Tag: the Atkins Nutritional Approach

the Atkins Nutritional Approach

The Atkins Diet, officially called the Atkins Nutritional Approach, is a low-carbohydrate diet promoted by Robert Atkins from a research paper he read in The Journal of the American Medical Association published by Alfred W. Pennington, titled “Weight Reduction”, published in 1958.[1]

Atkins used the study to resolve his own overweight condition. He later popularized the method in a series of books, starting with Dr. Atkins’ Diet Revolution in 1972. In his second book, Dr. Atkins’ New Diet Revolution (2002), he modified parts of the diet but did not alter the original concepts.

The New Atkins for a New You (2010) is based upon a broad array of information gained over the last decade not covered in previous editions, including nutrient-rich foods. The New Atkins for a New You Cookbook was released in 2011 by Colette Heimowitz to provide dieters with simple, low-carb recipes.

The diet involves limited consumption of carbohydrates to switch the body’s metabolism from metabolizing glucose as energy over to converting stored body fat to energy. This process, called ketosis, begins when insulin levels are low; in normal humans, insulin is lowest when blood glucose levels are low (mostly before eating). Reduced insulin levels induce lipolysis, which consumes fat to produce ketone bodies. On the other hand, caloric carbohydrates (for example, glucose or starch, the latter made of chains of glucose) affect the body by increasing blood sugar after consumption (in the treatment of diabetes, blood sugar levels are used.[2]) Fiber, because of its low digestibility, provides little or no food energy and does not significantly affect glucose and insulin levels.

In his early books such as Dr Atkins’ New Diet Revolution, Atkins made the controversial argument that the low-carbohydrate diet produces ametabolic advantage because “burning fat takes more calories so you expend more calories”.[3] He cited one study where he estimated this advantage to be 950 Calories (4.0 MJ) per day. A review study published in Lancet[4] concluded that there was no such metabolic advantage and dieters were simply eating fewer calories due to boredom. Astrup stated, “The monotony and simplicity of the diet could inhibit appetite and food intake”.

The initial stage of the Atkins Diet is referred to as the induction phase and is considered a ketogenic diet. In ketogenic diets there is production of ketones that contribute to the energy production in the Krebs cycle.[11] Ketogenic diets rely on the insulin response to blood glucose. Insulin is a hormone produced by beta-cells in the pancreas in response to high levels of blood glucose (i.e. after digestion of a carbohydrate meal). The main function of insulin is to shuttle glucose from the blood to peripheral tissues, where they will be needed for fuel or stored as fat. Thus, insulin is a regulator of blood glucose that is too high.

Because ketogenic dieters eat few carbohydrates, there is no glucose that can trigger the insulin response. Therefore, the body must seek an alternate fuel source to fulfill its metabolic needs. During this diet, the main sources of fuel for human cells (glucose) is now at less than adequate supply, cells must take alternate steps to convert stored fuel to glucose. Other than carbohydrate ingestion (which is directly converted into glucose and then immediately available for use as fuel when it enters the blood), the cells must rely on glucose production from conversion of either protein (amino acids) or stored fat.

When blood levels of glucose are low, regulating hormones are released to signal for the need to elevate blood sugar. This is in contrast to the actions of insulin. Since the body is less able to compensate for a state of hypoglycemia, than it is for hyperglycemia, hormones (growth hormone, epinepherine, cortisol, and glucagon) are released causing a cascade resulting in glycogen release from the liver and adipose(fat) cell conversion of triacylglycerol to fatty acids.

Blood glucose levels have to decrease to less than 3.58 mmol/L (64.5 mg/dl) for growth hormone, epinephrine, and glucagon to be released to maintain energy metabolism.[11] In the adipose cells, growth hormone and epinephrine initiate the triacylglycerol to be broken down to fatty acids. These fatty acids go to the liver and muscle where they should be oxidizedand give acetyl-CoA that enters the Krebs cycle directly.[11] However, the excess acetyl-CoA in the liver is converted to ketones (ketone bodies), that are transported to other tissues. In these tissues they are converted back into acetyl-CoA in order to enter the Krebs cycle. Glucagon is produced when blood glucose is too low, and it causes the liver to start breaking glycogen into glucose. Since the dieter does not eat any more carbohydrates, there is no glycogen in the liver to be broken down, so the liver converts fats into free fatty acids and ketone bodies, and this process is called ketosis. Because of this, the body is forced to use fats as a primary fuel source.[11]

The Atkins Nutritional Approach gained widespread popularity in 2003 and 2004. At the height of its popularity one in eleven North American adults was on the diet.[19] This large following was blamed for large declines in the sales of carbohydrate-heavy foods like pasta and rice: sales were down 8.2 and 4.6 percent, respectively, in 2003. The diet’s success was even blamed for a decline in Krispy Kreme sales.[20] Trying to capitalize on the “low-carb craze,” many companies released special product lines that were low in carbohydrates.

In 2003, Atkins died from a fatal head injury due to a fall on ice,[21] and while he had a history of heart disease, Mrs. Atkins was quoted as stating that the circumstances of his death from an epidural hematoma had nothing to do with his diet or history of viral cardiomyopathy.[22][23]

On July 31, 2005, the Atkins Nutritional company filed for Chapter 11 bankruptcy protection after the percentage of adults on the diet declined to two percent and sales of Atkins brand product fell steeply in the second half of 2004.[24] The company continues to operate and the diet plan remains popular, although it has not regained its former popularity

External links

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