Intermittent fasting has become a popular lifestyle trend, often praised for its role in weight management and metabolic health. But could it also help lower your cancer risk? New research is beginning to explore this link. In this article, we break down what science currently tells us about intermittent fasting and cancer prevention – what’s promising, what’s overstated, and what we still need to learn.
Intermittent Fasting (IF) involves eating much less food or no food for certain times in the day or week. It is a tool used for weight management, controlling blood sugar, and, more recently, it's been suggested as a way to reduce the risk of certain cancers. But is this true?
How Intermittent Fasting Works in the Body
Intermittent fasting (IF) is different from continuous caloric restriction, which is when total calories are restricted without prolonged fasting periods. Many studies show that caloric restriction leads to weight loss, reduced risk of heart attack and stroke, and improved blood sugar control. However, depending on how extreme the caloric restriction is, people often find it difficult to manage long-term1.
Intermittent fasting is a diet method that breaks down the day or week into fasted and fed times. In practice, overall caloric intake is reduced since there is a smaller window of time in which you can eat. IF is also a recognised method for weight loss, blood sugar control, and management of chronic inflammation2,3.
Metabolic changes and cell repair
Circadian rhythm is the internal body clock that helps regulate all the cells in your body. This can balance anabolic processes (building complex molecules, consuming energy) and catabolic processes (breaking down complex molecules, releasing energy) throughout the day4.
- Anabolic activity occurs during the fed window and is highest in the morning. Increased insulin signals for excess blood sugar to be stored in the muscle and liver. Protein is used to build muscle, and excess energy is stored as fat1.
- Catabolic activity occurs during the fasted window. In the evening, our bodies wind down, boost autophagy (cell clean up), and reduce inflammation1. After around 12 hours of fasting, low insulin levels result in the breakdown of energy stores in muscle, the liver, and fat tissue. Over time, this can improve insulin sensitivity and blood sugar control1.
Late-night eating can disrupt this rhythm, increasing health risks, but IF can help restore balance by increasing the window for catabolic activity and enhancing the activities of cells1.
Autophagy is a cell process that clears damaged components and abnormal cells, supporting health and potentially lowering cancer risk5. IF is thought to encourage autophagy through several different pathways5,6. One pathway, for example, involves increasing certain genes that may suppress early tumour formation by removing cells that have DNA damage6.
Inflammation and oxidative stress
Chronic inflammation is a process in which your immune system works overtime without a real cause. It can increase the risk of several diseases, including cancer5. Inflammation contributes to DNA damage, partly through the activity of harmful free radicals and oxidative stress.
When DNA damage occurs, cells can begin acting abnormally. They divide too quickly and may eventually form growths6.
IF can help reduce oxidative stress, which in turn could reduce DNA damage7.
What the Current Research Says About Fasting and Cancer
Lab models
Studies show that IF can suppress tumour growth across different cancer types:
- In models of colorectal cancer, IF resulted in fewer growths in the colon, and fewer of these growths were cancerous. Body weight also decreased, and overall gut health improved8.
- In models of breast cancer, IF reduced tumour size by 40-80 per cent. This was through increased cancer cell death, fewer signals that encouraged tumour growth, and increased activity of cancer-attacking immune cells9–11.
- In models of prostate cancer, IF slightly slowed tumour growth, reduced cancer cell numbers and hormone signals, enhancing the normal therapy used to treat prostate cancer12.
Though very exciting results, it is not completely clear if it is specifically the IF or general weight loss that provided these benefits. Findings in models are not always directly applicable to human studies, so what do human studies tell us?
Human studies and trials
There are a few small-scale trials and observational human studies that have promising results.
- Small clinical trials of less than 100 people show that IF is safe and feasible during cancer treatment. Some report that it can reduce the side effects of chemotherapy, like fatigue and nausea, while lowering insulin and growth factors that encourage tumour development13.
- Observational data suggests that longer fasting periods of over 13 hours can reduce the risk of breast cancer returning by around 36 per cent14.
- Currently, there are no large-scale randomised controlled trials (which are the gold standard for human studies) that investigate the effect of IF on cancer prevention or survival. Most studies focus on treatment support15,16.
Ultimately, IF cannot be clinically recommended for cancer prevention or treatment6, although there are always new studies taking place.
Potential Risks and Limitations of Intermittent Fasting
Not for everyone
Though early results are promising, IF is not suitable for everyone, for a variety of reasons, including:
- Eating disorders17
- Being underweight17
- Pregnant or breastfeeding18
- Diabetes that is treated with blood sugar-lowering medication19
- Any regular medication that may affect blood sugar19
Always consult a doctor or medical professional before starting IF to ensure it's safe for your health and lifestyle.
Lack of long-term human data
Good-quality clinical data is still emerging for IF and what effects it has on humans, particularly long-term. Large-scale trials with diverse populations of people over extended periods are needed to clarify the risks and benefits.
Why screening still matters
Prevention vs early detection
Intermittent fasting shows early promise for cancer risk reduction, but it cannot replace evidence-based screening and early detection.
The NHS health checks for people aged over 40 monitor blood pressure, cholesterol, and weight. These appointments offer a natural opportunity to discuss vague symptoms like fatigue, unexplained weight loss, or appetite changes that might signal early issues but may not warrant their own appointment20.
The earlier a cancer is identified, the more treatment options are available, improving survivability and quality of life. By the time symptoms arise, cancers have often advanced, so early detection is very important.
The role of Ezra Scans in proactive health
Ezra offers pre-emptive Magnetic Resonance Imaging (MRI) scanning to help empower people to take their health back into their own hands.
They offer a multi-region MRI scan that can look at up to 14 organs for early signs of cancer and over 500 other non-cancerous conditions.
