Watch It's Not Your Fault You're Fat (1970) : Full Movie Online Free Despite its condescending title, this documentary is a balanced self-help video about obesity and its causes in modern society. Celebrated nutritionist Dr. Gary Null looks at the biggest contributors to weight gain -- such as refined sugars and fast food -- and enlists the aid of a panel of experts to debunk fad diets. Ultimately, Nulls comes up with a program to help viewers lose weight and then keep the pounds off permanently.