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What's Your Diet Deficit?

Many fad diets leave out more than the carbs, fat, or extra calories.

High-Protein Diets continued...

So what specifically might someone on a high-protein diet be missing?


  • Fiber, which is in many of the carbohydrates that are eliminated in high-protein diets, helps with digestion. It may also help prevent some serious diseases, such as heart disease.
  • Water. "Carbohydrates have a lot of water in them," says Zied. "So when you cut them out, it's easy to get dehydrated without realizing it."
  • Vitamins, such as A, B, C, and E, are plentiful in many high-carb vegetables, fruits, and grains.
  • Folic acid is in dark leafy greens and fruits and vegetables. It's also in many fortified foods, like cereals, that Atkins prohibits. Folic acid may reduce the risk of cancers, heart disease, and other problems.
  • Phytochemicals and antioxidants are in whole grains, fruits, and vegetables. "We know that these things can help prevent a lot of different diseases, including heart disease and cancer," says Tara Geise, RD, a spokeswoman for the American Dietetic Association.


Many experts also believe that high-protein diets allow far too much fat. And even protein can be a problem in large amounts. "Overloading on protein can harm your kidneys and affect your fluid balance," says Zied. For some people, especially people who already have kidney problems, these diets may be dangerous.

The South Beach Diet

The South Beach diet emphasizes an initial phase of low carbs but later changes to add more "good carbs." With this diet, you may be in danger of not getting enough fiber, vitamins A, B, C, and E, and important phytochemicals and antioxidants from carbohydrates.

However, many experts in diet and nutrition say the South Beach diet is more balanced and less risky than high-protein diets. The South Beach diet also distinguishes between beneficial carbs and those with little nutritional value. But the experts are more skeptical of this fad diet's emphasis on only eating foods that are low on the glycemic index. A food that has a low glycemic index by definition results in a slower and lower rise in blood sugar.

"My problem is that South Beach and some other diets teach people that bananas and carrots are bad because they have a high glycemic index," Geise tells WebMD. "But they're not bad because they're really high in good nutrients."

The Zone

Again, the premise of the Zone rests on eating more protein and fewer carbohydrates than a traditional diet. So the same risks apply: a deficiency of vitamins, fiber, and other nutrients. But like the South Beach diet, the Zone is a little less severe in its attitude toward carbs than Atkins.

"In theory, the Zone is a more balanced diet, although I still don't think people on it are getting enough carbohydrates," says Zied.

The Zone may pose a different sort of nutritional risk. "The Zone relies so much on the numbers that it's hard to follow," Geise says. "People just throw up their hands because they don't know how to get into the Zone." That kind of confusion can make it easy for people to lose track of their nutritional needs.

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