Rachylou, I'm not sure that it's an optical illusion -- people get smaller near the coast here, too, at least between the prairies and the West coast. I've been told so by sales assistants in chain stores that are found across the country. The stock more small sizes in Vancouver than they do in Edmonton or Winnipeg. I'm pretty sure part of that must be population distribution, though. We've got a lot of Asian immigrants in Vancouver, and even their Canadian kids who were born here tend to be more delicately built than many white people.
Diana, what you say about cultural expectations is probably true. I asked my French sister-in-law, who was recently visiting, about the stereotype of the chic Parisian woman. She said that yes, it's a stereotype and she doesn't necessarily view Parisian women as universally stylish, but she did say that it's true that French women care more about how clothes look than how comfortable they are. She also said that French women pay a lot of attention to their waistlines. Being overweight is not as acceptable there.