Weighty issues

I went to a burlesque show last night, which I keep thinking of with mixed feelings. I had fun, it was very fun and funny, full of bad sexual puns and silly little skits. However, I also realize that it was quite bad. I mean, it was a Fairbanks burlesque show. It's not like there are tons of resources going into things like this around here. (I'm sure regular strip clubs here make bank, but while burlesque involves stripping it's more along peep-show lines, more artsy.) I have friends in Seattle who are involved in burlesque shows and all I could think was that they'd be weeping if they saw this.
The props were terrible. One of the two men had a fake mustache which kept falling off. At first I thought that it was supposed to add to the comedy, but when it kept happening I realized that, no, it was just bad.
The dancing...oh my word, the dancing. There were four women actually on stage, and only one of them was what you'd call thin. And she was awful. She couldn't dance worth anything. I wanted to shout, "Move your hips! No, not jerky motions, flowing! Like you're in water, dammit!" Instead of a sultry finger flowing up her body and then slowly pointing it upwards, she'd stab her finger into the air like she was trying to rip the ceiling.
The other three had varying levels of skill but only one of them was truly entertaining to watch. One of the women doesn't seem to have an expression other than scowling, so while she would otherwise be very pretty her expression was rather off-putting. The largest gal's "sultry expression" looked more vacant and dimwitted than anything else. I could see that part of it was because she was concentrating so hard, but I thought she would have done a much better job had she simply smiled. (I saw her later and she does have quite a nice smile. It was warm and friendly and she's very pretty when she smiles.)
Of course, it naturally got me thinking about weight as well. The only person involved with the show whom I would say was in shape was one of the men. Despite this, I don't want to make it seem like the weight of anyone on-stage was either off-putting or that I'm critiquing them for it. I just want to point it out because it got me thinking about weight in our society. You see, my friends who do burlesque in Seattle are all quite thin. It's expected that if you're going to be showing off your body, you should be in shape. Right? One of my friends, before she got back into doing burlesque, lost nearly 20 pounds. I saw her last summer and then again at Christmas and there was a marked difference. When I mentioned, at Christmas, how great she looked (she was all dressed up for New Year's and really did look gorgeous) she mentioned her weight loss. At the time I said something along the lines of, "Wow, good for you!" because that's the expected response. But I wasn't happy with myself for it.
Should we really congratulate each other on weight loss? I know that we put a lot of emphasis on weight. A lower weight does tend to correlate with a healthier person. I know that weight also isn't everything, though. When people mention weight loss I tend to be happy for them because, for the most part (at least among my friends) it means that they've been exercising more and eating better. And that is fantastic, I want to encourage that. I like my friends, I want them to live long and healthy lives! But I don't necessarily want to encourage the idea that weight loss is everything. I know plenty of people who are skinny but probably rather unhealthy, given what they eat and their amount of exercise. (I knew a guy several years ago, a senior at the U, who had never eaten a cherry, blueberry, or raspberry. He subsisted mostly on pb&j sandwiches and macaroni and cheese--it's what he'd eaten his entire life and he saw no need to change, or to eat fresh fruits and vegetables. I made him try a cherry.) Conversely, I know people who are overweight who eat well and run marathons. Weight is not necessarily a symbol of how well you take care of yourself.
Of course, those marathon runners who are overweight do tend to be outliers. Most of the people I know who are obese are in that category for a reason and I don't want to downplay that either. I get a bit googly-eyed when I hear about how much soda most people drink, or when I realize just how many times certain friends and acquaintances get fast food each week. Or the fact that some people don't exercise, ever.
So here's my conundrum. What do you say to someone who's lost weight if you don't want to be seen as congratulating them on the weight loss itself, but on the healthy habits they've developed? In what way can we have a conversation about weight and health which doesn't shame those who are overweight but otherwise healthy? That's a conversation I'd like to have, and one which I think is necessary for our national dialogue. As it stands, there are sweeping generalities about who is healthy and who is not, and it mostly ignores those who don't fit the generalities. Then people are offended and nothing productive occurs.
In this day and age, how do we address matters of weight without placing judgments on the wrong people?