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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.
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 Atkins 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 induces 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 ) 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 a metabolic advantage because "burning fat takes more calories so you expend more calories". He cited one study where he estimated this advantage to be 950 Calories (4.0 MJ) per day. A review study published in Lancet concluded that there was no such metabolic advantage and dieters were simply eating fewer calories due to boredom. Professor Astrup stated, "The monotony and simplicity of the diet could inhibit appetite and food intake".
In the most recent book by Drs. Westman, Phinney, and Volek, the authors suggest optimal levels of protein, fat, and calorie intake, and have moved away from the metabolic advantage theory.
The Atkins Diet restricts "net carbs" (digestible carbohydrate grams that affect blood sugar less fiber grams). One effect is a tendency to decrease the onset of hunger, perhaps because of longer duration of digestion (fats and proteins take longer to digest than carbohydrates). Atkins states in his 2002 book New Diet Revolution that hunger is the number one reason that low-fat diets fail, and that the Atkins diet is easier because one is satisfied with adequate protein, fat and fiber.
Net carbohydrates can be calculated from a food source by subtracting fiber and sugar alcohols (which are shown to have a smaller effect on blood sugar levels) from total carbohydrates. Sugar alcohols contain about two calories per gram, and the American Diabetes Association recommends that diabetics count each gram as half a gram of carbohydrate. Fructose (for example, as found in many industrial sweeteners) has four calories per gram but has a very low glycemic index and does not cause insulin production, probably because β cells have low levels of GLUT5. Leptin, an appetite regulating hormone, is however not triggered following consumption of fructose. This may for some create an unsatisfying feeling after consumption which might promote binge behavior that culminates in an increased blood triglyceride level arising from fructose conversion by the liver.
Preferred foods in all categories are whole, unprocessed foods with a low glycemic index, although restrictions for low glycemic carbohydrates (black rice, vegetables, etc.) are the same as those for high glycemic carbohydrates (sugar, white bread). Atkins Nutritionals, the company formed to market foods that work with the Atkins Diet, recommends that no more than 20% of calories eaten while on the diet come from saturated fat.
Atkins' book, Atkins Diabetes Revolution, states that, for people whose blood sugar is abnormally high or who have Type 2 diabetes mellitus, the Atkins 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. Nevertheless, the causes of Type 2 diabetes remain obscure, and the Atkins Diet is not accepted in conventional therapy for diabetes.
|This article may be too technical for most readers to understand. (August 2012)|
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. 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. 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 oxidized and give acetyl-CoA that enters the Krebs cycle directly. 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.
The effects of the Atkins diet remain a subject of much debate. Some studies conclude that the Atkins diet helps prevent cardiovascular disease, lowers the low density lipoprotein (LDL) cholesterol, and increases the amount of HDL, or so-called "good" cholesterol. Some studies suggest that the diet could contribute to osteoporosis and kidney stones. A University of Maryland study, in which test subjects were given calorie increases whenever their weight started to drop, showed higher LDL cholesterol and markers for inflammation.
According to Harper (2004) in a year-long study, the concentration of high-density lipoprotein (HDL) cholesterol increased, and insulin resistance improved much more in dieters following the Atkins diet than in those following a low-fat, calorie restricted diet. Harper also mentions that there had not been enough prior research to allow him to confidently say that Atkins is safe to be recommended to patients.
A 2005 study by Beisswenger and colleagues compared levels of the glycotoxin methylglyoxal (MG) before and after starting the Atkins diet. MG is associated with blood vessel and tissue damage, and is higher in people with poorly controlled diabetes. The study found that MG levels doubled shortly after the diet was started, noting that the MG rise was related to the presence of ketosis. A rise in acetol and acetone was found, indicating that MG was produced by oxidation. MG also arose as a by-product of triglyceride breakdown and from lipoxidation (ketosis related to fat intake).
Whether or not increased methylglyoxal is harmful to human beings has been questioned by the Indian Association for the Cultivation of Science, who in a 2008 critical overview of various studies (including Beisswenger's study) state, "The authors present a brief critical overview of studies indicating both toxic and beneficial effects of methylglyoxal and suggest that the beneficial effects of methylglyoxal outweigh its toxic effects". While not drawing any definite conclusions, the Indian Association for the Cultivation of Science recommends further study especially in the area of using methylglyoxal to cure or treat cancer.
