Weight and breast cancer.
What is the link?
Does being overweight increase my risk of breast cancer?
Being overweight or obese can help promote the growth of several cancers, including breast cancer. In women, there is a link between excess weight and breast cancer risk, but this depends on menopausal status. In men, excess weight is also linked to an increased risk of breast cancer.
In postmenopausal women, being overweight or obese increases the risk of breast cancer by up to 30%. In premenopausal women, being overweight or obese does not appear to be linked to an increase in breast cancer risk. However, they are associated with a variety of other health risks, including cardiovascular diseases, diabetes, and other cancers.
Tips for maintaining a healthy weight to reduce you risk.
The 50/25/25 split.
Aim for half your plate to be vegetables and divide the other half between protein and carbohydrates.
Ditch processed foods. Boost your fibre.
Avoid processed foods that are high in fat and added salt and sugar, eat fresh whenever possible. Eat plenty of high-fibre foods, such as fruits, vegetables, legumes, wholegrains and nuts.
Move your body daily.
Stay active with regular and varied physical activity. Aim for at least 150 minutes of activity per week. The more you do the better.
Key facts about weight and breast cancer risk.
- In 2022, 1 in 8 adults worldwide and 1 in 4 adults in the UK were living with obesity.
- Excess weight increases the risk of breast cancer in postmenopausal women by up to 30%.
- Excess weight is also linked to the risk of breast cancer in men.
- Excess weight does not appear to increase the risk of breast cancer in premenopausal women, although it may have other negative health effects.
- Sustained weight loss can reduce the risk of breast cancer in postmenopausal women.
How is your weight linked with breast cancer risk?
Being overweight or obese has complex effects on your body and your cells. It can affect your cell’s ability to grow and repair, your immune system, and, importantly for breast cancer risk, your hormone system.
Fat (adipose) cells can produce the sex hormone oestrogen. This is especially relevant for postmenopausal women as fat becomes the main source of oestrogen production after menopause. Having higher oestrogen levels can increase breast cancer risk.
In addition to oestrogen, fat cells can release a hormone called leptin. Studies have shown that higher leptin levels can increase the risk of developing breast cancer.
Weight gain and obesity can lead to long-term (chronic) inflammation within our bodies. This means that the immune system can be active when it shouldn’t be. Obesity-related inflammation can also encourage insulin resistance, which means that there may be too much sugar in the blood, leading to several health implications.
Can weight loss reduce breast cancer risk?
Weight loss, if maintained, can help reduce the risk of breast cancer for postmenopausal women. More research is needed to understand which types of weight loss interventions are the most beneficial. However, it has been suggested that avoiding weight gain may be a better breast cancer prevention tool than weight loss.
Ask the scientist: Does body weight increase my breast cancer risk?
Start your prevention journey today.
Take a moment right now to make one small, healthy choice today.
- Pledge to drink at least 2 litres of water throughout the day.
- Swap a sugary snack for a piece of fruit or vegetable sticks.
- Go for a short walk on your lunch break.
Each small action builds momentum. Start today to build a healthier, stronger you for tomorrow.
Further reading
For more information, read our Weight and Breast Cancer science review.
Last review: Feb-25 | Next review: Feb-28.
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- World Health Organization (WHO). Obesity and overweight 2024. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight (accessed September 4, 2024).
- National Health Service (NHS). Obesity 2023. https://www.nhs.uk/conditions/obesity/ (accessed August 8, 2024).
- World Health Organization (WHO). Obesity and overweight 2024. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight (accessed September 4, 2024).
- National Institute for Health and Care Excellence (NICE). Identification and classification | Diagnosis | Obesity | Clinical Knowledge Summaries 2024. https://cks.nice.org.uk/topics/obesity/diagnosis/identification-classification/ (accessed November 15, 2024).
- Reeves GK, Pirie K, Beral V, Green J, Spencer E, Bull D. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 2007;335:1134–9. https://doi.org/10.1136/BMJ.39367.495995.AE.
- World Cancer Research Fund (WCRF) International. Diet, activity and cancer - Cancer types - Breast cancer 2018. https://www.wcrf.org/diet-activity-and-cancer/cancer-types/breast-cancer/ (accessed August 18, 2024).
- Dehesh T, Fadaghi S, Seyedi M, Abolhadi E, Ilaghi M, Shams P, et al. The relation between obesity and breast cancer risk in women by considering menstruation status and geographical variations: a systematic review and meta-analysis. BMC Womens Health 2023;23. https://doi.org/10.1186/S12905-023-02543-5.
- Humphries MP, Jordan VC, Speirs V. Obesity and male breast cancer: Provocative parallels? BMC Med 2015;13:1–9. https://doi.org/10.1186/S12916-015-0380-X.
- Lees T, Cullinane A, Condon A, Shabaan AM, Humphries MP, Speirs V. Characterising the adipose-inflammatory microenvironment in male breast cancer. Endocr Relat Cancer 2018;25:773–81. https://doi.org/10.1530/ERC-17-0407.
- Devericks EN, Carson MS, McCullough LE, Coleman MF, Hursting SD. The obesity-breast cancer link: a multidisciplinary perspective. Cancer and Metastasis Reviews 2022 41:3 2022;41:607–25. https://doi.org/10.1007/S10555-022-10043-5.
- Chlebowski RT, Luo J, Anderson GL, Barrington W, Reding K, Simon MS, et al. Weight Loss and Breast Cancer Incidence in Postmenopausal Women. Cancer 2019;125:205. https://doi.org/10.1002/CNCR.31687.
