Fat particles on the back are overproduction of sebaceous glands, or due to abnormal secretion, usually because the body’s sebum secretion metabolism is disturbed, excessive deposition, or the body has been unhygienic for a long time, not bathing, and not changing underwear for a long time resulting in fat particles on the back. Some fat particles can cause infection, patients will have local skin redness, redness, skin heat, and in serious cases, pus and abscesses. Long grease grains should be mostly youth, sebaceous glands secretion is more vigorous, and some will appear black, is due to androgen stimulation of hair follicle sebaceous glands during puberty, sebaceous glands secrete a lot of cortex, coupled with hyperkeratosis of hair follicle sebaceous gland ducts, sebum secretion blocking hair follicles, is a relatively easy to cure disease, or to comprehensive control, because oxidation becomes black, there is a white head inside, also called closed, no oxidation. Therefore, the long oil grains on the back may be due to abnormal secretion of sebaceous glands, etc.