A Theory on the Relationship Between Intermittent Fasting and Mental Health

You may have heard about the popular new practice of Intermittent Fasting. By simply restricting their eating to a shorter period of the day, people report increased mental clarity and focus, higher energy levels, and a wide variety of health benefits including reductions in weight, blood sugar, and cholesterol. The timing is not especially important — it can be 7am to 3pm, or 9am to 6pm — really any reduction in the continuous hours eating, with some research showing that stopping earlier is better.

What caught my attention the most was the claim that intermittent fasting has also been touted as a therapy for depression and anxiety. This potential benefit has not been well studied, and a likely mechanism has not been explained. So I will give it a shot.

The mechanism behind any and all of the reported benefits of intermittent fasting is surely multifactorial and complex. I will ignore the potential biological mechanisms and instead present a behavioral and psychological explanation for the reported benefits on focus, mental clarity, and mood.

Eating is a weird activity. Some people eat merely for sustenance, but most people derive some form of enjoyment from the act of eating. Given that, it is the practice of dosing yourself with a positive experience repeatedly until either 1. You are full and the pleasure of eating is outweighed by discomfort, or more commonly 2. When the food that is in front of you runs out. If you enjoy what you are eating, this activity is analogous to hooking yourself to a morphine drip that gives you a dose whenever you press a button. In this case, when you pick up the fork.

The mind molds itself to the situation it is in. If you sit down in a quiet room and meditate or just relax, the mind slows down. Thoughts come slower as your mind adapts to a new pace. If you walk around Times Square in New York City, with the people and the bright screens and the cars and the sounds and the smells… My mind is getting chaotic simply writing about it. In that environment, your mind will adapt to the faster pace.

Eating is more similar to Times Square than it is to the quiet room. It is a constant dose of stimulation via food and smell. More importantly, it is an active process instead of a passive one. While passive factors like your environment can mold your mind, active processes will mold it in a much more powerful and lasting way. You learn by doing better than by seeing. Eating is the active process of giving yourself a positive stimulus repeatedly. You take one bite and then immediately begin to crave the next bite, often while the first bite is still being chewed. Crucially, you then reward that craving with another bite, reinforcing the pathway of desire and immediate fulfillment.

As I will discuss in detail in my next post, desire (also described as attachment) is the root of all suffering. When you want things to stay the way they are now, you suffer when they change. When you want things to be different, you suffer when they stay the same. In no other instance can you seek pleasure and immediate fulfillment so effortlessly as when you eat. You are wiring a pathway in your brain to both crave pleasure and to reward that desire as fast as possible. Our species does this three or more times a day for our entire lives. That unquestionably changes the way our minds function.

This practice is fine while we are eating because we keep getting the dose of pleasure. But what happens when we finish the meal? That pathway of seeking immediate gratification has just been excessively reinforced, and the mind has adapted to it. If desire is the source of all suffering, then we are training ourselves to suffer.

This brings us back to intermittent fasting. We all need to eat, so complete fasting cannot be the answer. Currently, we spread our eating out more or less evenly throughout the day, like a drug-dosing schedule. By the time the brain remodeling is wearing off from breakfast we start the process again with lunch, and then with a snack, and soon after with dinner, and then soon after with dessert. We never let the mind recover from the anxiety-training activity of eating. We are giving our brain constant practice in desire.

By fasting intermittently, we can sequester the instances of desire-training to a smaller portion of the day. We minimize the impact that eating has on our minds. By only eating for a contiguous eight hours a day, the brain has a sixteen hour straight recovery period to break free of that pathway of pleasure-seeking.

What is the opposite of seeking? Peace. Complacency. Happiness.

A second factor to consider is stimulation, which is slightly different than pleasure. Even if what you are eating is not your favorite food, eating is still a very stimulating activity. Eating is supplying a constant stream of sensory input via taste and smell for as long as our meal lasts. When we are done, our brain is wired to continue seeking stimulation. This could explain the reports of improved clarity and focus from intermittent fasting. The extended period of time without the anxiety-inducing activity of eating helps to settle the mind.

Increased focus is nearly synonymous with mindfulness, and research shows that people are happier when they are mindful than when they are distracted, no matter the activity. This could further explain the reported benefit on mood and the potential of intermittent fasting as a therapy for anxiety and depression.

Of course, this is only a small part of a complex phenomenon. The relationship between the food we eat and our mental health is poorly understood, but the fact that there is a relationship is certain. Many other factors also affect the pathways of stimulation and pleasure seeking that I described, with cell phone use being the most salient.

The idea that the timing of food intake could have dramatic effects on health seemed far-fetched to me at first, but my proposed mechanism makes a lot of sense to me. Whether or not this proposed mechanism actually leads to the reported benefits will need to be studied before we can say with any certainty. While the mechanism is logical, there could be other biological or psychological effects of the schedule that interfere with the mechanism and counteract the potential benefit. As always, more research is necessary.