Does Intermittent Fasting Help with Depression?

Depression affects hundreds of millions of people worldwide, and many are looking beyond traditional treatments for something that can help. Intermittent fasting has quietly gathered attention for its effects on brain chemistry, inflammation, and energy — all of which play a role in mood. But can fasting actually make a difference for someone dealing with depression?

The Short Answer

Intermittent fasting is not a treatment for clinical depression, and you should never use it as a replacement for professional care. That said, several of fasting's biological effects — reduced inflammation, increased BDNF, stabilised blood sugar — overlap directly with mechanisms that influence mood. Early research suggests fasting may have a mild antidepressant-like effect for some people.

What Happens in the Brain During a Fast

Fasting triggers a cascade of changes that affect how the brain functions. Three stand out as most relevant to depression:

BDNF (Brain-Derived Neurotrophic Factor) BDNF is often called "fertiliser for the brain." It supports the growth of new neurons, strengthens existing neural pathways, and plays a central role in mood regulation. People with depression consistently show lower BDNF levels. Fasting — even short fasts of 16–18 hours — has been shown to increase BDNF production. This is one of the same mechanisms behind why exercise can lift mood.

Inflammation Reduction Chronic low-grade inflammation is increasingly recognised as a driver of depression, not just a symptom. Inflammatory markers like TNF-α, IL-6, and CRP are elevated in many people with depression. Intermittent fasting reduces these markers significantly. A 2021 meta-analysis published in Nutrients (Berthelot et al., n=1,436) found that fasting reduced both anxiety and depression scores compared to control groups.

Blood Sugar Stabilisation Mood and blood sugar are tightly linked. Blood sugar spikes and crashes — common with high-carbohydrate diets — cause irritability, fatigue, and low mood. Fasting brings insulin down and keeps blood sugar stable, which smooths out the energy and emotional rollercoaster many people experience throughout the day.

What the Research Shows

A 2021 systematic review in Nutrients (Berthelot et al.) analysed 11 studies with 1,436 participants and found statistically significant reductions in both depression and anxiety scores in fasting groups compared to controls. The researchers found no increase in fatigue from fasting — a common concern.

A 2019 observational study in PLOS ONE (Wilhelmi de Toledo et al.) followed 1,422 people through supervised fasting of 4–21 days and found consistent improvements in mood, emotional wellbeing, and sleep quality. While this was not a randomised trial, the scale and consistency of the findings are notable.

Neither of these studies focused primarily on people with severe clinical depression. Most research to date examines general mood and subclinical depressive symptoms. The gap between "improved mood" and "effective treatment for major depressive disorder" is significant, and the evidence is not yet sufficient to bridge it.

Why People Often Report Feeling Better Emotionally When Fasting

Based on clinical observation and community feedback, several practical factors may explain mood improvements during fasting:

• Ketones are calming. When the body shifts to burning fat during a fast, it produces ketones. Ketones provide steady energy without the glucose crash that can cause mood dips. Many people describe feeling calmer and more even-keeled in ketosis.
• You feel in control. Depression often involves a sense of helplessness. Fasting is something concrete you can do. The sense of agency can itself have a mood-lifting effect.
• Sleep improves. Reduced inflammation and stabilised insulin often lead to better sleep quality, which is one of the most powerful natural influences on mood.
• Gut health improves. The gut produces around 90% of the body's serotonin. Fasting gives the gut time to repair, and the shift in gut microbiome diversity that comes with intermittent fasting has been linked to improved mood in early research.

Related Tips for Fasting and Mental Health

If you are considering fasting partly for mental health reasons, a few practical principles apply:

1. Fix the food first. Fasting on a diet full of sugar and processed food will likely make mood worse, not better. Stable food quality — clean proteins, healthy fats, leafy greens — is a prerequisite.

2. Don't go to extremes early. Starting with very long fasts when you are already struggling with low mood or energy can backfire. A 14–16 hour fast is enough to activate most of the brain-supporting mechanisms without adding excessive physiological stress.

3. Be patient. Mood benefits from fasting tend to become more noticeable after the first 10–14 days, once the body has adapted and hunger patterns have shifted. The first week is often the hardest.

4. Watch for warning signs. If fasting increases anxiety, causes persistent irritability, or makes low mood significantly worse, it may not be the right approach for you right now — particularly if you take medication for depression, as fasting can affect how medications are absorbed and metabolised.

A Note on Depression and Professional Care

If you are living with clinical depression, intermittent fasting should be considered a potential complement to — not a replacement for — professional treatment. That includes therapy, medication where relevant, lifestyle changes, and medical guidance. The research is promising but early.

What fasting may offer is a lifestyle framework that, when combined with improved sleep, better food quality, and reduced inflammation, creates conditions in which mood is more likely to stabilise and lift over time.

For the complete guide, get Intermittent Fasting in Practice on Amazon — and claim 3 months free on our fasting app at fastinginpractice.com/redeem

Frequently Asked Questions

Can intermittent fasting cure depression?

No. Fasting is not a medical treatment for clinical depression. It may support mood improvement by reducing inflammation and increasing BDNF, but it should never replace professional care or prescribed treatments.

How long does it take for fasting to improve mood?

Many people report mood stabilisation after 10–14 days of consistent fasting. The first week often feels harder as the body adjusts to a new eating pattern.

Does fasting affect antidepressants?

Fasting can affect how some medications are absorbed. If you take medication for depression, speak with your prescribing doctor before making significant changes to your eating pattern.

Why do I feel worse during my fast sometimes?

Irritability and low mood during fasting are most often caused by blood sugar drops or poor food quality in the eating window. Improving the quality of your meals — more protein and fat, less sugar and starch — usually resolves this within a few days.

Is intermittent fasting safe for people with anxiety?

Many people report reduced anxiety with sustained fasting, particularly once past the initial adaptation period. However, fasting can temporarily increase cortisol, and for some people this raises anxiety early on. Starting with shorter fasting windows (12–13 hours) and building gradually is the safest approach.

Related Articles

• How dopamine and serotonin affect fasting success
• Does intermittent fasting improve mood?
• Can fasting cause anxiety or irritability?

This article is for informational purposes only and is not medical advice. Always consult a qualified healthcare professional before starting any fasting protocol, especially if you have an existing health condition.