To the Editor: Low-carbohydrate diets have re-emerged into the public spotlight and are enjoying widespread popularity. However, current evidence indicates that low-carbohydrate diets have no significant advantage over more traditional energy-restricted diets for long-term weight loss and maintenance.1-3 While these diets have shown short-term efficacy in modifying some lipid parameters and measures of insulin sensitivity, questions remain about the risk of adverse effects with long-term carbohydrate restriction.4

The scientific literature has not addressed the questions of how the general public perceive these diets, and what dieting approaches they adopt. Dieting perceptions and practices within the community may be far removed from the strictly controlled situation of published research.

A national telephone survey of 1200 adults aged 18 years and over was conducted by the private market research company Newspoll from 6 to 8 August 2004. The survey asked about knowledge of and attitudes to carbohydrates and dieting. Telephone numbers were randomly selected, with a quota for capital city and non-capital city areas. Selection of an individual in each household was based on the last birthday. Response rate to the survey was 11%. Sex, age, marital status and working status demographics were representative of the Australian adult population.

The main findings are summarised in the Box. Most of those surveyed correctly identified foods such as pasta and bread as “carbohydrate foods”. Only a third of people identified soft drinks and lollies as carbohydrate foods, and 20% incorrectly identified cheese and eggs as carbohydrate foods. Almost 17% of people had either tried, or intended to try, a low-carbohydrate diet, with women more likely to have tried this diet. Half of those surveyed believed that carbohydrate foods should make up a quarter or less of the daily diet (current health recommendations are that about half the diet should comprise carbohydrates). Almost 70% of those surveyed believed they needed to cut back on carbohydrates to lose weight.

Based on this survey, low-carbohydrate dieting practices are as widespread in Australia as in the United States.5 Interestingly, the US study noted a greater propensity to use carbohydrate-reduced diets among those who were obese, had diabetes, hypertension or high cholesterol.

Our data demonstrated widespread misunderstanding of what constitutes a high-carbohydrate food, which may leave many individuals at risk of choosing a diet that selectively excludes wholegrain foods, fruits and some dairy products. Health professionals should be aware that low-carbohydrate diets remain popular, that the people who are following these diets may represent a more “at risk” population, and that the food choices made by those following this dietary pattern may have adverse long-term health effects.