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

Advocates contend that high amount of carbohydrates in our diet has led to increasing problems with obesity, diabetes, and other health problems. Critics, on 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 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 initial stages of diet. But remember, key to successful dieting is in being able to lose weight permanently. Put another way, what does scale show a year after going off diet?

Let's see if we can debunk some of 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 diet means that protein and fat will represent a proportionately greater amount of total caloric intake.

Atkins and Protein Power diets restrict carbohydrate to a point where body becomes ketogenic. Other low-carb diets like 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 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 studies to date have two things in common: None of studies had participants with a mean age over 53 and none of controlled studies lasted longer than 90 days.

Information on older adults and long-term results are scarce. Many diet studies fail to monitor 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.

It's a fairly accepted 'fact' among college age women that they will gain weight their first year away from home. It's so well accepted, in fact, that nearly anyone will know immediately what you mean when you refer to 'Freshman 15'. The research doesn't quite bear it out, though. One study conducted 15 years ago found that incoming freshman did gain weight at higher rates than their peers who did not attend college, but average weight gain for stressful freshman year was 7 pounds, less than half mythical 15 pounds they'd been told to expect.

Even more encouraging is that a more recent study of college weight gain monitored weight and body fat of freshman women. More than half students put on weight, but for most it was less than five pounds. One third of students lost weight. Interestingly, those students who most worried about gaining weight believed that they had gained weight even when scales showed that they hadn't.

If you're concerned about gaining weight in that first year away from home, here are some concrete suggestions that can help you avoid dreaded Freshman 15.

Adopt a Healthy Attitude Toward Food.

Researchers place part of blame for Freshman 15 on tendency to turn to food for comfort. In an unfamiliar setting, with new stresses and new worries, students may turn to familiar foods that make them feel good to help them get through. Train yourself to eat when hungry - and deal with stress through other means.

De-stress.