What's Your Diet Deficit?

Anyone who's on a fad diet is painfully aware of some things now missing from the dinner plate. Oh, how you yearn for the simple things you took for granted -- the burger with the bun, the fast food bagel that didn't require your scraping three-quarters of the cream cheese off with a napkin, the simplicity of pouring a container of half-and-half into your coffee instead of letting the mug grow cold while you wait for the waitress to bring the pitcher of skim milk.

But not everything that your diet plan prohibits leaves such an obvious hole in your life. That may not be a good thing. Without your noticing it, your fad diet may be cutting out foods that give you important vitamins and nutrients you really need.

While losing weight is obviously great for your health, it isn't the only thing you need to worry about. But that's all any fad diet is designed to do. Good nutrition is often beside the point.

"I think people lose sight of nutrition when they're dieting," says Elisa Zied, RD, a spokeswoman for the American Dietetic Association. "But if you're not getting good nutrition, you're not going to feel well."

So besides those much-missed french fries and ice cream, what might you be leaving out of your diet? WebMD talked to some experts to find out what's missing from fad diet plans. In some cases, it may be quite a lot.

Do I Really Need to Worry About Nutrition?

Obviously, we don't mean to overstate the problem. You won't drop dead from a nutritional deficiency after a few months of following a fad diet plan. Our nation's emergency rooms aren't flooded with fad dieters laid low by scurvy and rickets.

But it's easy to underestimate the problem, too. Chronic nutritional deficiencies can make you feel rundown and unwell.

"I definitely see people who have nutritional problems from dieting," Zied tells WebMD. "You need to get laboratory tests to make sure. But sometimes it's obvious. Their skin is sallow, their lips are cracking, or they have bad breath."

Nutritional deficiencies can lead to more serious problems too, especially for people who already have other medical conditions. Many vitamins and nutrients have been shown to help prevent serious diseases, like cancer and heart disease. Sticking to an imbalanced diet for a long time may lead to serious consequences.

High-Protein Diets

High-protein/low-carb fad diets have come under some heavy criticism from the experts.

Zied speaks specifically about the Atkins diet, although many high-protein diets are what she calls "imbalanced diets." "By cutting out carbohydrates, it eliminates the food that is supposed to be the main source of fuel for your body," says Zied.

Many of the high-protein diets ignore the nutritional differences between different kinds of carbohydrates, experts say. But there's a world of difference -- nutritionally speaking -- between carbohydrates like refined sugar and a kiwi, says Elaine Magee, MPH, RD, the "Recipe Doctor" for WebMD's Weight Loss Clinic and the author of Fry Light, Fry Right.