Low Carb Diet Research

 Scientific research

 

    Main article: Medical research related to low-carbohydrate diets

 

Because of the substantial controversy regarding low-carbohydrate diets 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.

 

However, according to a review of the scientific data published in the Lancet, there is no proof that Atkins-style diets, are 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.

 

Other studies have shown possible short term benefits although the long term benefit remains unknown: 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 diabetes, cancer, and autism. The introduction of modern anticonvulsant drugs, however, substantially restricted its use. Interestingly, there has very recently been renewed interest in use of the diet, especially in children.

 

A study conducted in 1965 at the Oakland (California) Naval Hospital used a diet of 1000 calories per day, high in fat and limiting carbohydrates to 10 grams (40 calories) daily. Over a ten-day period, subjects on this diet lost more body fat than did a group who fasted completely. (Benoit et. al. 1965). Some subsequent studies have shown similar results. Many advocates of low-carbohydrate diets have termed this the metabolic advantage of such diets although many experts dispute whether this is truly a general phenomenon.

 

A recent study from Stanford University (2007) comparing Atkins (low-carb), Zone (moderately low-carb), LEARN (low in fat and high in carbohydrates), and Ornish (very high in carbohydrates and extremely low in fat) diets found that “of the more than 300 women in the study, those randomly assigned to follow the Atkins diet for a year not only lost more weight than the other participants, but also experienced the most benefits in terms of cholesterol and blood pressure.” “Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets (P<.05). Mean 12-month weight loss was as follows: Atkins, –4.7 kg (95% confidence interval [CI], –6.3 to –3.1 kg), Zone, –1.6 kg (95% CI, –2.8 to –0.4 kg), LEARN, –2.6 kg (–3.8 to –1.3 kg), and Ornish, –2.2 kg (–3.6 to –0.8 kg). Weight loss was not statistically different among the Zone, LEARN, and Ornish groups. At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups.” “The amount of weight loss at 12 months relative to baseline among all groups was modest at 2% to 5% . At the end of a year, the 77 women assigned to the Atkins group had lost an average of 10.4 pounds. Those assigned to LEARN lost 5.7 pounds, the Ornish followers lost 4.8 pounds and women on the Zone lost 3.5 pounds, on average. In all four groups, however, some participants lost up to 30 pounds. It could not be determined whether the benefits were attributable specifically to the low carbohydrate intake vs. other aspects of the diet.

 

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