Nature of the diet
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-carbohydrate 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. However, a review study in the Lancet (see below) concluded that there was no metabolic advantage and dieters were simply eating fewer calories due to boredom. Professor Astru stating that “The monotony and simplicity of the diet could inhibit appetite and food intake.”, or possibly protein inducing a satiating effect.
The Atkins diet restricts “net carbs” (carbohydrates that have an effect on blood sugar). The effect is to decrease the onset of hunger from low blood sugar. Dr. Atkins says in Dr. Atkins’ New Diet Revolution (2002) that hunger is the number one reason why low-fat diets fail. Though studies show the efficacy of the Atkins approach after one year is the same as a low-fat diet, Dr. Atkins claimed that it was easier to stay on the Atkins diet because dieters did not feel hungry or “deprived”. Other studies have sited that the ‘low fat’ trend which portrays the myth that fat in the food somehow transfers to fat in the body, do not mention the essential amino-acids which are essential in brain function and precursors to serotonin and other neurotransmitters. One study goes as far as comparing the low fat trend with the increase in diagnosed depression over the last two decades.
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 (e.g., 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.
Phases
There are four phases of the Atkins diet: induction, ongoing weight loss, pre-maintenance and lifetime maintenance.
Induction
The Induction phase is the first, and most restrictive, phase of the Atkins Nutritional Approach. It is intended to cause the body to quickly enter a state of ketosis. Carbohydrate intake is limited to 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 green vegetables (broccoli, green beans, spinach and asparagus). The allowed foods include a liberal amount of all meats, fish, shellfish, fowl, and eggs; up to 4 ounces (113 g) of soft or semi-soft cheese; salad vegetables; other low carbohydrate vegetables; and butter and vegetable oils. Drinking eight glasses of water per day is a must 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 is also recommended.
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.
Atkins suggests the use of Ketostix, small chemically reactive strips used by diabetics. These let the dieter monitor when they enter the ketosis or fat burning, phase. Other indicators of ketosis include a metallic taste in the mouth, or bad breath.
Ongoing weight loss
The Ongoing Weight Loss (OWL) phase of Atkins consists of an 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 goal in OWL is to find the “Critical Carbohydrate Level for Losing” and to learn in a controlled manner how food groups in increasing glycemic levels and foods within that group affect your craving control. The OWL phase lasts until weight is within 10 pounds (4.5 kg) of the target weight. During the first week, one should add more of the induction acceptable vegetables to his/her daily products. For example, 6-8 stalks of asparagus, salad, and one cup of cauliflower or one half of avocado. The next week, one should follow the carbohydrate ladder that Dr Atkins created for this phase and add fresh dairy. The ladder has 9 rungs and should be added in order given. One can skip a rung if one does not intend to include that food group in one’s permanent way of eating, such as the alcohol rung.
The rungs are as follows:
* Induction acceptable vegetables
* Fresh dairy
* Nuts
* Berries
* Alcohol
* Legumes
* Other fruits
* Starchy vegetables
* Grains
Pre-maintenance
Carbohydrate intake is increased again this time by 10 net carbs a week from the ladder groupings, and the key goal in this phase is to find the “Critical Carbohydrate Level for Maintenance”, this is the maximum number of carbohydrates you can eat each day without gaining weight. This may well be above the level of carbohydrates inducing ketosis on a testing stick. As a result, it is not necessary to maintain a positive ketosis test long term.
Lifetime maintenance
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.
Popularity
The Atkins Nutritional Approach gained widespread popularity in 2003 and 2004. At the height of its popularity one in eleven North-American adults were 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. Coca-Cola released C2 and Pepsi-Cola created Pepsi Edge, which was scheduled to be discontinued later in 2005. Unlike the sugar-free soft drinks Diet Coke and Diet Pepsi, which had been available for decades, these new drinks used a blend of traditional sweetener and the diet drinks’ artificial sweeteners to offset the allegedly inferior artificial sweetener flavor. These “half-and-half” drinks declined in popularity as soft drink makers learned to use newer sweeteners to mask the flavor of aspartame (or completely replace it) in reformulated diet drinks such as Coca-Cola Zero and Pepsi ONE.
Robert Atkins died from a fatal head injury sustained in a fall on ice in 2003. The nutritional plan suffered from rumors and allegations that he was obese at the time and had died from a heart condition as a result. 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 Low Carb Revolution was a one-hour documentary television special on the Atkins diet. The special, which aired on Food Network Canada, on April 25, 2004, described how this diet works, had success stories, and quickly presented some recipes.
