Nigel Smith / People: How Sydney Sweeney Lost 30 Lbs. in 7 Weeks Between Christy and The Housemaid: 'I Had to Be Really Strict' - The rest of her weight loss journey involved a "super clean" diet and "a lot of cardio," she tells PEOPLE - Sweeney Sweeney gained over 30 pounds to believably embody boxer Christy Martin in Christy