Intermittent Fasting Lowered Anxiety and Changed Amygdala Brain Connectivity in a 50-Day Study: What the Research Shows

Intermittent Fasting Lowered Anxiety and Changed Amygdala Brain Connectivity in a 50-Day Study: What the Research Shows

Medical disclaimer: This article summarises published research for informational purposes only. It is not medical advice and is not a substitute for guidance from a qualified health professional. Always consult your doctor before starting any fasting protocol, especially if you have an existing health condition or take medication.

Study at a Glance

What This Study Looked At

Researchers set out to test whether a sustained daily fasting routine changes anxiety levels in healthy adults, and whether any such change shows up as a measurable shift in how the brain's amygdala — a region central to fear and emotional regulation — connects with other brain regions. Unlike most fasting research, which relies only on self-reported mood scores, this study paired psychological questionnaires with resting-state functional MRI scans, offering a rare look at a possible brain mechanism behind fasting's effect on anxiety.

Who Was Studied

Participant profile: 26 healthy adults; detailed age range and gender split were not available in the sources reviewed for this article. All participants served as their own baseline comparison, since this was a single-arm study design rather than a randomized controlled trial.

How the fasting protocol worked in this study: Participants restricted eating to a 6-hour daily window (fasting for the remaining 18 hours) every day for 50 days. Researchers assessed body mass index, blood glucose, insulin levels, insulin resistance, anxiety scores (Self-Rating Anxiety Scale), depression scores (Self-Rating Depression Scale), and resting-state fMRI connectivity of the amygdala at baseline, at three points during the fasting period (days 10, 30, and 50), and at two points after fasting ended (day 20 and roughly day 60).

What the Researchers Found

Anxiety and Metabolic Markers

• Anxiety scores dropped significantly during the fasting period and remained lower for roughly two months after the 50-day fasting period ended — the single most notable finding in the study.
• Metabolic markers (BMI, glucose, insulin, and insulin resistance) all moved in a favorable direction alongside the anxiety improvement, consistent with the broader relationship between insulin resistance and fasting seen across other studies.

Brain Connectivity Changes

• Using the bilateral laterobasal amygdala — a subregion tied to emotional regulation and anxiety-like responses — as the seed region for analysis, researchers found changes in resting-state functional connectivity between the amygdala and the postcentral gyrus, appearing at fasting days 30 and 50.
• The researchers interpreted this shift in amygdala connectivity as a plausible brain-based mechanism accompanying the drop in anxiety scores, rather than the anxiety improvement being a coincidence or purely a side effect of weight loss.

What Did Not Change

• The sources reviewed for this article did not report a specific numerical breakdown for the depression scale (SDS) results; the study's headline psychological finding was the anxiety score change rather than a depression change.

What the Researchers Concluded

The authors concluded that intermittent fasting reduces anxiety in healthy adults partly by modulating amygdala functional connectivity, and suggested this supports intermittent fasting as a potential non-pharmacological, low-cost approach worth further study for anxiety and related emotional regulation difficulties.

What This Means If You Fast

• A fasting-anxiety link now has some brain-imaging evidence behind it, not just anecdote. This is one of the few fasting studies to pair mood questionnaires with actual brain scans.
• The effect built gradually, not overnight. Amygdala connectivity changes appeared at day 30 and day 50 of an 18-hour daily fasting routine — this was a sustained, weeks-long pattern, not a single fasted day.
• This was studied in healthy adults, not people with a diagnosed anxiety disorder. It's reasonable to view this as encouraging general population evidence rather than proof of a clinical treatment effect.
• Metabolic improvement and mood improvement moved together. Lower insulin and blood glucose accompanied the anxiety reduction, echoing broader patterns seen in time-restricted eating research on insulin and metabolic health.
• Fasting doesn't feel calming for everyone, especially at first. Some people notice increased irritability or anxiousness in the early days of a new fasting routine before things settle — see our guide on fasting and anxiety for what's typical during adjustment.

Study Limitations

• No control group — as a single-arm study, it cannot fully rule out that factors other than fasting (season, life changes, simple time passing) contributed to the anxiety improvement.
• Small sample size — 26 participants is a modest number for drawing firm conclusions, especially for the brain-imaging component.
• Gender and age breakdown not available — the sources reviewed for this article did not specify the demographic split of participants, limiting how confidently the findings can be generalized.
• Healthy volunteers only — findings may not apply to people with a diagnosed anxiety disorder or other mental health condition.
• Full text inaccessible at generation time — PubMed and PMC direct access returned a 403 error; this summary relies on WebSearch-verified secondary summaries of the abstract rather than the complete published paper.

Source

Huo L, Li Y, Fu Y, Yang Z, Jia L, Li C, Zhang B. Effects of Intermittent Fasting on Anxiety and the Functional Connectivity of the Amygdala in Healthy Adults. Alpha Psychiatry. 2025;26(3):44384. PMID: 40630882

Frequently Asked Questions

Can intermittent fasting reduce anxiety?

This study found that healthy adults following an 18-hour daily fasting routine for 50 days had significantly lower anxiety scores, with the improvement lasting for about two months after the fasting period ended. It's promising evidence, though it comes from one small study without a control group.

How does fasting affect the brain and anxiety?

Researchers found that fasting was associated with changes in how the amygdala — the brain's emotional-regulation hub — connects with the postcentral gyrus, suggesting a possible physical brain mechanism behind the anxiety reduction, rather than the effect being purely psychological.

How long do you need to fast to see a mental health benefit like this?

In this study, measurable brain connectivity changes appeared at day 30 and day 50 of a daily 18-hour fasting routine — suggesting benefits may build gradually over weeks rather than appearing immediately.

Does intermittent fasting help with diagnosed anxiety disorders?

This study only included healthy adults without diagnosed anxiety disorders, so it cannot confirm whether the same effect would occur in people with clinical anxiety. Anyone with a diagnosed mental health condition should talk to their doctor before using fasting as part of their management plan.

Were there other benefits besides lower anxiety in this study?

Yes — participants also saw significant reductions in BMI, fasting glucose, fasting insulin, and insulin resistance during and after the fasting period, alongside the anxiety improvement.

Related Research and Articles

• Can Fasting Cause Anxiety or Irritability?
• Intermittent Fasting and Anxiety in Women
• Fasting and Mental Clarity: What the Science Shows
• Time-Restricted Eating: What the Research Says and How to Do It
• Insulin Resistance and Intermittent Fasting: A Complete Guide
• Intermittent Fasting, Anxiety and Depression: PHQ-9 and GAD-7 Research

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