According to WebMD, "For ALD, the cause is too much alcohol. You may be even more likely to get it if you drink a lot and Are obese Are malnourished Have chronic viral hepatitis, especially hepatitis C Have genes that make you more likely to get it Are an African-American or Hispanic male Age — the older you are, the more likely it becomes. The reason why some people with NAFLD have simple fatty liver and others get NASH isn't known. Genes may be a reason. NAFLD or NASH is more likely if: You're overweight or obese Your body doesn't respond to insulin as it should (called insulin resistance) or if you have type 2 diabetes You have high levels of triglycerides or "bad" (LDL) cholesterol, or low levels of "good" (HDL) cholesterol You're older You have polycystic ovary syndrome You have sleep apnea You have an underactive thyroid (the doctor will call this hypothyroidism) You have an underactive pituitary gland (you'll hear this called hypopituitarism) You're malnourished You've lost weight rapidly You've been exposed to certain toxins and chemicals You have metabolic syndrome. This is a mix of conditions that make you more likely to get type 2 diabetes and heart disease.With metabolic syndrome, you may have any three of these conditions: Large waist size High triglycerides or LDL cholesterol Low levels of HDL (good) cholesterol High blood pressure High blood sugar There are also some less common reasons why you may get NAFLD or NASH. They include: Medical conditions that affect how your body uses or stores fat Hepatitis C or other infections Fast weight loss Taking certain medicines such as glucocorticoids, methotrexate (Rheumatrex, Trexall), synthetic estrogen, tamoxifen (Nolvadex, Soltamox), and others Gallbladder removal. Some people who have surgery to remove their gallbladder are more likely to have NAFLD." https://www.eatthis.com/news-warning-signs-fatty-liver/