Short term benefits of weight loss seem outweighed by longer term cardiovascular harms Low carbohydrate-high protein diets and their combinations (such as the Atkins diet) have become popular worldwide and are frequently adopted for weight control by lay people. These diets have also been suggested to have health benefits over low fat diets, mainly on the basis of results from short term intervention studies. These benefits include reductions in plasma triglyceride, glycated haemoglobin, and insulin concentrations as well as in systolic blood pressure,1 2 3 with consequent improvements in conditions such as type 2 diabetes and non-alcoholic steatohepatitis.4 However, the long term health effects of low carbohydrate-high protein diets are unclear, particularly as adherence to them has been associated with higher mortality from cardiovascular diseases in prospective cohort studies.5 6 7 These conflicting results have fostered a debate over the benefits and risks of such diets.4 In the linked article (doi:10.1136/bmj.e4026), Lagiou and colleagues investigated the association between adherence to low carbohydrate-high protein diets and the incidence of cardiovascular disease in a prospective cohort of 43 396 Swedish women followed for …