Why treat mental health challenges with diet and/or nutrition?

I am not anti-medication at all.  There is a time and place for medication and I myself have been helped by them at times.  However, I have also seen that many, if not most, get only limited relief from psychiatric medications and some are not helped at all.  Often the side effects are impressive (sexual dysfunction and weight-gain being the side effects most likely to get our attention) and a risk/reward analysis frequently does not favor medication.  If you want to know more about risk/reward, check out the paper linked here about the efficacy of antidepressants and the additional paper showing that people build tolerance to them and need more and more medication to get the same effect (also known as “addiction”).  For many, dependency on medication can ultimately hinder healing and even create new challenges.  There is a growing body of evidence that diet/nutrition and lifestyle can offer even better outcomes for many without the risks and side effects.  Of course, that means changing things that some of us hold dear, so it requires some motivation to go this route.  I can speak from my own experience that the outcome can be very much worthwhile.  

How Does Diet Impact Mental Health?

While the technical answer is very complicated, here’s how I think about this question in order of importance for healing the brain and improving mental health symptoms:

1. Brain Energy—The brain prefers ketones (produced from fat) for its fuel.  The difference between a brain fueled primarily by glucose and one fueled primarily by ketones is night and day, kind of literally!

2. Nutrition—The brain has complex nutritional needs, many of which are not met by the modern American diet, even the “healthier” versions of it.  It turns out that the more plants you eat and the less meat you eat, the more likely you are to be undernourished in a number of important things the brain needs to function well.

3. Toxins and Antinutrients—Our food contains hidden toxins and antinutrients (which prevent the absorption of the nutrients we need).  Highly processed foods are full of these, but so are many plant foods that we think of as extremely healthy.  Eliminating or reducing exposure to these can improve brain function and overall health.

Modern American Diet Vs. Low Carbohydrate High Fat Diet

Let’s take a minute here to define the differences between when I am broadly calling “modern American diet” (MAD) and LCHF.  The MAD begins with the USDA Dietary Guidelines (https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials).  The USDA recommends that approximately 75% of our caloric consumption come from carbohydrate, with the remaining calories coming from low-fat meat and dairy.  For the first time in many decades of government guidance, the USDA is just now (2025) recommending that Americans REDUCE their intake of high-sugar foods and beverages.  I think most health-conscious Americans got the memo on this long before the USDA.

As a result of this historical guidance, the MAD ranges from the horrifyingly unhealthy end (highly processed packaged foods, high-sugar foods and beverages, high-carbohydrate fast food) to the healthier end that is often referred to as the “mediterranean diet”, though this description has limited basis in actual historical mediterranean eating and more to do with modern scientific projections on the regions.  This version is heavy on fruits, vegetables, grains, lean meat and some dairy.  Even on the mediterranean diet version, most people are consuming hundreds of grams of carbohydrate every day, which is converted to glucose in our digestive process.  More on what that means later.

LCHF eating reduces the consumption of carbohydrates, replacing those calories with high-quality fat and perhaps some additional protein.  The fewer carbohydrates we eat, the less glucose is available for fuel, forcing the body to switch to making ketones for fuel by burning either dietary fat or body fat.  LCHF also includes a range of dietary options in which people choose to reduce carbohydrates to below various thresholds and all the way down to effectively 0.  The latter is the “carnivore diet” you may have heard of and which I have been happily eating for some time.  

For those of you committed to eating a plant-based diet, I can tell you that you too can eat LCHF, but your nutrition will be so severely compromised that I can’t support this way of eating.  It feels unethical to me since I believe the nutritional impacts are too severe and the negative ramifications are not sufficiently offset by the better energy profile provided by LCHF eating, thus I choose not to advise clients who want to eat plant-based LCHF diets.

Ketones versus Glucose

You may have heard that the brain needs glucose (produced from carbohydrates).  There’s some truth to that because there are a few brain functions that require glucose for fast-acting fuel.  But it turns out that the liver can produce more than enough glucose from its own stores and that it can make those stores from fat and protein.  There is absolutely no need for carbohydrate to fuel the body or the brain.  Moreover, when both glucose and ketones are available to the brain, the brain will preferentially use ketones for fuel except for those few limited processes.  The brain makes the choice—it prefers ketones when it can get them.  On the modern American diet, where we eat primarily carbohydrates, ketones are generally not available and the brain is forced to use glucose for all of its processes.