A new study published in the New England Journal of Medicine had intended to determine which of three weight loss diet works best: low-carbohydrate, Mediterranean, and low-fat. Instead, the study revealed that most diets don't work and that weight loss is just plain difficult. In fact, obese people in the study only lost an average of 2.7 to 4.5 kilos over a period of two years.
The study followed 277 men and 45 women dieters. They were each assigned to one of three groups: a 30 percent fat diet based on American Heart Association recommendations, a low-carbohydrate diet based on Atkins, and a Mediterranean diet. The study was conducted in Israel in an isolated workplace location where food intake could be carefully monitored.
Participants met regularly with dieticians, and spouses were provided with nutrition counselling, and food offerings in the workplace were designed to support the intervention. Every effort was made to help dieters comply with their assigned plan.
The first five months were the most successful, and saw the most weight loss. The participants on the low-fat and Mediterranean diets lost about 2.7 kilos and the low-carb folks lost about 6.3 kilos.
After two years, everyone had regained some of the weight. The Mediterranean and low-carb dieters maintained about a 4.5 kilo loss, and the low fat dieters kept 2.7 kilos off after two years. Despite the relatively small losses, everyone enjoyed improvements in cholesterol levels and other health indicators.
Iris Shai, the study's lead author and a registered dietitian at Ben-Gurion University of the Negev at the S. Daniel Abraham International Center for Health and Nutrition said, "In order to keep participants on the weight loss diet for long term as a way of life, we did not impose extreme diet protocols. More dramatic diet protocols could probably reduce more weight for the short term, but participants would have dropped out."
Interestingly, men were more successful on the low-carb diet than on the Mediterranean diet, and women lost more weight on the Mediterranean diet than on the low-carb plan.