Obesity is the sixth most important risk factor contributing to the worldwide burden of disease . It is associated with cardiovascular disease (CVD), diabetes, cancer, osteoarthritis and chronic pain [1–3] as well as with negative psychosocial and/or psychological effects [4–7]. These negative psychological impacts have been observed in response to negative portrayal in the media,  inequities in the employment setting [4, 7] and inequities in health care .
Many studies have focused on the consequences of being overweight or obese [1–3, 8] rather than the relative importance of, and the complex interaction between, factors contributing to these conditions [9, 10]. An individual’s weight is the result of a combination of biological, behavioral and environmental factors . Given the current state of scientific research, these behavioral and environmental factors are modifiable by the individual or society, while the biological factors, such as genetic predispositions, are less subject to modification. However, it is important to acknowledge that the effect of a genetic susceptibility to being overweight or obese is also modifiable by behavioral factors such as a physically active lifestyle .
Some short-term obesity treatment programs have shown significant weight loss among adults [13, 14]. However, this is typically followed by weight gain resulting in rather modest long-term results [15–17]. Further research is therefore needed to understand how successful long-term weight maintenance can be achieved . A shift from focusing exclusively on weight loss, to also including a focus on weight maintenance has been suggested [19–21]. Regardless of the focus, there is no clear consensus on how to intervene to promote either weight loss or weight maintenance .
Weight maintenance has been defined as a person's ability to maintain their weight within ± 3% of a baseline value over a defined time period . Previous studies on weight maintenance have most often focused on secondary weight maintenance (SWM), i.e. maintaining a reduced weight following weight loss. Two central factors known to be important for SWM are regular physical activity and healthy eating habits [23–27]. Other factors that have been identified include having an accurate self-image , a high self-esteem , a positive body image , consciousness of one’s own behaviour , positive self-talk  taking responsibility for one’s actions , and the ability to cope with stress and confront problems directly [23, 27]. Further, successful secondary weight maintainers monitored weight fluctuations and had a clear alarm signal for weight gain that triggered immediate action . They also had clear strategies for coping with lifestyle interruptions. When compared with re-gainers, maintainers more often continued to use the strategies they had acquired during weight loss . In addition, a study on mediators of weight loss and weight loss maintenance showed that lowering emotional eating and adopting a flexible dietary restraint pattern were critical for sustaining weight loss .
In several studies on SWM, the subjects did not fare well at maintaining their weight after weight loss [13–17]. It is possible that this limited success is partially a consequence of the antecedent weight gain. It can therefore be theorized that a subject who has not experienced this initial weight gain may be more successful in weight maintenance. We propose that with two subjects with a Body Mass Index (BMI) of 24, the subject who has reduced his/her weight to reach that BMI will have more difficulty remaining there than the subject who never has exceeded a BMI of 24. Further, enabling subjects to prevent initial weight gain spares them the difficulty of trying to get down to a lower weight. Prevention of initial weight gain would also reduce the large burden placed on the entire population to lose weight.
The concept of preventing weight gain among normal weight or overweight individuals is called primary weight maintenance (PWM).
Qualitative interviews conducted previously by the authors identified four main strategies related to PWM: “to rely on heritage”, “to find the joy”, “to find the routine” and “to be in control” . Nested within these four main strategies were eleven “ideal types”. These ideal types were theoretical constructs that captured the attitudes, strategies and behaviors related to weight maintenance. Knowledge of how these factors are distributed within the population would contribute to a deeper understanding of PWM and lay the ground work for the development of intervention programs.
Since PWM has received relatively little attention in the literature, there are currently no obesity prevention programs that are employing it. While the assumption may exist that an intervention focused on PWM would proceed in an identical manner to one directed at weight loss and/or SWM, this has not been scientifically established. Given the limited long-term success of weight loss programs in general, a new approach, starting with the development of an understanding of the factors related to PWM, is warranted.
To identify attitudes, strategies, and behaviors that are predictive of PWM in different age, sex and BMI groups in Northern Sweden.
To quantitatively validate the existence of the eleven ideal types that were previously identified in a qualitative study.