The Gluten Free Myth: most newly-diagnosed celiacs are scrawny and underweight. The Reality: 39% are overweight. 30% of newly-diagnosed celiacs are obese.
Determining which people should be diagnosed is a very challenging task, so I will not attempt to cover it in a single article. I should point out that it is very difficult (some would call it impossible) to get an accurate diagnosis of celiac disease when a person is already following the gluten free diet.