In recognition of the fact that poor diet quality is a leading cause of malnutrition and non-communicable disease, the government of Ghana considers improved food security and nutrition outcomes as priority development objectives. Using three rounds of household expenditure surveys, this study assesses the trends in diet quality as measured by the Reference Diet Deprivation (ReDD) index, a composite measure of the incidence, breadth, and depth of diet deprivation. Assessed against Ghana’s newly launched food-based dietary guidelines, we find that diet quality improved noticeably between 2005/06 and 2012/13, although two-thirds of those gains were eliminated as diets deteriorated again between 2012/13 and 2016/17. Our results call for policies that raise real incomes, reduce the relative prices of nutritious foods, promote agricultural diversification, and create awareness of healthy eating. Further analysis and better food price data are required to refine diet costing methods. This would provide valuable additional insights into the issue of cost and affordability of healthy and nutritious diets in Ghana.