Since 2013, obesity services in the UK National Health Service (NHS) have focused on a tiered structure, with tiers 3 (specialist weight management services) and 4 (primarily bariatric surgery) commissioned by Clinical Commissioning Groups (CCGs) and widely reported as cost effective and recommended by national guidelines. However, CCGs have been reluctant to fully conform to the guidance. We explore how the different evaluative perspective of those generating evidence from local decision makers has contributed to this failure of the CCGs to provide services considered cost effective. We explore four elements where the conventional economic evaluation framework, as applied by the National Institute for Health and Care Excellence (NICE), differ from the reality faced by local decision makers: the cost-effectiveness threshold, the implications of decision uncertainty and budgetary excess, the valuation of future costs and outcomes, and the scope of included costs. We argue that the failure of the conventional framework to reflect the reality faced by local decision makers is rendering much of the existing literature and guidance inappropriate to the key commissioners. Our analysis demonstrates that it is not reasonable to assume that the framework of economic evaluation used to inform national guidance applies to local decision makers, such as in the commissioning of weight loss services. This failure is likely to apply to the majority of cases where evidence is generated to inform national decision makers but commissioning is at a local level.