulation problems and insulin resistance, even if they’ve never taken antipsychotic medications known to increase risk for these issues.

We don’t have enough information yet to know whether insulin resistance may play a causal role in schizophrenia, only that the two conditions often go hand in hand.

Several published case reports have documented that low-carbohydrate diets sometimes appear to dramatically improve symptoms of psychosis.

Perhaps the most remarkable and best-documented case, published by Dr. Eric Westman and Dr. Bryan Kraft, tells the story of a 70-year old woman who had suffered with auditory and visual hallucinations since age seven. Within only eight days of switching to a low-carbohydrate diet, her symptoms noticeably improved. She remained free of hallucinations while eating this way even a full year later.

You can read more details about some of these cases in this article: “Ketogenic diets for psychiatric disorders: a new 2017 review.”

Note that it’s not possible to know how common these experiences of improvement are, or what exactly they are caused by.

Autistic spectrum disorder (ASD)

Two small six-month studies and one case report have demonstrated that a ketogenic diet may be helpful for symptoms of autistic spectrum disorders in children. In one of the studies, of the 23 children who stuck with the diet, 18 children (60%) experienced some degree of benefit, with two children improving enough to advance to mainstream schools.

Attention deficit/hyperactivity disorder (ADHD)

While there are studies suggesting that simplified low-allergen diets consisting primarily of whole foods can be very helpful in children with ADHD, there are no studies yet that explore the relationship between refined carbohydrates and ADHD. Nor are there any that test low-carbohydrate diets on children or adults with ADHD. However, in my clinical experience, improved mental clarity is one of the most commonly reported benefits of low-carbohydrate diets, and I have seen cases of even severe ADHD that have responded to dietary intervention, such as this one:

Several years ago, I met with a 40-year-old woman who’d had lifelong symptoms of procrastination, lateness, poor motivation, low energy, distractibility, and disorganization that interfered significantly with her effectiveness at work and at home. I diagnosed her with ADHD, inattentive type, and she was started on Adderall (mixed amphetamine salts). Adderall greatly improved her symptoms but brought uneven benefits throughout the day and some annoying side effects. Over the past couple of years, she gradually improved the quality of her diet by removing grains, legumes, dairy, and most processed foods, which helped her mood and improved her physical health tremendously, but did nothing for the ADHD symptoms. When she decided to shift to a ketogenic diet several months ago, her symptoms began improving within just a few days. She has since stopped Adderall entirely and reports that she functions even better when in ketosis than on Adderall, without any side effects.





Alzheimer’s disease

Research exploring the connection between metabolism and most psychiatric disorders is in its infancy, but when it comes to Alzheimer’s disease, we have multiple lines of evidence demonstrating that insulin resistance of the brain is not only a core feature of Alzheimer’s disease but is likely to be a primary driving force in the development of this devastating illness. The relationship between insulin resistance and Alzheimer’s is so strong that many scientists now refer to Alzheimer’s as “type 3 diabetes.”

One of the ways insulin resistance contributes to poor brain function in Alzheimer’s disease is by restricting insulin’s entry into the brain. Since insulin is required for brain cells to use glucose effectively, low brain insulin may cause sluggish brain glucose processing and slowing of brain cell activity. This drop in brain power can begin decades before any cognitive symptoms become obvious and has been detected in women as young as 24 years old. So it’s never too early to begin reducing your risk.

It’s also almost never too late. A small but growing number of studies demonstrate that mildly ketogenic diets and/or ketone supplements modestly improve thinking and memory in some people with “mild cognitive impairment” (pre-Alzheimer’s). In the 2018 study described here, the LCHF diet plus MCT oil supplements (which raise blood ketone levels) improved cognitive test scores in people with mild Alzheimer’s disease a little better than any existing Alzheimer’s medication.

This dietary strategy was safe, well-tolerated and manageable with the help of a caregiver.

To learn more about how Alzheimer’s develops and what you can do about it, watch this video:

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Eating disorders

Thus far, there haven’t been any published studies of low-carbohydrate diets for eating disorders. However, in my clinical practice, people with binge eating and bulimia who try a low-carbohydrate diet often experience relief from binge behaviors, because their cravings usually diminish significantly. Since binge eating triggers the impulse to purge, LCHF can be a very helpful strategy for people with bulimia who are willing to change their diet. Dairy and/or nuts can also trigger urges to binge in some people, so sometimes those foods need to be eliminated as well for best results.

Although no randomized clinical trials exist, a published case report demonstrated the successful use of a ketogenic diet in three subjects with binge eating and food addiction symptoms. Not only did they lose between 10 and 24% of their body weight, but they also reported reductions in binge eating episodes and food addiction/craving symptoms. This mirrors the clinical experience of many and is encouraging for future research efforts.

However, if you have a history of undereating or have ever had anorexia, anorexic thought patterns, or are uncomfortable with eating fat, a low-carbohydrate diet may not be right for you. When you dramatically reduce carbohydrate, you must replace those calories with calories from healthy fats. If you can’t increase your fat consumption substantially, a low-carbohydrate diet could be deadly, especially if you are already underweight or malnourished. If you are considering a low-carbohydrate diet, please seek medical and psychiatric consultation to discuss the risks and benefits as they pertain to your personal history and goals.

Summary

Although the food-mood link is still an emerging field of study, there is great potential for many to unlock better mental health by modifying our modern diets and giving up processed food.

For more on the role of sugar in mental health, and why you may feel better if you cut back on sugar and starch, please see our guide, How sugar may damage the brain.

But how do you begin a low-carb diet? And how might psychiatric medications be affected? Please see our guide about easing into a low-carb diet if you are taking medication for mental health issues.

And don’t miss our FAQ: Answers to common questions about low-carbohydrate diets for mental health!

/ Dr. Georgia Ede, MD

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