Context

Dietary interventions are the mainstay of behavioural obesity management, but exactly what type of diet may be most beneficial remains a matter of controversy.1 Thus, both academic and popular literature is flush with arguments in favour of specifically altering the macronutrient composition of diets for weight loss, be it to restrict calories from carbohydrates or fat intake or to increase protein intake. Commercial interest in these approaches ranging from multimillion corporations (eg, Weight Watchers, Atkins) to bestselling authors (eg, the Zone Diet); all promise easy and sustained weight loss. However is there really a big difference between the efficacy and effectiveness of these diets? This is the central question of the two studies.