The article says she would be considered plus sized by todays standards but she was actually tiny (22 inch waist as someone mentions in the comments) Another myth repeated until people believed it.
" Breakfast: She would warm a cup of milk on the hot plate in her room, then crack two raw eggs into it and whip the whole thing up with a fork.
Lunch: None.
Dinner: Marilyn would stop at the market near her hotel on the way home to pick up steak, lamb or liver, which she would broil and eat with 4 or 5 raw carrots.
Evening snack: She would stop at a local ice cream parlor for a hot fudge sundae, saying, “I’m sure that I couldn’t allow myself this indulgence were it not that my normal diet is composed almost totally of protein foods.”
http://blisstree.com/eat/marilyn-monroe-diet-exercise-819/#ixzz23tNecA3F
