The objective of this study was to adapt the design of our weight management intervention to the needs, expectations and capabilities of potential users. In study 1, we interviewed 25 people about their experiences of weight management. The findings of these interviews were combined with findings from existing theory and research in a process of ‘intervention planning’ that informed the design of the intervention. Study 2 comprised in-depth think-aloud studies with a further 16 people interested in using a web-based intervention to manage their weight, in order to elicit reactions to the intervention techniques and materials. In study 1, overly intrusive and restrictive aspects of eating self-regulation were commonly cited reasons for failure to maintain weight management long-term. We therefore designed an intervention with a more flexible approach to autonomous self-regulation. This approach was broadly welcomed in study 2, but there were indications that some participants might have difficulty effectively implementing self-regulation techniques independently. A flexible and autonomous approach to changing eating habits is attractive to potential intervention users but may be difficult for some users to implement successfully.