Spotting these signs early provides multiple benefits and peace of mind.
Conclusion
Intermittent fasting shows exciting promise. It can potentially suppress tumours in models, ease chemotherapy side effects in small human trials, and reduce recurrence risk through metabolic shifts like autophagy and lower inflammation. However, these findings are very early days and need further investigation.
IF could be a very powerful tool for weight management and general health, but it is not appropriate for everyone. For cancer protection, early detection is one of the most effective tools.
Ezra scans use radiation-free MRIs to screen 14 organs, with the ability to spot 500+ conditions early to expand treatment options and boost survival. IF may lower risk factors, but early detection saves lives; don't skip check-ups or scans. Book your scan today.
Understand your risk for cancer with our 5 minute quiz.
Our scan is designed to detect potential cancer early.
Referencing
1. Vasim I, Majeed CN, DeBoer MD. Intermittent Fasting and Metabolic Health. Nutrients. 2022;14(3):631. doi:10.3390/nu14030631
2. British Heart Foundation. Intermittent fasting: is the 5:2 diet good for weight loss? British Heart Foundation. June 25, 2021. Accessed February 6, 2026. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/nutrition/ask-the-expert/fast-diet
3. My Health London NHS. Intermittent fasting. CVD. Accessed February 9, 2026. https://www.myhealthlondon.nhs.uk/be-healthier/lose-weight/which-diet-is-right-for-me/intermittent-fasting/
4. Zisapel N. New perspectives on the role of melatonin in human sleep, circadian rhythms and their regulation. Br J Pharmacol. 2018;175(16):3190-3199. doi:10.1111/bph.14116
5. Levine B, Kroemer G. Biological Functions of Autophagy Genes: A Disease Perspective. Cell. 2019;176(1):11-42. doi:10.1016/j.cell.2018.09.048
6. Wolska W, Gutowska I, Wszołek A, Żwierełło W. The Role of Intermittent Fasting in the Activation of Autophagy Processes in the Context of Cancer Diseases. Int J Mol Sci. 2025;26(10):4742. doi:10.3390/ijms26104742
7. Danovi S. Understanding the link between inflammation and cancer. Cancer Research UK - Cancer News. February 1, 2013. Accessed January 23, 2026. https://news.cancerresearchuk.org/2013/02/01/feeling-the-heat-the-link-between-inflammation-and-cancer/
8. Chen J, Su R, He Y, Chen J. Intermittent fasting inhibits the development of colorectal cancer in APCMin/+ mice through gut microbiota and its related metabolites. Front Microbiol. 2025;16. doi:10.3389/fmicb.2025.1563224
9. Das M, Ellies LG, Kumar D, et al. Time-restricted feeding normalizes hyperinsulinemia to inhibit breast cancer in obese postmenopausal mouse models. Nat Commun. 2021;12(1):565. doi:10.1038/s41467-020-20743-7
10.Clifton KK, Ma CX, Fontana L, Peterson LL. Intermittent fasting in the prevention and treatment of cancer. CA Cancer J Clin. 2021;71(6):527-546. doi:10.3322/caac.21694
11.Salvadori G, Zanardi F, Iannelli F, Lobefaro R, Vernieri C, Longo VD. Fasting-mimicking diet blocks triple-negative breast cancer and cancer stem cell escape. Cell Metab. 2021;33(11):2247-2259.e6. doi:10.1016/j.cmet.2021.10.008
12.Cordova RA, Elbanna M, Rupert C, et al. Caloric Restriction Enhances the Efficacy of Anti-Androgen Therapy in Prostate Cancer by Inhibiting Androgen Receptor Translation. Cancer Res. 2025;85(21):4182-4197. doi:10.1158/0008-5472.CAN-24-1986
13.Sucholeiki RL, Propst CL, Hong DS, George GC. Intermittent Fasting and Its Impact on Toxicities, Symptoms and Quality of Life in Patients on Active Cancer Treatment. Cancer Treat Rev. 2024;126:102725. doi:10.1016/j.ctrv.2024.102725
14.Marinac CR, Nelson SH, Breen CI, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016;2(8):1049-1055. doi:10.1001/jamaoncol.2016.0164
15.Maes J, Durieux V, Liebmann M, Salmon M, Preiser JC. Impact of intermittent fasting on patients with cancer undergoing chemotherapy and/or targeted therapies: a systematic review of the literature. Support Care Cancer Off J Multinatl Assoc Support Care Cancer. 2025;33(10):863. doi:10.1007/s00520-025-09907-7
16.Stringer EJ, Cloke RWG, Van der Meer L, Murphy RA, Macpherson NA, Lum JJ. The Clinical Impact of Time-restricted Eating on Cancer: A Systematic Review. Nutr Rev. 2025;83(7):e1660-e1676. doi:10.1093/nutrit/nuae105
17.Blumberg J, Hahn SL, Bakke J. Intermittent fasting: consider the risks of disordered eating for your patient. Clin Diabetes Endocrinol. 2023;9:4. doi:10.1186/s40842-023-00152-7
18.Giorno A, De Simone C, Lopez G, et al. Intermittent Fasting During Pregnancy and Neonatal Birth Weight: A Systematic Review and Meta-Analysis. Nutrients. 2025;17(22):3546. doi:10.3390/nu17223546
19.Shyamala R, Bhatia V, Mohanasundari SK. Effect of intermittent fasting on diabetic patients-A narrative review. J Fam Med Prim Care. 2025;14(9):3637-3641. doi:10.4103/jfmpc.jfmpc_1992_24
20.NHS. NHS Health Check. nhs.uk. November 6, 2023. Accessed January 15, 2026. https://www.nhs.uk/tests-and-treatments/nhs-health-check/
