I have been dieting due to fatty liver from obesity. i have lost 47lbs since march. is it safe for me to have some mashed potatoes and gravy?

Safe but not healthy: Congrats on the loss of 47 pounds! pretty much anything in moderation is ok. However, gravy is predominately fat; therefore if your goal is to reduce fatty foods a better choice would be a sweet potatoe with no gravy. Choose healthy carbs and avoid fatty foods like gravy to continue losing weight and improve your condition. Indulging in fatty foods is likely to leave you craving more.

Of course: Some fatty meals are OK. The low saturated fat/total fat that some hepatologists recommend in the setting of fatty liver disease, is an overall goal but "cheat" meals are fine.