Promotion of healthier eating choices and adherence to recommended dietary norms are important elements of the UK Government’s food strategy to combat the rising incidence of obesity. This paper explores the paradox of rising incidence of obesity over the last two decades even as consumers have moved towards healthier dietary choices. We analyse data from the UK’s National Diet and Nutrition Surveys over this period using quantile regression and counterfactual decompositions to identify the main elements underlying this paradox. We find that adherence to individual dietary norms in isolation has only very modest impacts on the obesity profile of the population. Efforts to promote compliance with some of the norms may have the unintended consequence of increasing excessive calorie consumption, leading to increased obesity. The effects of improved adherence to dietary norms may be offset by the changes in the impact of adherence to norms on excessive energy intake. Our results suggest that nutrition and policy and interventions need to focus on the simultaneous compliance with a range of dietary norms to have a significant impact on the incidence of obesity.