There are four phases of the Atkins diet: induction, ongoing weight loss, pre-maintenance and lifetime maintenance.
Induction is the most restrictive phase of the Atkins Nutritional Approach. Two weeks are recommended for this phase. It is intended to cause the body to quickly enter a state of ketosis. Carbohydrate intake is limited to less than 20 net grams per day (grams of carbohydrates minus grams of fiber, sugar alcohols, or glycerin), 12 to 15 net grams of which must come in the form of salad greens and other fruits and vegetables such as broccoli, spinach, pumpkin, cauliflower, turnips, tomatoes, and asparagus, to name a few of the 54 allowed by Atkins (but not legumes, since they are too starchy for the induction phase). The allowed foods include 4 to 6 ounces per meal of all meats, poultry, fish, shellfish, fowl, and eggs; up to 4 ounces (113 g) of hard or semi-soft cheese such as cheddar cheese; most salad vegetables; other low carbohydrate vegetables; and butter, olive oil and vegetable oils. Drinking eight glasses of water per day is a requirement during this phase. Alcoholic beverages are not allowed during this phase. Caffeine is allowed in moderation so long as it does not cause cravings or low blood sugar. If a caffeine addiction is evident, it is best to not allow it until later phases of the diet. A daily multivitamin with minerals, except iron, is also recommended. A normal amount of food, on Induction, is around 20 grams of naturally occurring sugars from vegetables (or net carb), at least 100 grams of fat, and about 18 ounces of protein or 150 grams.
The Induction phase is usually when many see the most significant weight loss — reports of losses of 5 to 10 pounds per week are not uncommon when Induction is combined with daily exercise. Many Atkins followers make use of Ketostix, small chemically reactive strips used by diabetics, but current recommendations discourage use due to inaccurate readings. These let the dieter monitor when they enter the ketosis, or fat burning phase, but are not always accurate for non-diabetic users. Other indicators of ketosis include a metallic taste in the mouth, or the sweet smell of ketones on breath or sweat.
The Ongoing Weight Loss (OWL) phase of Atkins consists of small, incremental increase in carbohydrate intake, but remaining at levels where weight loss occurs. The target daily carbohydrate intake increases each week by 5 net grams, a very low amount of carbohydrate. A goal in "ongoing" phase is to find the "Critical Carbohydrate Level for Losing" for the individual and to determine which foods an individual may incorporate without triggering cravings. This phase of the Atkins' diet lasts until weight is within 10 pounds (4.5 kg) of the target weight.
During the first week of Ongoing Weight Loss, Atkins dieters are instructed to add a small serving of nuts or seeds. The next week, one should follow the "carbohydrate ladder" and add berries. The ladder has 9 rungs and should be added in the following order. One can skip a rung if one does not intend to include that food group in one's permanent way of eating. The rungs for legumes, high carbohydrate fruits, starchy vegetables, and whole grains are not added until the maintenance phase. They are then incorporated in modest amounts.
The rungs are as follows:
Alcohol is also permitted, but is no longer a specific rung of the ladder. Low-carbohydrate drinks such as spirits and dry wines are preferred, and must of course be included in the daily allowance.
Daily net carbohydrates intake is increased again this time by 10 grams each week from the latter groupings, and the key goal in this phase is to find the "Critical Carbohydrate Level for Maintenance". This is the maximum number of carbohydrates a dieter can eat each day without gaining weight. This may well be above the level of carbohydrates that induce ketosis on a testing stick. As a result, it is not necessary to maintain a positive ketosis test long term.
Dieters may be able to add some of the forbidden carbs back into their diet once a week. In this phase, according to the Atkins diet, one's body is beginning to lose the protection of ketosis as one prepares for the last phase which is Lifetime Maintenance.
Dieters are encouraged to continue to drink at least eight glasses of water per day and to increase their daily carbohydrate count by 10 grams each week as long as they continue to lose weight. The Atkins plan recommends that once dieters reach their goal weight and are able to maintain that level for a month or so, then they can increase their daily carb consumption by another 10 grams to see if that is possible without gaining. If one gains weight at that level, the plan recommends that one drops back levels of carbohydrates in 10 grams increments. It may take several weeks to find one's individual tipping point.
