With respect to the endocrine system, when you carry too much weight, it will affect
your hormone levels.
In the peripheral fat, testosterone gets converted to estrogen. So for overweight men, they literally begin to have higher levels of estrogen than they are supposed to have which will exacerbate the weight problem as well as begin to cause things like breast formation and breast tissue growth. That of course will also feed back on the natural hormones being produced in the testes and the coordination of all of it in the pituitary gland and hypothalamus and decreased natural testosterone production leading to low testosterone.
For overweight females, it’s okay to have estrogen, of course, however the excess estrogen that is produced in peripheral fat will affect cycles negatively and mess with the natural hormone balance. Women are very complex with testosterone, estradiol, progesterone, a multitude of other factors in their hormonal system.
So if you get excess estrogen coming from the peripheral fat, it can mess that whole
hormonal balance system up. This would lead to, once again, more weight gain, certainly increased risk for certain estrogen dependent cancers like endometrial or breast cancer.
It will mess with menstrual cycles and their regularity and intensity. So obesity affects hormones significantly as well.