# Intermittent Fasting for Longevity

Intermittent fasting reliably helps with weight, insulin sensitivity, and heart markers, but it does not beat plain calorie cutting for fat loss and there is no human evidence it extends lifespan. The 2025 BMJ network meta-analysis (99 RCTs, 6,582 adults) found IF matches continuous calorie restriction, with only alternate-day fasting adding a modest edge (~1.29 kg). Beginners should start with 16:8, but guard muscle mass with 1.2 to 1.6 g/kg protein and resistance training.

What the science actually says about eating patterns and aging

## On this page

- What Is Intermittent Fasting?
- Does Fasting Actually Slow Aging?
- What Are the Real Benefits?
- Who Should Not Fast?
- How Do You Start Safely?

## FAQ

- Will I lose muscle mass with intermittent fasting?
- Can I drink coffee during the fasting period?
- How long does it take to see results?
- Is it better to skip breakfast or dinner?

## Sources

- Mitchell SJ, Bernier M, Mattison JA, et al.. (2019). Daily Fasting Improves Health and Survival in Male Mice Independent of Diet Composition and Calories. Cell Metabolism. https://doi.org/10.1016/j.cmet.2018.08.011
- Di Francesco A, Deighan AG, Litichevskiy L, et al.. (2024). Dietary restriction impacts health and lifespan of genetically diverse mice. Nature. https://doi.org/10.1038/s41586-024-08026-3
- Acosta-Rodríguez V, Rijo-Ferreira F, Izumo M, et al.. (2022). Circadian alignment of early onset caloric restriction promotes longevity in male C57BL/6J mice. Science. https://doi.org/10.1126/science.abk0297
- Lowe DA, Wu N, Rohdin-Bibby L, et al.. (2020). Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters: TREAT. JAMA Internal Medicine. https://doi.org/10.1001/jamainternmed.2020.4153
- Liu D, Huang Y, Huang C, et al.. (2022). Calorie Restriction with or without Time-Restricted Eating in Weight Loss. New England Journal of Medicine. https://doi.org/10.1056/NEJMoa2114833
- Bartholomew CL, Muhlestein JB, Anderson JL, et al.. (2021). Association of periodic fasting lifestyles with survival and incident major adverse cardiovascular events in patients undergoing cardiac catheterisation. European Journal of Preventive Cardiology. https://doi.org/10.1093/eurjpc/zwaa050
- Brandhorst S, Levine ME, Wei M, et al.. (2024). Fasting-mimicking diet causes hepatic and blood markers changes indicating reduced biological age and disease risk. Nature Communications. https://doi.org/10.1038/s41467-024-45260-9
- Bauer J, Biolo G, Cederholm T, et al.. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: PROT-AGE Study Group position paper. Journal of the American Medical Directors Association. https://doi.org/10.1016/j.jamda.2013.05.021
- Semnani-Azad Z, Khan TA, Chiavaroli L, et al.. (2025). Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials. BMJ. https://doi.org/10.1136/bmj-2024-082007
- Stekovic S, Hofer SJ, Tripolt N, et al.. (2019). Alternate Day Fasting Improves Physiological and Molecular Markers of Aging in Healthy, Non-obese Humans. Cell Metabolism. https://doi.org/10.1016/j.cmet.2019.07.016
- Cienfuegos S, Gabel K, Kalam F, et al.. (2020). Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metabolism. https://doi.org/10.1016/j.cmet.2020.06.018
- Hofer SJ, Daskalaki I, Bergmann M, et al.. (2024). Spermidine is essential for fasting-mediated autophagy and longevity. Nature Cell Biology. https://doi.org/10.1038/s41556-024-01468-x
- Vendelbo MH, Møller AB, Christensen B, et al.. (2014). Fasting Increases Human Skeletal Muscle Net Phenylalanine Release and This Is Associated with Decreased mTOR Signaling. PLOS ONE. https://doi.org/10.1371/journal.pone.0102031
- Wilhelmi de Toledo F, Grundler F, Bergouignan A, et al.. (2019). Safety, health improvement and well-being during a 4 to 21-day fasting period in an observational study including 1422 subjects. PLOS ONE. https://doi.org/10.1371/journal.pone.0209353

_Full guide: https://longevity-germany.com/en/guide/intermittent-fasting_

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_Canonical: https://longevity-germany.com/en/guide/intermittent-fasting · Part of Longevity Cities · Updated 2026-06-22_