This phase is intended to carry on the habits acquired in the previous phases, and avoid the common end-of-diet mindset that can return people to their previous habits and previous weight. Whole, unprocessed food choices are emphasized, with the option to drop back to an earlier phase if you begin to gain weight.
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. 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. 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 sustained in a fall on ice.
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. The company continues to operate and the diet plan remains popular, although it has not regained its former popularity.
Because of substantial controversy regarding the Atkins Diet and even disagreements in interpreting the results of specific studies it is difficult to objectively summarize the research in a way that reflects scientific consensus. Although there has been some research done throughout the twentieth century, most directly relevant scientific studies, both those that directly analyze the Atkins Diet and those that analyze similar diets, have occurred in the 1990s and early 2000s and, as such, are relatively new. Researchers and other experts have published articles and studies that run the gamut from promoting the safety and efficacy of the diet, to questioning its long-term validity, to outright condemning it as dangerous. A significant early criticism of the Atkins Diet was that there were no studies that evaluated the effects of Atkins beyond a few months. However, studies began emerging in the mid-to-late-2000s which evaluate low-carbohydrate diets over much longer periods, controlled studies as long as two years and survey studies as long as two decades.
In addition to research on the efficacy of Atkins and other low-carbohydrate diets, some research has directly addressed other areas of health affected by low-carbohydrate diets. For example, contrary to popular belief that low-carbohydrate diets damage the heart, one study found that women eating low-carbohydrate, high-fat/protein diets had the same or slightly less risk of coronary heart disease, compared to women eating high-carbohydrate, low-fat diets. Other studies have found possible benefits to individuals with type 2 diabetes, cancer, and epilepsy. One study comparing two levels of low-carbohydrate diets (ketogenic—the lowest carbohydrate level—and non-ketogenic) found that both had positive effects in terms of insulin sensitivity, weight loss, and fat loss while the ketogenic diet showed slightly higher risks of inflammation and somewhat lower perceived levels of vigor, described as "potentially harmful metabolic and emotional side-effects" (although it should be noted that one of the researchers of this study, Barry Sears, markets The Zone as a competing low-carbohydrate diet).
A 2007 study done at Stanford University Medical School, The A to Z Weight Loss Study, compared the Atkins diet with the Zone, Ornish, and LEARN diets in a randomized group of 311 obese premenopausal women over a period of 12 months. The study found that weight loss was significantly higher for the Atkins diet compared to the other three diets. Secondary factors such as HDL-C, triglyceride levels, and systolic blood pressure were also found to have improved to healthier levels compared to the other diets.
A 2012 study done at Boston Children's Hospital compared a very low carbohydrate diet (the Atkins diet) with a low fat, high carbohydrate diet, and a low glycemic index diet. Reduction of the resting metabolic rate as a result of dieting, a key factor in the failures of dieting, was the least in the very low carbohydrate diet. In addition, measured total energy expenditure in the patients was the highest in the very low carbohydrate diet, suggesting that a very low carbohydrate diet would be the most likely to produce a sustained weight loss. A possible negative side effect was that C-Reactive Protein levels, a marker for possible future cardiovascular disease, trended somewhat higher in the very low carbohydrate diet.
In January 2004, the BBC Two science program Horizon broadcast the results of experiments comparing Atkins to other diets. Dr. Joe Millward of the University of Surrey, who headed up the research, concluded that the Atkins dieters lost weight because they were eating less calories, just as people on low-fat diets do. The program also attributed Atkins weight loss to the fact that carbohydrates are the least filling food. Professor Arne Astrup, of the Royal Veterinary & Agricultural University in Copenhagen, conducted a study comparing a group of people on a high protein diet to another group on a high carbohydrate diet. According to Astrup, the group eating more protein lost significantly more weight because protein is more easily filling, and thus members of that group consumed fewer calories, even though they had free access to whatever food they wanted.
An analysis conducted by Forbes magazine found that the sample menu from the Atkins Nutritional Approach is one of the top five in the expense category of ten plans Forbes analyzed. This was due to the inclusion of recipes with some high cost ingredients such as lobster tails which were put in the book to demonstrate the variety of foods which could be consumed on the diet. The analysis showed the median average of the ten diets was approximately 50% higher, and Atkins 80% higher, than the American national average. The Atkins diet was less expensive than the Jenny Craig diet and more expensive than Weight Watchers.
