BACKGROUND: Dietary weight loss interventions most often result in weight loss, but weight maintenance on a long-term basis is the main problem in obesity treatment. There is a need for an increased understanding of the behaviour patterns involved in adopting a new dietary behavior and to maintain the behaviour over time.

PURPOSE: The purpose of this paper is to explore overweight and obese middle-aged women's experiences of the dietary change processes when participating in a 2-year-long diet intervention.

METHODS: Qualitative semi-structured interviews with 12 overweight and obese women (54-71 years) were made after their participation in a diet intervention programme. The programme was designed as a RCT study comparing a diet according to the Nordic nutrition recommendations (NNR diet) and a Palaeolithic diet (PD). Interviews were analysed according to Grounded Theory principles.

RESULTS: A core category "Engagement phases in the process of a diet intervention" concluded the analysis. Four categories included the informants' experiences during different stages of the process of dietary change: "Honeymoon phase", "Everyday life phase", "It's up to you phase" and "Crossroads phase". The early part of the intervention period was called "Honeymoon phase" and was characterised by positive experiences, including perceived weight loss and extensive support. The next phases, the "Everyday life phase" and "It's up to you phase", contained the largest obstacles to change. The home environment appeared as a crucial factor, which could be decisive for maintenance of the new dietary habits or relapse into old habits in the last phase called "Crossroads phase".

CONCLUSION: We identified various phases of engagement in the process of a long-term dietary intervention among middle-aged women. A clear personal goal and support from family and friends seem to be of major importance for long-term maintenance of new dietary habits. Gender relations within the household must be considered as a possible obstacle for women engaging in diet intervention.