"My observations have been that many Christians are quick to defend being overweight..."
I don't agree with the concept you're stating, although you might have meant something I would agree with-- that overeating and being lazy are sinful. Being overweight is just resulting evidence thereof. And Baptists, certainly those in the south and mid-continent, have a delight in getting together for meals which include lots of Calories, carbohydrates, fat, salt and (last but not least) sugar. No regard at all seems to be paid to all this eating and sharing recipes and joking about how we're overindulging such that this is the sinful part. Just thinking about our last church dinner or class party, or similar-- what did we make and bring? what did we eat? what did we hypocritically compliment? Can we even bring green beans to these things without added cream soup and something fried added to them? It's so ridiculous IMNSHO for Baptists to get so pugilistic about a few certain issues, but when it comes to healthy eating almost all of us need to be sent to a corner with the dunce cap for sinners.
I hear Baptists talking often about gorging themselves at buffets, get togethers, church gatherings and what not as if it is a sport, humorous, fun, acceptable, normal, a joke, and a good thing to do. Whenever the subject of over-indulging in food is brought up said become quite offended.
If however they hear a sermon (or statement) against alcohol, adultery, the "alternative" lifestyle, or whatever other sin they are not involved in, they get fired up and call it out. Then of course after said message off they are to the buffets. The buffets around here are filled on Sunday after noons with church-goers over indulging in eats.
I know, and spare me, I really don't know this is true, and it just simply cannot be true if it doesn't happen in your neck of the woods.
BTW: I wonder if this lifestyle falls into the category of practicing sin?