Low-carbohydrate diets have been the subject of heated debate in medical circles for three decades. They are still controversial and only recently has any serious research supported some aspects of Atkins' claims, especially for short-term weight-loss (6 months or less). In a comparison study by Dansinger and colleagues (2005), the goal was to compare popular diets like Atkins, Ornish, Weight Watchers, and Zone for the amount of weight lost and a heart disease risk reduction. In the study there were 247 individuals and it lasted for 1 year. All the subjects were overweight at baseline, and had an increased risk for cardiac diseases. One of the diets was assigned to each person.
The Atkins diet group ate 20g of CHO (carbohydrate) a day, with a gradual increase toward 50 g daily. But according to Table 2 of the study, increased to well over 130g after the second month and up to 190g by the sixth month. At this point, the Atkins diet group were eating carbohydrates equivalent to the other three groups. The Zone group ate a 40-30-30 % diet of carbohydrates, fats and proteins respectively. The Weight Watchers group was to keep the “points” of their food in a determined range, based on their weight. The Ornish group ate a vegetarian diet with 10% of calories coming from fats. The weight, waist size, blood pressure, and a blood sample were taken, at the beginning, after 2 months, 6 months and 12 months. All four diets resulted in weight loss with no significant difference between the diets.
But many in the scientific community also raise serious concerns:
Many people believe that the Atkins Diet promotes eating unlimited amounts of fatty meats and cheeses. This was allowed and promoted in early editions of the book. In the newest revision, not written by the now deceased Dr. Atkins, this is not promoted. The Atkins Diet does not impose caloric restriction, or definite limits on proteins, with Atkins saying in his book that this plan is "not a license to gorge," but rather that eating protein until satiated is promoted. The director of research and education for Atkins Nutritionals, Collette Heimowitz, has said, "The media and opponents of Atkins often sensationalise and simplify the diet as the all-the-steak-you-can-eat diet. This has never been true". However, this new approach by Atkins Nutritionals is often at odds with the earlier writings of Dr. Atkins.
A common misconception arises from confusion between the Induction Phase and rest of the diet. The rules for the induction phase have changed since the first printing of Atkin's Diet Revolution, in which all carbohydrates were counted the same. Today's version of the diet differentiates between carbohydrates, and counts only "net carbs" toward the daily total. The first two weeks of the Atkins Diet are strict, with only 20g of 'net' carbohydrates permitted per day. The Net Carbs number reflects the grams of carbohydrate that are said to significantly impact blood sugar level, and therefore, sugar alcohol carbs are not counted and neither are those in fiber when doing the newer version of the Atkins plan.
Atkins states that a dieter can safely stay at the Induction Phase for several months if the person has a lot of weight to lose. Induction, however, is merely a stage to get the body used to fat, and cure cravings for high carbohydrate foods. Gradually, through the stages of the eating plan, carbohydrate levels are raised, though carbs are still significantly below USDA norms. Once the weight-loss goal is reached, carbohydrate levels are raised again to a state of equilibrium where no weight is lost or gained, which may or may not be below USDA norms, depending on the individual's metabolism, age, and their exercise level.
Dr. Eric Westman, director of the Duke University's Lifestyle Medicine Clinic and co-author of The New Atkins for a New You, believes low-carb or Atkins should be viable options among diets.
"The Atkins diet was labeled as a high-fat diet," Westman said in an interview with The New York Times. "We've been told over the past 40 years that fat in the diet is bad. Now we know that fat is not bad. What's happened is that there is a paradigm shift in thinking about carbohydrates, fat and protein and health."
Atkins Nutritionals, Inc. (ANI) was founded in 1989 by Atkins to promote the sale of Atkins-branded products. Following his death, waning popularity of the diet and a reduction in demand for Atkins products, Atkins Nutritionals, Inc. filed for Chapter 11 bankruptcy protection on July 31, 2005 citing losses of $340 million. The company emerged from bankruptcy on January 10, 2006, introducing "a new business strategy that focuses on providing great-tasting portable foods with a unique nutrition advantage to healthy, active men and women." Although the marketing focus has changed, the products are still low-carb. It is also stated on the packages the stage of the Atkins Nutritional Approach where they may be used.
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