Factors that block UVB radiation, such as sunscreen or melanin, and higher body fat impair vitamin D production.

“anything that blocks out UVB light like sunscreen or melanin which is the this dark dark uh skin pigment that protects us from the burning rays of The Sun Also impairs our ability to make vitamin D in addition body fat vitamin D is fat soluble it's stored in the fat and Studies have shown that the more body fat the less bioavailable vitamin D is to be released into the bloodstream”