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Atkins Nutritional Approach
From Wikipedia, the free encyclopedia
The Atkins Nutritional Approach, popularly known as the Atkins Diet or just Atkins, is the most marketed
and well-known low-carbohydrate diet. It was adapted by Dr. Robert Atkins in the 1960s from a diet he read in
the Journal of the American Medical Association and utilized to resolve his own overweight condition
following medical school and graduate medical training.
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.
Atkins restricts "net carbs", or carbohydrates 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.[1]
Controversy
It is a common misconception that meat with high fat is a typical meal in the Atkins diet. The actual goal of
Atkins dieters is to avoid high glycemic index foods such as soft drinks, fruit juice and potatoes. Atkins dieters
can still eat a variety of food such as salads, cheese, and lean meats.
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:
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Dr. Robert Eckel of the American Heart Association says that high-protein, low-carbohydrate diets put
people at risk of heart disease [4]; A long term study published in the New England Journal of Medicine
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in 2006 found that women reduced heart disease risk by eating more protein and fat from vegetable
sources.[5]
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.[6]
The May 2004 Annals of Internal Medicine study showed that Atkins Dieters had significantly more
diarrhea, general weakness, rashes and muscle cramps. Atkins.com now suggests a fiber supplement.
Consuming too much protein can create health problems and protein toxicity for patients with certain
medical problems,[1] 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 reports have indicated that successful weight loss due to the Atkins diet may
be the result of less food energy being consumed by the dieter, rather than the lack of carbohydrates. [7] They
further point out that weight loss on fad diets, which typically restrict or prohibit certain foods, is often due to
the fact that the dieter has fewer food choices available.
Evidence in favor of the diet
Several randomized, controlled studies, published in peer-reviewed journals, have concluded that dieters on the
Atkins diet have achieved weight loss comparable to or greater than other diets, up to 1 year. Blood fats have
also improved, and no serious adverse effects have been observed. There are no rigorous studies to show the
results after 1 year.
In the largest, most recent randomized, controlled study, published in JAMA (March 7, 2007), by Gardner at
Stanford University, women "lost more weight and experienced more favorable overall metabolic effects at 12
months" than in other diets. The study followed 311 premenopausal, nondiabetic women, age 25-50. The
women lost significantly more weight (mean 4.7 kg) 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. Changes in HDL
cholesterol, triglycerides, and mean blood pressure significantly 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."[9]
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, or 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."[10] Subsequent studies have not supported those fears:
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"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 lowcarbohydrate, high-protein, 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 lowcarbohydrate diet after adjustment for differences in weight loss." [11]
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"sustained weight loss [at 6 months]" — Atkins funded, non-randomized, non-control intervention trial,
American Journal of Medicine, Volume 113, Issue 1, July 2002, Pages 30-36.
A 2-week study on studying restricted carbohydrate intake in 10 obese patients with type 2 diabetes
concluded: "In a small group of obese patients with type 2 diabetes, a low-carbohydrate diet followed
for 2 weeks resulted in spontaneous reduction in energy intake to a level appropriate to their height;
weight loss that was completely accounted for by reduced caloric intake; much improved 24-hour blood
glucose profiles, insulin sensitivity, and hemoglobin A1c; and decreased plasma triglyceride and
cholesterol levels. The long-term effects of this diet, however, remain uncertain." This was not a
controlled study in that there was no control group; it merely observed the effect of putting ten obese
diabetics on a carbohydrate restricted diet - not specifically the Atkins diet. [12]
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 explained 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.[13]
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.
Critics of the Atkins diet may focus particularly on Atkins, or on low-carbohydrate dieting in general.
Proponents claim that critics fail to consider that people are built differently, and as with any diet, the Atkins
Nutritional Approach may not be effective for some people.
Continuing research supports the idea that saturated fat may be cardio-protective in some populations.[14][15]
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, high-fat diets."[16]
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%. This counters one of the chief criticisms of
Atkins' approach, which is that cholesterol is raised by eating fatty foods and meat.
In another study, conventional dieters' HDL cholesterol raised by 1.6% while their triglyceride levels improved.
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).[16] The study followed
the diets of 63 obese men and women. (See New Scientist, 21 May 2003.)