Why Sudden Weight Gain Happens in Women After 35 As women enter their late 30s and 40s, hormone levels begin to fluctuate. One major factor is changing estrogen levels, which affect: Fat storage Muscle maintenance Appetite regulation Recovery from exercise This is why many women experience perimenopause weight gain even when their lifestyle hasn’t changed much. Common signs... https://www.freedomfromdiabetes.org/blog/post/hidden-cause-sudden-weight-gain-women-over-35/5244