Whether it's Atkins, the South Beach or some other low-carb plan, as many as 30 million Americans are following a low-carb diet.

Advocates contend that the high amount of carbohydrates in our diet has led to increasing problems with obesity, diabetes, and other health problems. Critics, on the other hand, attribute obesity and related health problems to over-consumption of calories from any source, and lack of physical activity. Critics also express concern that the lack of grains, fruits, and vegetables in low-carbohydrate diets may lead to deficiencies of some key nutrients, including fiber, vitamin C, folic acid, and several minerals.

Any diet, weather low or high in carbohydrate, can produce significant weight loss during the initial stages of the diet. But remember, the key to successful dieting is in being able to lose the weight permanently. Put another way, what does the scale show a year after going off the diet?

Let's see if we can debunk some of the mystery about low-carb diets. Below, is a listing of some relevant points taken from recent studies and scientific literature. Please note there may be insufficient information available to answer all questions.

- Differences Between Low-Carb Diets

There are many popular diets designed to lower carbohydrate consumption. Reducing total carbohydrate in the diet means that protein and fat will represent a proportionately greater amount of the total caloric intake.

Atkins and Protein Power diets restrict carbohydrate to a point where the body becomes ketogenic. Other low-carb diets like the Zone and Life Without Bread are less restrictive. Some, like Sugar Busters claim to eliminate only sugars and foods that elevate blood sugar levels excessively.

- What We Know about Low-Carb Diets

Almost all of the studies to date have been small with a wide variety of research objectives. Carbohydrate, caloric intake, diet duration and participant characteristics varied greatly.

Most of the studies to date have two things in common: None of the studies had participants with a mean age over 53 and none of the controlled studies lasted longer than 90 days.

Information on older adults and long-term results are scarce.

Many diet studies fail to monitor the amount of exercise, and therefore caloric expenditure, while participants are dieting. This helps to explain discrepancies between studies.

The weight loss on low-carb diets is a function of caloric restriction and diet duration, and not with reduced carbohydrate intake. This finding suggests that if you want to lose weight, you should eat fewer calories and do so over a long time period.

Little evidence exists on the long-range safety of low-carb diets. Despite the medical community concerns, no short-term adverse effects have been found on cholesterol, glucose, insulin and blood-pressure levels among participants on the diets. But, adverse effects may not show up because of the short period of the studies. Researchers note that losing weight typically leads to an improvement in these levels anyway, and this may offset an increase caused by a high fat diet. The long range weight change for low-carb and other types of diets is similar.

Most low-carb diets cause ketosis. Some of the potential consequences are nausea, vomiting, abdominal pain, and confusion. During the initial phase of low-carb dieting some fatigue and constipation may be encountered. Generally, these symptoms dissipate quickly. Ketosis may also give the breath a fruity odor, somewhat like nail-polish remover (acetone).

Low-carb diets do not enable the consumption of more calories than other kinds of diets, as has been often reported. A calorie is a calorie and it doesn't matter weather they come from carbohydrates or fat. Study discrepancies are likely the result of uncontrolled circumstances; i.e. diet participants that cheat on calorie consumption, calories burned during exercise, or any number of other factors. The drop-out rate for strict (i.e. less than 40 grams of CHO/day) low-carb diets is relatively high.

What Should You Do? - There are 3 important points I would like to re-emphasize:

- The long-range success rate for low-carb and other types of diets is similar.

- Despite their popularity, little information exists on the long-term efficacy and safety of low-carbohydrate diets.

- Strict low-carb diets are usually not sustainable as a normal way of eating. Boredom usually overcomes willpower.

It is obvious after reviewing the topic, that more, well-designed and controlled studies are needed. There just isn't a lot of good information available, especially concerning long-range effects. Strict low-carb diets produce ketosis which is an abnormal and potentially stressful metabolic state. Under some circumstances this might cause health related complications.

The diet you choose should be a blueprint for a lifetime of better eating, not just a quick weight loss plan to reach your weight goal. If you can't see yourself eating the prescribed foods longer than a few days or a week, then chances are it's not the right diet. To this end, following a moderately low fat diet with a healthy balance of fat, protein, carbohydrate and other nutrients is beneficial.

If you do decide to follow a low-carb plan, remember that certain dietary fats are associated with reduction of disease. Foods high in unsaturated fats that are free of trans-fatty acids such as olive oil, fish, flaxseeds, and nuts are preferred to fats from animal origins.

Even promoters of the Atkins diet now say people on their plan should limit the amount of red meat and saturated fat they eat. Atkins representatives are telling health professionals that only 20 percent of a dieter's calories should come from saturated fat (i.e. meat, cheese, butter). This change comes as Atkins faces competition from other popular low-carb diets that call for less saturated fat, such as the South Beach diet plan. Low-carb dieting should not be considered as a license to gorge on red meat!

Another alternative to "strict" low-carb dieting would be to give up some of the bad carbohydrate foods but not "throw out the baby with the bath water". In other words, foods high in processed sugar, snacks, and white bread would be avoided, but foods high in complex carbohydrates such as fruit, potatoes and whole grains, retained.