Popular slimming programmes do result in reduced energy intake while providing enough nutrients. A new scientific analysis, published today in BioMed Central's open access Nutrition Journal, provides comprehensive dietary data about Slim Fast, Atkins, Weight Watchers and Rosemary Conley's "Eat Yourself Slim" Diet & Fitness Plan.
Helen Truby worked with a team of academics from United Kingdom universities who studied the different diet plans. She described how the randomised controlled trial "provides reassuring and important evidence for the effectiveness and nutritional adequacy of the four commercial diets tested".
Truby and her colleagues asked 293 people from five regional areas around the UK to keep a diary of their food intake before and during the two-month diet period. There was also a control group who continued to eat as normal. They found that following any of the four diets did result in a drop in energy intake. The diets all resulted in a significant drop in body weight compared to the non-dieting controls, but there was no significant difference between the diets in the amount of weight lost.
Despite the fact that all of the diets apart from Atkins advise people to increase their fruit and vegetable intake, the authors found that the only dieters to do so were those on the Weight Watchers diet, and even they only had one more portion a day. According to Truby, "These disappointing findings suggest that people remain resistant to the advice to 'eat more fruit and vegetables', even when they are advised to as part of a modified weight loss programme".
Contrary to the popular controversy about the Atkins diet, the researchers found little evidence of short-term detrimental effects of nutrient intake as a result of this low-carbohydrate plan. However, they do mention that, "Atkins dieters tended to have a reduction in iron and niacin, probably due to a fall in the intake of cereal and flour, which is fortified in the UK. They also had a generally low intake of dietary fibre overall, which may have implications for bowel health in the longer term".
Based on their results, the authors suggest "commercial companies work in partnership with health professionals to identify high-risk clients and provide them with dietary advice that is tailored to their nutritional requirements".
- Helen Truby, Rebecca Hiscutt, Anne M Herriot, Manana Stanley, Anne deLooy, Kenneth R Fox, Susan Baic, Paula J Robson, Ian Macdonald, Moira A Taylor, Robert Ware, Catherine Logan and MBE Livingstone. Effect of commercial weight loss diets on macronutrient composition and micronutrient adequacy in free living adults participating in a randomised controlled weight loss trial. Nutrition Journal, (in press)
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