At least initially, many low-carb plans restrict foods that are packed with fiber and vitamins proven to guard against disease. The result, experts say, is people are confused to the point of being scared of all carbohydrates.
With so many people new to the low-carb regime - and so little research available - the long-term health consequences remain unknown. While early studies on the Atkins Diet found it can reduce cholesterol in the short term, some doctors worry that people who stay on the plans for months or years will:
Not eat enough fiber, a risk factor for heart disease, stroke and cancer, especially colon cancer.
Miss out on cancer-fighting antioxidants and important nutrients such as vitamins C, folic acid and potassium, all found in fruits and vegetables.
Eat too many high-protein foods, straining their kidneys or causing calcium loss from bones.
Eat too many red meats and saturated fats, contributing to heart disease.
Suffer side effects including headache, dizziness, kidney stones, gout and dehydration.
"I worry because people can't see inside their bodies and see the damage they're doing," said Tracy Conder, a dietitian in Newport News. "It might not be an instant bad reaction."
To be fair, there are obvious health benefits to low-carb diets. The plans steer people away from processed and sugary foods such as candy, chips, soda, cakes, pastries and pies - foods long blamed for obesity and related health problems.
Everyone agrees that switching from white to whole-grain bread, rice and pasta is a good idea. So is eating low-fat protein sources such as fish and skinless chicken.
"A lot of this is what we've been preaching for years, with some different packaging," said Jenny Corley, nutrition supervisor for the Hampton Health District. "Some carb restriction is healthy."
There's also no denying that many people have lost weight on low-carb diets, although the verdict is out on whether they'll keep it off. Susan Dutt, a dietitian in Newport News, has noticed some people who stop the diets regain pounds even if they try to follow a well-balanced plan.
"Either they'll cheat because their diets have been so restrictive, or they'll find that their metabolism is different," Dutt said. "It seems like their body has to re-set itself, maybe because what they've been doing is unnatural."
Some foods that are high in natural sugars are still very healthy, Dutt said. Bananas, for example, are on the "don't" list for some diet plans even though they're high in fiber, vitamin C and potassium, which is important to muscle function and could lower stroke risk.
Comparing foods based on carb levels alone also is foolish, Pearson said. While a serving of broccoli has almost twice as many carbs as a serving of cauliflower, broccoli - like other colorful vegetables - has far more vitamins and nutrients.
"In terms of quality, it's like putting a Geo next to a Mercedes," Pearson said. Multivitamins and supplements can't make up the gap, she said.
In general, doctors fear the clamor over carbs is drowning out more valuable health messages - the need to control portion sizes, exercise regularly and drink plenty of water.
"If you do all of that, you're not going to have a weight problem," said John Brady, a family practice doctor in Newport News. "The key isn't to diet. It's to change your lifestyle."
Alison Freehling can be reached at 247-4789 or by e-mail at email@example.com.