Quick answer: Research, largely in animals, suggests intermittent fasting may support brain health. Fasting may raise BDNF, a protein that supports brain plasticity, activate cellular stress-resistance pathways (hormesis), lower inflammation and oxidative stress, improve metabolic health and support mitochondria. Some people also report clearer focus, though experiences vary.
Key takeaways
Fasting has been shown to raise BDNF, a protein that helps brain cells grow and connect, at least in animal studies.
It may also support the brain by encouraging autophagy, antioxidant defenses and better insulin sensitivity.
Some people feel more focused while fasting and others feel irritable or preoccupied with food, so stopping is wise if your mood suffers.
Brain plasticity and BDNF
Brain-derived neurotrophic factor (BDNF) helps neurons grow and form connections. Fasting has been shown to increase BDNF in animal studies.
Signaling pathways
Fasting affects signaling pathways that influence brain plasticity.
Lower inflammation and oxidative stress
By encouraging autophagy and antioxidant defenses, fasting may protect brain cells. See autophagy.
Hormesis and stress resistance
Mild stressors like short fasts may trigger adaptive responses that make cells more resilient.
Metabolic and mitochondrial health
Better insulin sensitivity and healthy mitochondria support steady energy for the brain. See fasting and mitochondria.
Psychological effects
Some people feel more focused and in control; others feel irritable or preoccupied with food. If fasting affects your mood negatively, stop.
Healthy aging lens
Brain health depends on metabolic health, low inflammation and good sleep. Fasting is one possible tool, not a requirement.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have diabetes, take blood sugar or blood pressure medication, or have a chronic condition, or if you are pregnant, breastfeeding, underweight, or have a history of disordered eating. The same is true if fasting leaves you dizzy, shaky or exhausted, or if you want a fasting approach tailored to your health goals.
See a medical provider promptly for fainting, confusion, chest pain, a racing heartbeat, or very low blood sugar symptoms such as shaking, sweating and confusion.
What the research shows
Calorie restriction has been tested for memory. In a 2009 study by Witte and colleagues, 50 healthy older adults, average age 60, were placed in a 30% calorie restriction group, a higher unsaturated fat group or a control group for 3 months. Verbal memory scores rose by 20% only in the calorie restriction group, alongside lower fasting insulin and C-reactive protein, while BDNF did not change. This was calorie restriction rather than intermittent fasting, and the groups were small.
Mood has been studied in a combined approach. In a 2013 randomized trial by Hussin and colleagues in Malaysia, 32 healthy men aged about 60 followed calorie restriction with twice-weekly fasting or kept their usual habits for 3 months. The fasting group had less tension, anger and confusion and more vigor, but depression scores did not change. The trial was small, included only men and was not blinded.
Want a fasting plan that fits your health?
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Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Given my mood and focus, is fasting likely to help me or add stress?
Could fasting affect my focus and mood in a good or bad way?
How should I adjust fasting if I feel foggy or irritable?
Is fasting a good idea for me if I have a history of disordered eating?
Frequently asked questions
Does intermittent fasting improve focus?
Some people report it; research is still developing.
What is BDNF?
A protein that supports brain cell growth and connections.
Can fasting affect mood?
It can go either way. Stop if it worsens mood or eating behaviors.
Is fasting safe for people with depression?
Talk with your provider first.
Sources
- Witte AV, Fobker M, Gellner R, et al. Caloric restriction improves memory in elderly humans. Proc Natl Acad Sci U S A 2009. PMID: 19171901. https://pubmed.ncbi.nlm.nih.gov/19171901/
- Hussin NM, Shahar S, Teng NI, et al. Efficacy of fasting and calorie restriction (FCR) on mood and depression among ageing men. J Nutr Health Aging 2013. PMID: 24097021. https://pubmed.ncbi.nlm.nih.gov/24097021/
- Marosi K, Mattson MP. BDNF mediates adaptive brain and body responses to energetic challenges. Trends Endocrinol Metab 2014. PMID: 24361004. https://pmc.ncbi.nlm.nih.gov/articles/PMC3915771/
- Mattson MP, et al. Intermittent metabolic switching, neuroplasticity and brain health. Nat Rev Neurosci 2018. PMID: 29321682. https://pmc.ncbi.nlm.nih.gov/articles/PMC5913738/
- Longo VD, Mattson MP. Fasting: molecular mechanisms and clinical applications. Cell Metab 2014. PMID: 24440038. https://pmc.ncbi.nlm.nih.gov/articles/PMC3946160/
- Mattson MP. Hormesis defined. Ageing Res Rev 2008. PMID: 18162444. https://pmc.ncbi.nlm.nih.gov/articles/PMC2248601/
- Watkins E, Serpell L. The Psychological Effects of Short-Term Fasting in Healthy Women. Front Nutr 2016. PMID: 27597946. https://pmc.ncbi.nlm.nih.gov/articles/PMC4992682/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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