Written by Dr. Nathan Gershfeld, D.C., founder of Fasting Escape and former staff doctor at True North Health Center.
Water fasting produces measurable improvements in mood, mental clarity, and emotional resilience in many of the people I supervise. These changes are not subtle. By the second week of a fast, people who came in feeling mentally foggy, emotionally flat, or chronically anxious often describe a clarity and lightness they have not felt in years. The research is still catching up to what clinicians have observed for decades, but the pattern is consistent enough that mental health improvement is one of the most reliable outcomes I see.
Why Fasting Affects the Brain
The brain is not separate from the body. It is subject to the same inflammatory processes, blood sugar fluctuations, and metabolic dysfunction that drive chronic physical disease. In fact, many of the same root causes that produce high blood pressure, type 2 diabetes, and autoimmune disease also contribute to depression, anxiety, and cognitive decline. This is the cluster effect: chronic conditions rarely travel alone, and mental health conditions are part of that cluster more often than most people realize.
When you fast, several things happen that directly affect brain function.
Blood sugar stabilizes. The dramatic spikes and crashes produced by a modern diet, particularly one high in refined foods, have a direct effect on mood and cognitive performance. Less appreciated is the role of animal foods and dietary fat in driving insulin resistance, which makes blood sugar regulation progressively harder over time. People who eat this way often experience energy crashes, irritability, difficulty concentrating, and low mood tied to their blood sugar cycle. During a fast, that cycle stops entirely. Blood sugar stabilizes, and with it, mood often stabilizes as well.
Inflammation decreases. Neuroinflammation, inflammation in the brain, is increasingly recognized as a secondary factor in depression and anxiety. Fasting has a consistent anti-inflammatory effect throughout the body, including the brain. Markers of systemic inflammation drop during extended fasting, and this likely contributes to the mood improvements people report.
Autophagy clears cellular debris. Extended fasting activates autophagy, the body’s cellular cleaning process. In the brain, autophagy helps clear damaged proteins and dysfunctional cellular components that accumulate over time. This process requires days to weeks of fasting to become meaningful not the 16 hours of intermittent fasting that is often discussed in this context.
A Note on Anxiety and Depression During Fasting
It is worth addressing something I see often in the people I work with. Many people who describe themselves as anxious or depressed are not experiencing a primary psychiatric condition. They are experiencing a completely understandable psychological response to watching their health decline: The frustration of being told their conditions are permanent, the helplessness of taking medications that manage symptoms without addressing causes, the grief of losing physical capacity and quality of life.
When fasting and a health-promoting diet begin to reverse those conditions, when blood pressure normalizes, when blood sugar stabilizes, when chronic pain decreases, the anxiety and depression frequently resolve along with them. Not because fasting is a psychiatric treatment, but because the underlying cause of the emotional distress has been removed. This distinction matters. It means that for many people, mental health improvement is not only a side effect of fasting. It is a direct consequence of getting physically healthier.
What I See Clinically
The mental health changes I observe during supervised fasting follow a fairly predictable pattern.
The first two to five days are typically the most intense. People feel the withdrawal from stimulants — caffeine, sugar, salt, processed food — and this can produce headaches, irritability, low mood, and fatigue. This is not a sign that something is wrong. It is the body recalibrating. I tell people to expect this and not to interpret it as evidence that fasting is not working.
By days five through seven, something shifts. The discomfort recedes and a kind of quietness sets in. People describe it differently. Some say they feel calm, others say clear, others say present in a way they have not felt in a long time. The mental noise that characterizes modern life, the constant stimulation, the craving, the mental chatter, all of this quiets down considerably.
By the second week, the changes are often striking. During my daily check-in calls, people who began the fast describing themselves as anxious, overwhelmed, or emotionally numb frequently report feeling emotionally better and even optimistic. These are not people who came to me specifically for mental health treatment. They came for blood pressure, weight loss, or autoimmune conditions. The mental health improvement is often a surprise to them.
Fasting and the Pleasure Trap
Any honest discussion of fasting and mental health has to address the Pleasure Trap, a concept developed by Drs. Doug Lisle and Alan Goldhamer that explains why modern processed food is so psychologically powerful and why breaking free from it is so difficult.
The modern food environment is engineered to hijack the brain’s reward system. Hyper-palatable foods — high in salt, fat, and sugar — produce dopamine responses that dwarf anything found in nature. Over time, the brain recalibrates around these artificial highs, making natural foods taste bland and making the idea of going without food feel genuinely threatening.
