For a historian, it's reasonable to conclude that the attitudes towards size and fit displayed in a book, a film, a TV show, a comic book, etc, are those of the time the text was created. These change over time as texts are remade by new generations. For instance, think of the way the Batsuit has changed from Adam West's almost vulnerable-looking leotard and satin undies to Christian Bale's carapace-like Kevlar armour. And take a look at my old post comparing Honor Blackman's catsuit in the 1960s Avengers to Uma Thurman's in the 1998 movie.
But when it comes to period-set texts, we have a certain suspension of disbelief. We're prepared to take the author, the screenwriter, the production designer and costume designer's words for it that we are seeing an 'authentic' representation of a particular era.
But we are wise to be skeptical of these images as transparent visions of 'what it was like', because like any other reinterpretation of a text, they apply our own ideas about clothing size and fit. For instance, take what I reckon is the single worst-costumed period film of all time: the 1940 version of Pride and Prejudice starring Greer Garson and Laurence Olivier:
Jane Austen's Pride and Prejudice was published in 1813. They've got Darcy's look down okay, but Lizzie looks absolutely wrong. Her hairstyle is totally '40s with the upper hair in a smooth puff and lower hair in rolls curled towards the neck, whereas fashion plates and portraits of the early 19th century depict a chignon on the back of the head with small ringlets softly clustering around the temples.
Meanwhile, the voluminous skirt, nipped waist and shawl collar of her dress are far more contemporary than the Empire-waisted columnar silhouette of the period. The middle image of the three below is closer to how young women would have dressed at that time (more 1813 fashion plates are here)
I also want to include this image to show that while we tend to think of 'Regency fashions' as being relatively stable over time, they altered just as fashion always has and still does. In the image on the far right, you can see the migration of the waist closer to its natural point, and the broadening of the skirt to a bell shape.
Mind you, sometimes period costumes are quite accurate. Here is Queen Victoria's 1840 wedding dress, which was vastly influential for wedding fashions (not least of all, the tradition of brides wearing white):
And here is the dress Mia Wasikowska wore in last year's Jane Eyre (costume by Michael O'Connor). Jane Eyre was published in 1847 but Jane's wedding took place several years earlier than her narrative.
As I wrote a few years ago in a feature article about period film casting, "what we really seek from contemporary historical cinema are emotional truths: impervious to anachronism, resonating down the ages to reassure us of the universality of human experience."
In the service of this universality, costuming is often used as narrative metaphor. For instance, contemporary period dramas often use corsetry and voluminous dresses to mimetically convey women 'trapped' or 'subjugated' by class and marriage (for instance, in Marie Antoinette, Titanic and The Duchess).
Mad Men is set in the 1960s but similarly seeks universal emotional truths, even though its meticulous strivings towards period-accuracy are a key marketing strategy. Season 5 episode 3, 'Tea Leaves', which aired last week in the US, has a storyline in which Betty has become a sad, fat hausfrau. In the opening scene, her children struggle unsuccessfully to help her do up her dress…
…and she has to plead "a women's thing" (which isn't actually a lie – wardrobe malfunctions are often presented as a feminine failing) to avoid the humiliation of being seen to have gained weight.
Meanwhile at chez Draper, Megan slips easily into her own dress…
and is promptly zipped up by Don, cementing that Megan has just as easily slipped into Betty's place at his side. What makes this juxtaposition quite unfair, however, is the issue of ease. Betty's dress is super-fitted, whereas Megan's is loose through the dropped waist.
Later, at the doctor's office, Betty wears a horrible, boxy synthetic knit jacket. "Betty Draper – I almost didn't recognise you!" says an acquaintance who runs into her. Throughout the episode, Betty wears garish housedresses and dressing gowns in bright synthetics, as opposed to the cool pastel palette and sleek, fitted lines she wore in the show's earlier seasons.
Universality aside, I really appreciated a line of dialogue in which dropping a few pounds is referred to as "reducing" rather than the more familiar (to our ears) "slimming" or "weight loss". I've just finished reading Calories and Corsets, Louise Foxworth's excellent cultural history of dieting, in which she extensively quotes diet books and advertisements going back centuries. While reading the book I was struck by the way "reducing" or even "reducing flesh" was a favoured 19th- and 20th-century turn of phrase, and so I was pleased to see it in Mad Men.