Dear Cecil: I've often heard people say "the camera adds ten pounds" when they're photographed. Is that just an excuse or is there any truth to it? Emma

Cecil replies:

No question there’s an element of denial here. Since you’re not looking at yourself most of the time, it’s easy to maintain a self-image reflecting the svelte physique you had ten years ago, as opposed to the corpulent wreck you’ve become. But that’s not the whole story. For reasons having to do with optics and the way your brain works, the camera can in fact make you look heavier than you are.

The main difference between a camera’s view of the world and yours is that the camera has a single “eye” whereas you have two. That subtly changes the way things look. Here’s an experiment. Pose a round object in front of a varied background — a coffee cup in front of the computer monitor worked well enough for me. From a distance of two or three feet, look at the object alternately with both eyes, then one. You’ll notice that, seen with one eye, the object looms larger in your field of vision, and obscures more of what’s behind it. It seems bigger and bulgier. In other words, it looks fat.

To find out why, look at the object first with your right eye, then your left. Notice the familiar shift in perspective known as parallax — background features hidden from one eye can be seen by the other. When you look at the object with both eyes, the brain blends the two views together. You see more of what’s behind the object, making it seem smaller. Result: binocular vision is slimming, monocular the opposite.

There are ways to compensate for the fattening effect of the camera. One is to use a telephoto lens when shooting portraits. Step back from the subject and zoom in — parallax, and thus the addition of pounds, diminishes with distance. (I knew a photographer who swore by the rule “Never use a lens whose focal length, in millimeters, is less than the weight of the woman.” Sexist thought? No doubt. Just saying it’s a guideline you might want to keep in mind.)

If you don’t have a telephoto lens but you do have digital photo-editing software, you can still step back when taking portraits and crop out the extra background later on the computer. If you’re on the other side of the camera, here’s some advice: watch out for amateur photographers who feel they need to have the subject fill the frame. They’ll tend to take portraits from three feet away, making it appear that your face has been painted on a balloon.

You say you’ve figured out how to compensate for the ten pounds added by the camera, but your subject is 20 pounds overweight? Still not a problem. There are other ways to make people look slimmer:

“Short lighting” can make a broad face look thinner. The subject turns one side of his or her face toward the camera and the photographer shines a studio light on the other side. Bright lighting on only half the face tends to elongate it.

Dress your subject in black and put him against a dark background, thereby concealing excessive circumference.

Have the subject turn at an angle to the camera, creating a narrower silhouette.

Let’s not forget those vertical stripes.

Get Mister Chubs to lay off the chimichangas. Not a terribly practical hint on the day of the photo shoot, but in the long run more likely to do him some good.

Dear Cecil:

How much nutrition do you get from eating corn? I know the day after I eat corn, what appear to be full kernels are released back into the wild. Does everyone have this condition?

— Just Being Corny, Reno

Cecil replies:

It’s not just you, my friend. A lot of us have had occasion to think, as one thinks of certain relationships: corn is just passing through. A corn kernel has a tough outer hull that’s about 90 percent crude fiber and none too digestible. However, the human body’s capabilities include an amazing process that enables us to get the most out of stubborn foods. It’s called chewing. Thus exposed, the inside of the kernel is loaded with nutritionally useful stuff — starch, sugar, protein, and oil. Think of the hull as a wrapper around a natural candy bar.

Even if you don’t chew it enough, corn probably still does you some good. My assistant Una calculates that at most 10 percent of corn’s bulk is truly indigestible. We’re assuming, of course, that your digestive juices manage to breach the hull, and I’m sure not going to say they don’t. To be on the safe side, though, listen to Unca Cecil: sit up straight, get lots of fresh air, and chew your food.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.