Scientific Studies
Several randomized, controlled studies of less than one year, published in peer-reviewed journals, have been conducted to gauge the effectiveness of the Atkins diet. There are no rigorous studies to show the results after 1 year.
According to a review of the scientific data published in the Lancet, there is no proof that the Atkins diet is effective beyond 6 months. The review led by Arne Astrup of the Centre of Advanced Food Research at Copenhagen’s RVA University, concluded that “There is no clear evidence that Atkins-style diets are better than any others for helping people to stay slim,[and] despite the popularity and apparent success of the Atkins diet, evidence in support of its use lags behind. Although the diet appears as claimed to promote weight loss without hunger at least in the short-term, the long-term effects on health and disease prevention are unknown.”
The researchers concluded it was unlikely that weight-loss come through ketosis because ‘urinary traces of ketones were so low that very little energy would be used up this way’. They concluded that a possible reason that participants lost weight was that the diet was so monotonous that they simply ate less; weight loss was a result of boredom. “Patients who want to try these diets should be told that, although safety cannot be guaranteed, they seem to be safe for short-term use (up to six months) as long as weight loss occurs,” the authors said.
When the Atkins diet was introduced in the 1970s, it was immediately attacked by existing experts, who claimed it was unhealthy and would fail. For example, Atkins testified before the Senate Select Committee on Nutrition and Human Needs, in April, 1973. That day, “three authorities in nutrition and health … [testified] that Atkins’s severely carbohydrate-restricted diet was neither revolutionary, effective, nor safe,” and a comment by Harvard nutritionist Fred Stare was read into the record: “The Atkins diet is nonsense…. Any book that recommends unlimited amounts of meat, butter and eggs, as this does, in my opinion is dangerous. The author who makes the suggestion is guilty of malpractice.” Subsequent studies have not supported those fears for the short term, but the long term safety remains unknown.
* “The low-carbohydrate diet produced a greater weight loss for the first six months, but the differences were not significant at one year. The low-carbohydrate diet was associated with a greater improvement in some risk factors for coronary heart disease. Adherence was poor and attrition was high in both groups. Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate, high-protein, and high-fat diets.” — New England Journal of Medicine, Volume 348, Pages 2082-2090, 22 May 2003, Number 21
* A study comparing weight loss and metabolic changes in obese adults randomly assigned to either a low-carbohydrate diet or a conventional weight loss diet at the Philadelphia Veterans Affairs Medical Center concluded the following: “Participants on a low-carbohydrate diet had more favorable overall outcomes at 1 year than did those on a conventional diet. Weight loss was similar between groups, but effects on atherogenic dyslipidemia and glycemic control were still more favorable with a low-carbohydrate diet after adjustment for differences in weight loss.”
* In a controlled study, published in JAMA (March 7, 2007), by Gardner at Stanford University, found ‘Weight loss was not statistically different among the Zone, LEARN, and Ornish groups’ but ‘was significantly different between the Atkins and Zone diets’. The study followed 311 premenopausal, nondiabetic women, age 25-50. The women lost more weight (mean 4.7 kg equating to 0.2lbs(90g)/week) on the Atkins diet than on 3 higher-carbohydrate diets (LEARN 2.6 kg, Ornish 2.2 kg, and Zone 1.6 kg), without increasing cardiovascular risks. The statistically significant findings for changes in HDL cholesterol, triglycerides, and systolic blood pressure favored Atkins over the other three diets. The authors conclude: “Concerns about adverse metabolic effects of the Atkins diet were not substantiated within the 12-month study period.”
The strongest evidence is randomized, controlled studies published in peer-reviewed journals. The greater the number of subjects, and the longer the subjects are followed, the more powerful the study. To date, the longest studies are 1 year, so the effects of the diet over longer durations are not known.
The medical principles and scientific theory behind the Atkins diet were first put forward in a series of articles by Dr. Richard D. Feinman, a professor of biochemistry and medical researcher at State University of New York (SUNY) Health Science Center (Downstate) at Brooklyn. Feinman, president of the Nutrition & Metabolism Society, published work which attempts to prove the common idea that “a calorie is a calorie” is not correct. His research aims to demonstrate why the diet is nutritionally sound and to elucidate principles which prove Atkins scientifically correct.
