Research

Hormonal

Weight gain occurring between age 30 years and menopause is associated with a greater increase in breast cancer risk than weight gain occurring between age 18 and 30 years, although the difference in risk magnitude between these two periods is not statistically significant.

While gaining weight between ages 18 and 30 is less risky than gaining weight after 30, both increase risk compared to staying thin. However, if you gained weight in your 20s, you are not doomed; losing that weight in your 30s or after menopause brings your risk down to levels similar to women who never gained weight. Prioritize preventing weight gain after age 30, but know that correcting it later is highly effective.

GoodQualifiesMEDIUM confidence
Results seem to suggest that weight gain between age 30 years and menopause was associated with greater risk than weight gain between age 18 and 30 years.
Michelle Harvie et al. · Cancer Epidemiology Biomarkers & Prevention · 2005

Why this rating

Based on the same large prospective cohort with robust statistical modeling, though the specific comparison between the two gain periods was not statistically significant.

Source

Association of Gain and Loss of Weight before and after Menopause with Risk of Postmenopausal Breast Cancer in the Iowa Women's Health Study

Michelle Harvie et al. · Cancer Epidemiology Biomarkers & Prevention · 2005

DOI 10.1158/1055-9965.epi-04-0001

cohort · n=33660Cited 343×
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DOI resolved against Crossref · corpus check 2026-06-10

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