Chrissy, good evening I hope you are well and having a great Thursday night. With regard to your question, consider the following. There are for hormones responsible for muscle hypertrophy; testosterone, growth hormone, IGF-1 and insulin.Once adolescents occur, testosterone levels in boy’s increases from 20-60-ng/100 ml to 300- 600 ng/100ml. Girls’ testosterone levels stay at 20-60 ng/100ml.It is this lower level of testosterone which limits the potential for hypertrophy as compared to men.