The Atkins Diet represents a departure from prevailing theories. Atkins claimed there are two main unrecognized factors about Western eating habits, arguing firstly that the main cause of obesity is eating refined carbohydrates, particularly sugar, flour, and high-fructose corn syrups; and secondly, that saturated fat is overrated as a nutritional problem, and that only trans fats from sources such as hydrogenated oils need to be avoided. Consequently, Dr. Atkins rejected the advice of the food pyramid, instead asserting that the tremendous increase in refined carbohydrates is responsible for the rise in metabolic disorders of the 20th century, and that the focus on the detrimental effects of dietary fat has actually contributed to the obesity problem by increasing the proportion of insulin-inducing foods in the diet. While most of the emphasis in Atkins is on the diet, nutritional supplements and exercise are considered equally important elements.
Atkins involves the restriction of carbohydrates in order to switch the body's metabolism from burning glucose to burning stored body fat. This process (called lipolysis) begins when the body enters the state of ketosis as a consequence of running out of excess carbohydrates to burn. Dr. Atkins in his book New Diet Revolution claimed that the low-carb diet produces a "metabolic advantage" where the body burns more calories, overall, than on normal diets, and also expels some unused calories. He cited one study where he estimated this advantage to be 950 calories (4.0 MJ) a day.
Atkins restricts "net carbs", or carbs that have an effect on blood sugar. Net carbohydrates can be calculated from a food source by subtracting sugar alcohols and fiber (which are shown to have a negligible effect on blood sugar levels) from total carbohydrates. Sugar alcohols need to be treated with caution, because while they may be slower to convert to glucose, they can be a significant source of glycemic load and can stall weight loss. Fructose (eg, as found in many industrial sweeteners) also contributes to caloric intake, though outside of the glucose-insulin control loop.
Preferred foods in all categories are whole, unprocessed foods with a low glycemic load. Atkins Nutritionals, the company responsible for marketing the Atkins Diet, recommends that no more than 20% of calories eaten while on the diet come from saturated fat.
According to his book Atkins Diabetes Revolution, for people whose blood sugar is abnormally high or who have type-2 diabetes, this diet decreases or eliminates the need for drugs to treat these conditions. The Atkins Blood Sugar Control Program (ABSCP) is an individualized approach to weight control and permanent management of the risk factors for diabetes and cardiovascular disease.