The main objective of the Dietary Intervention Randomized Controlled Trial (DIRECT) was to compare the efficacy and safety of 3 weight-loss strategies. In this 2-year trial, 322 moderately obese subjects were randomized to either 1) low-fat diet, restricted calorie 2) Mediterranean diet, restricted calorie, or 3) low carbohydrate diet, non-restricted calorie. The rate of adherence to this study diet was quite elevated (95.4% at 1 year and 84.6% at 2 years). Investigators of the DIRECT study reported a mean weight loss of 2.9 kg for the low-fat group, 4.4 kg for the Mediterranean-diet group, and 4.7 kg for the low-carbohydrate group. An important aspect of this study is the fact that several emerging markers of cardiometabolic risk were measured. The three interventions had different impacts on the plasma levels of these cardiometabolic risk markers. A subanalysis performed among participants who had diabetes at baseline (n=36) showed that those assigned to the Mediterranean diet had greater improvements in glucose and insulin levels than those assigned to the low-fat diet. Based on the fact that the low-carbohydrate diet had a more beneficial impact on the lipid profile than the Mediterranean diet, which had a more positive effect on markers of plasma glucose-insulin homeostasis, DIRECT study investigators suggested that personal preferences along with the metabolic status of individuals should be taken into consideration before assigning patients to specific weight-loss diets.
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