Fatorexia: Overweight People Who Deny They Are Fat

The dangers of a distorted self-perception of being fat (as in anorexia) are clear, present and well-documented. But what about a distorted perception of being thin? Or at least "not fat"?
British author Sara Bird examines this phenomenon in her bookFatorexia: What Do You See When You Look in the Mirror?"
Bird herself was shocked to discover that she was overweight. At 5'10" and 238lbs, this may be hard for many to believe, but Bird says this of her epiphany;

When I looked in the mirror, I saw a confident thin person, when in fact I was obese.

Bird had developed what article author Suzanne Leigh described as a "magician's menu of optical illusions", which included:

• Wearing generously cut clothing with elastic waistbands
• Looking at hand mirrors to check her appearance, rather than full-length ones.
• Favoring ornate jewellery and fabrics to draw the eye away from the expanded flesh beneath.
• Using talc to avoid chafing, rather than stepping on the scales for a reality check.

Since the release of her book, Bird has been flooded with emails of people who shared her disillusionment. Says one of her readers

I've said for ages that I suffer from the opposite of anorexia. My friends are sizes 10 to 14, I'm a 20. But, when I'm with them, I think that I'm the same size as they are, until I see photos of us together. Then I have an almighty shock to see that I'm huge compared to them.

Science seems to back up Sara Birds' thesis. A study in the British Medical Journal found that one-quarter of obese or overweight adults did not view themselves as fat.
Experts say our self-delusions about weight appear to be fed by the apparel industry with its prevalence of "vanity sizing" - cutting clothing to appear more flattering and skewing sizes.
Bird has since dropped 20lbs through minor lifestyle changes, and advises a similar approach to fellow "fatorexics".

Fatorexia: big problem, minor problem, or no problem?

In my estimation, "fatorexia" is a legitimate concern for many individuals. Although I don't necessarily think that really obese individuals see themselves as thin per se, I do believe there is a significant amount of people who are in denial about their weight being problematic.
I don't think we'll see funding, support groups, or treatment centers for "fatorexia", but I don't think it would be a stretch to say it is a form of body dysmorphia.
What do you think? Is "fatorexia" a real problem, or just some pop-psychology buzzword with little significance?