Image: A dressed-up Phyllis Lapin with Bob Vance
As The Office is a show about white people and men primarily; it is also a show about size-privileged people primarily. However, its focus on folks of size privilege is not myopic; of the regular cast, Kevin, Phyllis, and Stanley are all visibly fat, reflecting the reality of many nonfictional offices. Discrimination against their size is not ignored, but portrayed in a responsible and progressive way. Unlike most primetime shows, these characters are nuanced, three-dimensional players with lives independent of and often counter to stereotypes; their fatness is not erased, but instead a value-neutral part of their lives.
Fat people really aren't on television too often. Most series have very few fat series regulars. 30 Rock, for just one example, has just one not very positive fat character in its regular cast. Lost was mostly composed by folks who very accurately reflected what the kyriarchy would have you believe it means to look physically fit. Lost only had three regular characters who were not size privileged: Hurley, and less often Rose and Bernard. (I'll shut up about Lost now, promise!)
At the intersection of sizeism and sexism exists Phyllis Vance. Phyllis is active and healthy–she was a cheerleader and plays basketball and runs with the rest of The Office. Her health complaints are few–a history of scoliosis and some quickly-cured back trouble, neither coded as due to her weight (though Dwight makes a caddish comment to that effect). She is most closely compared to thin Pam, whom she has dressed similarly to on a couple of occasions, and whom she assertively tells not to threaten her client base. Phyllis is framed as attractive, happily married to Bob Vance (Vance Refrigeration). She is sexual and seems to like her body a great deal; in season six, she refers to her breasts proudly, has a quickie with Bob in a bathroom, and brags about flirting with men in bars. Her eating habits are not particularly healthy, but she's not guilty about them, they are not show to be a cause of her weight, and they are not unusual for The Office and their frequent birthday parties.
Michael does make jokes at Phyllis' expense–he attempts to make her into a matronly, asexual, harmless character by feigning attraction to her in the name of ridicule in a second-season episode (roundly recognized as sexual harassment) and later on claiming that she could not attract anyone (countered by her announcement of her engagement). But Phyllis does not reflect any of the stereotypes ascribed to older fat women. Phyllis is coquettish, not matronly. She is bossy and ambitious, not jolly. She is self-satisfied, not ashamed of herself. She is Phyllis Vance, and she's happy to be that.
Image: Kevin Malone with girlfriend Lynn
Kevin Malone is a hilarious character and a positive portrayal in some ways. He's healthy aside from a skin cancer scare early on. He's shown to be a basketball ace in a first-season episode, runs a 5k in the fourth season, and he has multiple romantic partners. He's not jolly, but monotonous.
But he's constantly shown to have cartoonish eating habits, sometimes forcing him into caricature and buffoonery. In one episode, the staff makes bets on the abilities and tendencies of other characters. Whereas talkative Kelly tells about her Netflix queue in infinitesimal detail, fat Kevin stuff M&Ms in his mouth. It's not explicitly "haha look at the fatty", and it's somewhat absurd. But, it's associating fatness with gluttony in a problematic way.
Stanley Hudson, wearing suglasses and a hat
Stanley Hudson is a pretty direct refutation of the jolly fat guy stereotype. He's the most direct rebuttal to Michael's constant ridiculousness. He is quite an amorous dude as well, with a wife and later a girlfriend. He's a well-developed character with specific likes (crossword puzzles) and dislikes (Michael). But unlike the other two fat series regulars, he is visibly unhealthy, having repeatedly voiced health concerns and experiencing coronary arrest, and avoiding activity (though he is sometimes physical). However, the show does not make a rhetorical point of connecting his fatness to his health problem beyond Michael being an ass about it, and showing him focusing on stress reduction rather than drastic changes in eating habits. Again, it's important that while Stanley is unhealthy, two other fat characters have few to no health issues.
The Office has also explicitly critiqued weight-loss culture (and especially its place in corporate culture). The "Weight Loss" episode portrayed corporate mandatory weight-loss programs as ineffective, harmful, humiliating, and not much fun. The group initially loses some weight, and then plateaus and even gains back–a reflection of the experiences of many dieters.
The project is also framed as harmful. The only character who feels better and healthier after the program is Stanley, who explicitly disassociates himself from its goals. Dwight goes overboard and humiliates Phyllis, Kevin, and Stanley, and endangers Phyllis by forcing her to walk five miles (both of these actions are rebuked by other characters). Michael Scott dresses in a fat suit and does his Michael Klump impression to the chagrin of the rest of the office. Kelly Kapoor discontinues eating and ends up in the hospital before renouncing dieting.
While Kelly Kapoor's eating is clearly disordered in this episode, the lives and experiences of folks with eating disorders are not appropriated; anorexia is not mentioned because it's clearly not anorexia that Kelly is experiencing. I suppose that these actions could be seen as mocking, but folks, I have done shit like this–try to lose weight as quickly as possible by eating next to nothing. It is a real impact of diet culture that is clearly shown to be inappropriate. Fasting in and of itself is not necessarily problematic, but it can be a practice that's used for self-harm, and The Office clearly critiques weight-loss culture through this depiction.
The Office is not a radical critique of dieting and weight-loss culture. It centralizes size-privileged people, and reinforces some problematic norms. But The Office does exist within the context of a media culture that frequently erases and usually stereotypes folks of size. By having a variety of well-developed, individual fat characters who do not conform to harmful norms and stereotypes, and by portraying weight-loss culture as harmful and problematic, The Office is sending a valuable and subversive message to its viewing audience.