During a fast, the brain’s reward system gets a full reset. Without the constant stimulation of hyper-palatable food, dopamine sensitivity gradually normalizes. By the time the fast ends and refeeding begins, whole plant foods – foods that may have tasted dull or unsatisfying before – taste remarkable. This is the taste bud reset, and it is one of the most important and underappreciated outcomes of extended fasting.
The psychological significance of this reset is profound. People who have struggled for years with food cravings, emotional eating, and the inability to sustain a healthy diet often find that after a fast, the cravings are simply gone or substantially reduced. The pull of processed food has weakened. Whole food feels genuinely satisfying. This is not willpower, it is neurological recalibration.
Medications and Mental Health
If you are currently taking psychiatric medications, antidepressants, mood stabilizers, anxiolytics, or others, water-only fasting is not appropriate until those medications have been eliminated under proper guidance. Many psychiatric medications require food for proper absorption, affect electrolyte balance, or interact with your body in ways that make water-only fasting unsafe while on them.
This does not mean fasting is off the table entirely. A modified fast using broth and juice may be appropriate in some cases, and this is something we can discuss during an initial consultation.
If reducing or eliminating psychiatric medications is a goal, that process needs to be guided by a clinician who is knowledgeable and experienced in deprescribing. This is a specialized area and not every prescribing physician has that experience. Finding the right support for that process is an important step before considering water-only fasting.
When Water-Only Fasting Is Not the Right Move
For people managing serious psychiatric conditions like severe bipolar disorder, psychosis, or other significant mental health challenges a remote, water-only fasting program is probably not the right starting point. The intensity of extended fasting, combined with the absence of in-person support, makes it a poor fit for situations where mental health stability is already fragile. This is where an in-person residential fasting clinic may be worth the cost.
That does not mean fasting has nothing to offer in the long term. But the sequencing matters. Stabilization first, with appropriate professional support, before considering the added demand of an extended fast.
For people whose mental health challenges are mild to moderate, tied to lifestyle and metabolic factors rather than serious psychiatric illness, the picture is very different. In those cases, fasting may be one of the most effective interventions available.
Book your initial consultation here to discuss whether a supervised water fast is appropriate for your situation.
Frequently Asked Questions
Can water fasting help with depression and anxiety?
For many people, depression and anxiety are responses to declining physical health rather than standalone psychiatric conditions. When fasting and a health-promoting diet begin to reverse the underlying health issues, the emotional distress often resolves along with them. For more serious psychiatric conditions, a remote water-only fasting program is probably not the right starting point and an in-person residential fasting clinic may be worth considering.
How long does it take to notice mental clarity during a fast?
Most people begin noticing improved mental clarity within a few days. The first two to five days are typically the most intense as the body withdraws from caffeine, sugar, salt, and processed food.
Can I fast if I am on antidepressants or other psychiatric medications?
Water-only fasting is not appropriate while on psychiatric medications. A modified fast using broth and/or juice may be possible in some cases. Eliminating psychiatric medications requires guidance from a clinician experienced in deprescribing before water-only fasting can be considered.
What is the taste bud reset and how does it affect mental health?
After several days of fasting, the brain’s dopamine response to food normalizes. Cravings for processed, hyper-palatable food weaken significantly. Whole foods become genuinely satisfying. This reset removes one of the primary drivers of food-related anxiety and is one of the most reliable outcomes of extended fasting.
Why do some people feel emotionally vulnerable during a fast?
Without food as a constant presence in daily life, some people find themselves more emotionally sensitive during a fast. This is a normal part of the experience and typically passes as the fast progresses.
Does the mental health benefit last after the fast ends?
It depends on what you do after the fast. People who gravitate more towards a whole-food, plant-based diet after fasting tend to sustain the mental health benefits. People who return to a processed food diet typically see those benefits erode over time. It is also worth noting that the refeeding period itself is a structured introduction to a healthier way of eating. Many people find that refeeding is where the dietary shift truly begins, and that the mental health improvements that started during the fast continue to deepen as the new diet takes hold.
See all the conditions we work with at Fasting Escape
Written by Dr. Nathan Gershfeld, D.C. Doctor of Chiropractic with 14 years of clinical experience in fasting and natural health. Dr. Gershfeld spent 6 years at the True North Health Center as an intern and staff doctor, then founded Fasting Escape, first as an in-person fasting clinic and now as a remote program bringing doctor-supervised fasting to people at home.