Getting the "skinny" on it

I was reading one of the blog posts on spark people the other day and the particular post was a review of Heavy Weight Yoga, and the poster was saying how she had never been overweight so she doesn't understand what it's like but assumes that it would make certain activities more difficult. For some reason I have been thinking about that line for a day now. I've never really thought about the difference between listening to skinny people for advice or fat people or fat people that have lost the weight. Who knows best? Does anyone?
My nutritionist is very slender, I really respect what she has to say. Of course she's never pointed out that she doesn't understand where I'm coming from because she's never been fat like me. We talk about food like it's a science, and it's one that she's studied and it's good to understand, scientifically, what's going on inside my body. I have insulin resistance, so my science is out of whack. It's good to learn that.
So, why did it bug me the way the blogger started the review? I'm not quite sure. I think it was the quick way that she pointed out that she has no first hand knowledge of working out with extra pounds. But was that really necessary? I kind of feel like it came across like she didn't want anyone to confuse her with an overweight person. I am probably reading too much into it but it made me think about who I want to get my advice from.
For the science of it all, definitely someone trained. You don't need to understand "what it's like" if you've got the degree to back you up. However, beyond that. You guys are the ones I turn to. Who knows better than someone struggling with weight, what the struggles are like. How difficult ups and downs are, how we can workout and eat right for months and see absolutely no change. I think it's important for people that haven't gone through this to spend some time getting to know the struggles that we are all facing before dispensing advice. It's just not as easy as calories in vs. calories out.
Who are your best sources for weight loss information?