I was a bit shocked at the amount of cultural shaming that was in effect to keep people thin back then (a "fattie" board game for kids - don't eat the junk food!) Clothing sizes have also dramatically changed. Normal looking kids these days were considered "plus size" in the 1950s. For what it's worth, there was a much lower incidence of eating disorders in the 1950s, as well.
From what I have compared in my own readings, the 1950s cultural shaming towards obesity is similar to the current French cultural shaming towards obesity. Some may think that it is cruel, but getting "soft" on fat has apparently made us more fat and has not reversed the incidence of disordered eating.
American Women Didn't Get Fat in the 1950sAmerican Women Didn't Get Fat in the 1950s is not a specific, prescribed diet. It takes a look at the culture, attitudes, medical advice and eating practices during that time period with suggestions on how you can apply an "outdated" way of eating, thinking and moving to your life.
She also has a blog.