The Antidepressant Effects of Intermittent Fasting: How and Why it Works

Dr. Tracey Marks, a psychiatrist, explains the neurobiological mechanisms through which intermittent fasting can have an antidepressant effect. The core mechanism involves increasing Brain-Derived Neurotropic Factor (BDNF), which is often low in individuals with depression. BDNF acts as "fertilizer for the brain," stimulating the growth of nerve cells in regions like the hippocampus, thereby enhancing brain plasticity and the ability to form new connections crucial for adapting to environmental changes. Additionally, BDNF increases serotonin levels, further contributing to improved mood. Fasting achieves this by increasing ketones, which directly trigger BDNF production, and by elevating ghrelin (the hunger hormone), which improves depression through its interaction with the chemical orexin.

The podcast details practical approaches to implementing intermittent fasting, emphasizing that it's a schedule adjustment rather than a restrictive diet. The most common method involves limiting one's eating window, with an ideal fasting window ranging from 16 to 18 hours. This means condensing eating into an 8-hour or 6-hour period, respectively. The speaker clarifies that any carbohydrates, including those from beverages like wine, count as food and extend the eating window, potentially negating the benefits of the fast. A three-step process is recommended: first, identify your current eating window; second, gradually increase your fasting window by an hour or two weekly; and third, assign specific times, often by pushing back breakfast to leverage sleeping hours for the fast.

Crucially, the effectiveness of intermittent fasting is contingent upon making healthy food choices during the eating window. The speaker warns against the common pitfall of overeating unhealthy foods due to hunger or a sense of entitlement after fasting, as the resulting inflammation can counteract any gains. Hydration is also highlighted as essential, recommending water alongside unsweetened coffee or tea to offset dehydration. The approach described is less drastic than 24-hour fasting, focusing on condensing eating times to avoid constant grazing and allow the body and mind to rest.

Finally, Dr. Marks addresses potential contraindications and considerations. She notes that the precise timing and strict schedule required for effective intermittent fasting might not be suitable for individuals with conditions like Obsessive-Compulsive Disorder (OCD) or Attention-Deficit/Hyperactivity Disorder (ADHD), as it could exacerbate their symptoms. Furthermore, the intense focus on eating schedules could potentially trigger or worsen eating disorders. The discussion underscores the importance of a personalized and cautious approach, integrating this lifestyle change with overall healthy habits and awareness of individual psychological vulnerabilities.

BDNF stands for brain-derived neurotropic factor and it's low in people who are depressed.

BDNF stimulates growth of your nerve cells in your hippocampus and other brain regions. And new cell growth is the mechanism behind brain plasticity.

Antidepressant medications increase BDNF and so does extended fasting.

Fasting increases ketones which trigger BDNF production.

An ideal fasting window to get this effect of the increased BDNF is about 16 to 18 hours for your window, your fasting window.

Notice I didn't say skip breakfast. You just want to push it back later.

What I described is not as drastic of a change as 24 hour fasting. Establishing these windows condenses the time that you eat so you're not grazing on food for all of your waking hours.

It's important to realize that intermittent fasting is not a diet. It's a schedule adjustment.

If you do this, the inflammation created by the unhealthy food offsets any gains from the extended fasting.

This gets nitpicky and very detailed and being on a strict schedule like this with precise timing may not work very well for a person with OCD or ADHD.