Proposed mechanisms include an increased rate of aromatization of testosterone or a decreased rate of oxidation of oestradiol to oestrone. (academic.oup.com)
This can happen in 2 circumstances: lack of certain nutrient such as zinc, magnesium, selenium or vitamin D3 will either increase aromatization activity or prevent its inhibition, or your bodyfat is too high. (strengthsensei.com)
Fat around your stomach and internal organs, otherwise known as visceral fat increases the process of aromatization which increases the production of estrogen. (fitnessandpower.com)