When I worked at the corp HQ for the self storage company based in Buffalo, NY, the office there was EXACTLY as you described. To the TEE! Every day, same topics, stories, diets etc. It was so predictable I often thought to myself "don't these women realize that this is all they do, and over and over again each and every day".
Hey, I am not a thin person by no means, but I'll be damned if I am going to stand around the office and swear up and down how "I am going to do it this time" and then walk away and go back to my desk and wipe out the peanut M&M's in the candy dish at my cube. Funny thing is, they did this stuff openly, talk about how they need to loose weight and then walk right to their desk, open the drawer and begin to eat an entire bag of Doritos.
It's was almost a comical routine to sit back and watch this each and every day. Wouldn't you think they would realize people hear them and then see them etc.? And then there is always the token 2 or 3 super skinny women in that same office who eat carrots for lunch every day, bowl of granola each morning etc. And here they could stand to put on a few pounds. LOL I think every office in the country has the same scenario, just different people...