Soy boy is a pejorative term sometimes used in online communities to describe men perceived to be lacking masculine characteristics.
[1][2][3] The term is based on the presence of the phytoestrogen isoflavone in soybeans, which has led some to claim that soy products feminize men who consume them, although there is a lack of evidence supporting the correlation between consumption of soy phytoestrogens and testosterone or estrogen levels[4] or sperm quality.
[6][7] As they are structurally similar to estradiol (the major female sex hormone) and have activity at the estrogen receptor.
[clarification needed][8] An article written in the 1970s claimed that soy could disrupt hormone balance which initially started the bad reputation,[9] [unreliable source?
The term has also been used in online debates about the fashion appeal of cargo shorts,[13] having a feminized and unathletic look, and an exaggerated smile called a "soy face" or "Soylent grin",[14][15] a reference to a meal replacement shake (itself named as a reference to the 1973 dystopian film Soylent Green).