Filled milk is skim milk that has been reconstituted with fats from sources other than dairy cows. Dairy milk from cows is of a certain quality, taste and texture that lends itself to the production of ice cream, sour cream, whipping cream, half-and-half among other dairy products. Removing milk fat and replacing it with other fats such as coconut oil or palm oil became a cost saving measure used by industry in the early 20th century. The United States Congress eventually banned such practices via the "Filled Milk Act" of March 4, 1923 (c. 262, 42 Stat. 1486, , which prohibited the shipment in interstate commerce of skimmed milk compounded with any fat or oil other than milk fat, so as to resemble milk or cream.

The issue of filled milk came to the forefront in United States v. Carolene Products Co. wherein Carolene Products Co. was indicted in the United States District Court for the Southern District of Illinois for violation of the Act by the shipment in interstate commerce of certain packages of "Milnut," a compound of condensed skimmed milk and coconut oil made in imitation or semblance of condensed milk or cream. The indictment stated, in the words of the statute, that Milnut "is an adulterated article of food, injurious to the public health," and that it is not a prepared food product of the type excepted from the prohibition of the Act.

Currently, filled milk is widely available in Asian supermarkets in the United States as "Milnot", a brand marketed as an evaporated milk substitute, by The J.M. Smucker Co..