The Math Mom: How Patrick Dempsey and HDTV may be responsible for obesity.

Queen Latifah apparently lost 20 pounds recently, and Kelly Osbourne dropped 40 pounds. Too bad we cannot notice this, because most of us perceive them on TV as being 1/3 heavier than they actually are. They are being stretched in the least favorable dimension (that being horizontal, for those who are fortunate not to know).

Confused by the imminent digital TV switch deadline, and lured in by advertisers promising something bigger, flatter, brighter and sharper, many of us went and bought new HD TV sets. The high-definition picture does appear better because it is digital, has a greater resolution, and you usually watch it on a larger screen. But the HD format also has a very different proportions (width-to-height ratio, called aspect ratio) of 16:9. It is the same as a movie theater screen. The problem is that most of the TV programs are still not in high definition format. They are produced in a standard format with 4:3 width-to-height ratio. Ratio of 4:3 is the same as 16:12 and 12:9. This means that when we fit a standard TV program or a movie (with proportions 4:3 or 16:12 or 12:9) into our new HDTV screen (with proportions of 16:9) we have to either stretch the picture, or zoom and cut some of the frame.

Let's take Patrick Dempsey, voted TV's hottest gentleman. Assume that Grey's Anatomy is broadcast via a standard definition TV signal with image proportions of 4:3.

Displayed on a high definition TV set, the standard definition image is lost against a black background:

HD TV sets allow us to enjoy the wide format of the screen by offering a number of display options for a standard definition signal. The most popular among them are zoom and stretch. The Zoom option leaves the image undistorted but cuts the image’s margins, which frequently includes people's heads:

Remembering how much this TV costs and dissatisfied with missing information from the frame’s margins, many choose the Even Stretching or Full option. It distorts the content, but nothing is lost:

When image of standard TV proportions of 4:3=12:9 is being stretched horizontally to fit 16:9 aspect ratio, what has been displayed on 12 inches becomes 16 inches. Everything starts to look 4 inches wider, which can be translated to 1/3 fatter. Surprisingly, we are getting used to it quickly. And who knows, maybe it can explain obesity...

The scary part about this is that for many of us, TV is a window to the outside world. We frequently believe things are as they appear on TV. As we get used to newsmen and women with round faces, and compact cars stretched like limos, we may be disappointed to discover the real size of things.