For the first two weeks of the Atkins diet plan (called Induction), carbohydrate intake is limited to 20 grams a day, meaning that protein and fat will, by necessity, form the bulk of the diet. In order to avoid health problems caused by vitamin and mineral deficiencies during this period, vitamin and mineral supplements form an essential part of this phase of the diet. 

After the initial two week period, carbohydrate intake is gradually increased until it reaches a level at which the dieter loses weight slowly and can reduce or eliminate the supplements. Once the target weight is reached, carbohydrate levels are again gradually increased until the dieter's weight becomes stable. Each of these carbohydrate levels varies from person to person. Dr. Atkins argues that many eating disorders are the result of hyperinsulinism, or excessive secretion of insulin, which, according to Atkins, causes food cravings and unstable blood sugar levels. Atkins claims that his diet stabilizes insulin and blood sugar levels, eliminating cravings and often reducing appetite.

Views in favor of the diet

Proponents of the diet mention that low-carbohydrate diets have been the subject of heated debate in medical circles for three decades [1], but are still "damned knowledge", so much so that until recently no serious research has been done on Atkins or other low carbohydrate diets. They mention that a few small research projects, as well as a great deal of anecdotal evidence, have shown such diets to help participants lose weight. 

A research study carried out by the Weight and Eating Disorders Program at the University of Pennsylvania, reported in May 2003 that the Atkins diet raised levels of HDL (or "good") cholesterol by an average of 11% and reduced the amount of triglycerides in the bloodstream by 17%. In the study, conventional dieters' HDL cholesterol raised by only 1.6% while their triglyceride levels did not improve significantly. Weight loss was also statistically greater in the Atkins dieters after three and six months compared with the conventional dieters (although this did not remain statistically significant after a year). The study followed the diets of 63 obese men and women. (See New Scientist, May 21 2003) Two other large-scale studies are planned, one funded by Atkins's nonprofit foundation. 

There are reports indicating that studies have shown benefits for heartstroke as well as diabetic patients, and that many experts are already discussing a low carb nutrition for diabetic patients who may then be able to live their lives without any insulin. Like any diet, the health effects will depend a great deal on the food choices one makes to meet the macronutrient requirements specified by the diet. 

Views critical of the diet

The Atkins diet has generally been considered by most medical and nutritional experts to be unsound or even quackery. Opponents of the diet mention that the initial weight loss upon starting on this diet is a phenomenon common with most diets, and is due to reduction in stored glycogen and related water in muscles, not fat loss. They claim that no evidence has surfaced that any diet will cause weight loss unless it reduces calories below the maintenance level. Reports have also indicated that successful weight loss due to the Atkins diet has been the result of fewer kilojoules (calories) being consumed by the dieter, rather than the lack of carbohydrates. [2]

Dr. Robert Eckel of the American Heart Association says that high-protein, low-carbohydrate diets put people at risk for heart disease. [3]

Another argument is that many countries whose traditional diets are high in carbohydrates and low in fat (for example, Japan) have significantly low rates of obesity. This seems to directly contradict Atkins' claims. 

Reference 
New England Journal of Medicine: (vol 348, p 2082) 

List of diets: South Beach Diet | Macrobiotic Diet | Paleolithic Diet | Vegetarian Diet | Fruitarian diet

Related articles:
Calories Count First! 
Carbohydrate Unloading: a Reality Check

This article is licensed under the GNU Free Documentation License (www.gnu.org/copyleft/fdl.html). It uses material from the Wikipedia article "Atkins Nutritional Approach" (en.wikipedia.org/wiki/Atkins_Nutritional_Approach).