Objectives To model food group consumption and price of diet associated with achieving UK dietary recommendations while deviating as little as possible from the current UK diet, in order to support the redevelopment of the UK food-based dietary guidelines (now called the Eatwell Guide). Design Optimisation modelling, minimising an objective function of the difference between population mean modelled and current consumption of 125 food groups, and constraints of nutrient and food-based recommendations. Setting The UK. Population Adults aged 19â €..years and above from the National Diet and Nutrition Survey 2008-2011. Main outcome measures Proportion of diet consisting of major foods groups and price of the optimised diet. Results The optimised diet has an increase in consumption of potatoes, bread, rice, pasta and other starchy carbohydrates' (+69%) and fruit and vegetables' (+54%) and reductions in consumption of beans, pulses, fish, eggs, meat and other proteins' (-24%), dairy and alternatives' (-21%) and foods high in fat and sugar' (-53%). Results within food groups show considerable variety (eg, +90% for beans and pulses,-78% for red meat). The modelled diet would cost £5.99 (£5.93 to £6.05) per adult per day, very similar to the cost of the current diet: £6.02 (£5.96 to £6.08). The optimised diet would result in increased consumption of n-3 fatty acids and most micronutrients (including iron and folate), but decreased consumption of zinc and small decreases in consumption of calcium and riboflavin. Conclusions To achieve the UK dietary recommendations would require large changes in the average diet of UK adults, including in food groups where current average consumption is well within the recommended range (eg, processed meat) or where there are no current recommendations (eg, dairy). These large changes in the diet will not lead to significant changes in the price of the diet.