The latest group to voice concerns about the safety of the diet system is a coalition of consumer, nutrition and public health groups called the Partnership for Essential Nutrition. Among the claims made by the group - backed, its members claim, by an increasingly broad body of scientific evidence - are that low-carb diets are unlikely to lead to sustained long term weight loss and could in fact increase the risk for a number of life-threatening medical conditions.
The coalition's claims echo those reported earlier this month by FoodandDrinkEurope.com from the Flour Advisory Bureau and other bakery-related organisations that the 'science' behind the low-carb diets was flawed and potentially extremely dangerous.
Basing its claims on the findings of a comprehensive review of the scientific literature, the coalition said that that losing weight on extreme low-carb diets such as Atkins could lead to serious health problems like kidney stress, liver disorders and gout. The diets could also increase the risk of coronary heart disease, diabetes, stroke and several types of cancer, it added.
Moreover, the coalition identified a number of short-term side effects from low-carbohydrate diets that, although less serious, could affect quality of life. These include severe constipation, gastrointestinal problems, nausea, repeated headaches, difficulty in concentrating and the loss of energy.
"Low carbohydrate diets conflict with decades of solid scientific research that clearly encourages us to reduce saturated fat and boost fruit, vegetable and fibre intake," said Barbara J. Moore, president and CEO of Shape Up America!, which founded the coalition.
"Restricting carbohydrates stresses vital organs and alters brain metabolism while offering no advantages in terms of either fat loss or long-term weight control."
The 11 members of the coalition are drawn from consumer, nutrition and public health organisations and include the American Institute for Cancer Research, the American Obesity Association and the National Consumers League.
The coalition's review also questions the effectiveness of extreme low-carbohydrate diets for sustained weight loss. Summarising recent scientific studies that found the rapid weight loss associated with these diets was temporary and often resulted in yo-yo dieting (putting weight back on immediately after coming off the diet, requiring a new period of dieting), the coalition voiced apprehension about the processes by which people lose weight on these diets.
Like the UK organisations before it, the coalition also took aim at the proliferation of low-carb diet products which it suggested were profiting from consumers' ignorance. Food and beverage products labelled as 'low-carb', 'reduced carb', 'carbohydrate-free', 'carb aware', 'carb smart' or 'carb countdown' are not regulated by the Food and Drug Administration (FDA), the coalition said, adding that US consumers now spend an average of $85 a month on these products.
A recent survey of American dietary habits suggested that 19 per cent of adults who are trying to lose weight are doing so primarily by reducing the amount of carbohydrates they consume, in turn increasing their consumption of other products - a far cry from the balanced diet recommended by nutritionists.
More worryingly, according to the coalition's members, is the revelation that the hype over low-carb foods is also affecting the rest of the US population, many of whom are now consuming fewer fruits, vegetables, whole grains and low-fat dairy products.
"Compared to the five servings a day of fibre-rich fruits and vegetables recommended by the National Cancer Institute, the survey finds 68 per cent now eat two or less servings of fruit a day and 63 per cent consume two or less servings of vegetables. Moreover, 71 per cent of the public consumes less than the three recommended daily servings of low-fat dairy products while 15 per cent say they have cut out dairy products all together," the coalition said.
"Many consumers are being misled into believing that extreme low-carb diets are healthy and that carbohydrates, not calories, are what contributes to weight gain and loss. According to the survey, 47 per cent of Americans now believe that low-carb diets create weight loss without cutting calories, a view that the overwhelming number of credible scientific studies refutes.
"Equally troubling, only 21 per cent of Americans know that low-carb diets are not recommended for people with diabetes, when in fact, the American Diabetes Association along with all the leading nutrition and public health groups, recommend that for optimal health as well as weight loss, people should consume a diet that includes a variety of foods primarily composed of carbohydrates, and especially fruits, vegetables, whole grains and low-fat dairy products."
As in the UK, the American survey revealed a very limited understanding of the amount of carbohydrates needed each day for good health, the coalition said. The US health authorities recommend that children and adults get a minimum of 130 grams of carbohydrate daily, but only 19 per cent of those surveyed knew this. Some 51 per cent of those questioned believed that adults need significantly less, while 21 percent had no idea - and only 10 per cent believed that adults needed more.
The UK groups concerned about low-carb diets have lent their support to an alternative diet regime, Vitality, but the US coalition will take more direct action, using a series of television and print ads and a new website to spread the word that "carbohydrates contain essential nutrients that provide fuel for the brain and muscles, contain the fibre needed for proper gut function, help to control body weight and have been demonstrated through numerous scientific studies to lower the risk for certain cancers, stroke, heart disease and high blood pressure".