Proponents of the Atkins diet feel much of the criticism leveled at the diet comes from statements and opinions of individuals and associations, rather than from controlled and reviewed studies. Advocates of the diet dispute criticisms, such as the fact that a low-carbohydrate diet is likely to be high-fat and allegations that fat, especially saturated fat, is harmful. Atkins backers maintain that, unlike trans fat, which can result from partial hydrogenation, fully saturated fat is not harmful. Proponents cite the award-winning science writer Gary Taubes who, in a 2001 article in Science, 291 (5513): 2536 claimed that the oft-cited “consensus” opinion against saturated fats derives from political rather than scientific motives. Taubes’ 2007 book Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease also makes this point, but in more depth. Taubes reviews the nutrition research of a century from various angles, and draws his conclusion from a very diverse set of evidence.
One study found that saturated fat may be cardio-protective in post menopausal women.
The May 22, 2003, issue of the New England Journal of Medicine published two scientific, randomized studies comparing standard low-fat diets to low-carbohydrate diets such as the Atkins Diet. In both studies, subjects lost more weight on the low-carbohydrate plans at 6-months but not at 1-year. The editors noted that “Adherence was poor and attrition was high in both groups. Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate, high-protein, and high-fat diets.”
Duke University, funded by an unrestricted grant from the Atkins Foundation, (2005) found that both the low-carbohydrate and low-fat diets studied improved cardiac health indicators, but in different ways. The commonality between the diets studied is that both restricted refined sugar and junk food and both encouraged 30 minutes of exercise at least three times a week.
Controversies
An analysis conducted by Forbes magazine found that the boxed retail Atkins Nutritional Approach food product is one of the top five in the expense category of ten plans Forbes analyzed. The analysis showed the median average of the ten diets was approximately 50% higher, and Atkins 80% higher, than the American national average. Atkins was less expensive than Jenny Craig 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).
But many in the scientific community also raise serious concerns:
* Dr. Robert Eckel of the American Heart Association says that high-protein, low-carbohydrate diets put people at risk of heart disease; A long term study published in the New England Journal of Medicine in 2006 found that women reduced heart disease risk by eating more protein and fat from vegetable sources.
* A 2001 scientific review conducted by Freedman et al. and published in the peer reviewed scientific journal Obesity Research concluded that low-carb dieters’ initial advantage in weight loss was a result of increased water loss, and that after the initial period, low-carbohydrate diets produce similar fat loss to other diets with similar caloric intake.
* The May 2004 Annals of Internal Medicine study showed that “minor adverse effects” of diarrhea, general weakness, rashes and muscle cramps “were more frequent in the low-carbohydrate diet group”.
* Consuming too much protein can create health problems and protein toxicity for patients with certain medical problems, for example those with preexisting kidney problems.
Opponents of the diet also point out that the initial weight loss upon starting the 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 food energy (calories) below the maintenance level and that weight loss from the Atkins diet may be the result of less food energy being consumed by the dieter, rather than the lack of carbohydrates. They further point out that weight loss on fad diets, which typically restrict or prohibit certain foods, is often because the dieter has fewer food choices available.
Misconceptions about the diet
Many people incorrectly believe that the Atkins Diet promotes eating unlimited amounts of fatty meats and cheeses. This is a key point of clarification that Dr. Atkins addressed in the more recent revisions of his book. Although the Atkins Diet does not impose limits on certain foods, or caloric restriction in general, Dr. Atkins points out in his book that this plan is “not a license to gorge.” The director of research and education for Atkins Nutritionals, Collette Heimowitz, has said, “The media and opponents of Atkins often sensationalize and simplify the diet as the all-the-steak-you-can-eat diet. This has never been true.”
Another common misconception arises from confusion between the Induction Phase and rest of the diet. The first two weeks of the Atkins Diet are strict, with only 20g of carbohydrates permitted per day. 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. Once the weight-loss goal is reached, carbohydrate levels are raised gradually, though still significantly below USDA norms, and still within or slightly above the definition of ketosis.
The Induction Phase is also known for its comparatively lower intake of dietary fiber, and this is often misconstrued as characteristic of the diet as a whole. In fact fiber supplements, such as psyllium seed husks, are recommended for the early stages. It is often misstated that those on the diet do not consume enough vegetables and fruits. However those who follow it properly should not face this problem as even the Induction Phase allows for adequate amounts of dark green leaf vegetables.
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