Estrogen is best known for its role in the menstrual cycle, but it's involved in a lot more than reproduction. It supports bone density, contributes to cardiovascular health, and influences both mood and where the body tends to store fat.
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​Levels naturally rise during puberty and pregnancy, and body fat itself produces some estrogen — fat tissue isn't just a passive energy store, it's hormonally active. On the other end, menopause brings a significant, well-documented drop in estrogen, and very low body fat or chronic stress can lower it as well.
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​This is directly relevant to the weight changes many women notice around perimenopause and menopause. Declining estrogen is commonly linked to weight gain and a shift toward more abdominal fat storage — a pattern that's hormonal, not a personal failing, and one that often calls for adjusting expectations around diet and exercise rather than simply "trying harder" with the same approach that worked in your 30s.