Los avances en historia ambiental en la Argentina

There are several limitations related to this study; some associated with the study itself and some with the previous research used as a basis of comparison, and each will be explained in this section of the thesis.

One of this study’s limitations was the nature of the sample similarities. The study sample is relatively heterogeneous with regards to age, but regarding other sociodemographic factors, like sex, income and education, the study sample were very homogeneous. Furthermore, they were all current or former weight reduction program participants, which emphasize the fact that the results of this study most likely are not appropriate for generalization. Additionally, the very low response rate increases the chances of the results displaying a distorted picture of the actual target population, and as such decrease the strength of the results.

An important aspect to underline with regards to the cited studies is that they vary greatly in their study design, which might decrease the strength of comparability. For example, some studies estimate predictions based on only pre-treatment measurements (Teixeira et al., 2004a; Teixeira et al., 2004b; Teixeira et al., 2005), comparison of pre- and post-treatment measurements (Palmeira et al., 2007; Steptoe, Perkins-Porras, Rink, Hilton, & Cappuccio, 2004; Teixeira et al., 2010), baseline, post treatment and follow up measurements (Pasman et al., 1999; Shannon, Bagby, Wang, & Trenkner, 1990) or cross-sectional measurements (Sporny & Contento, 1995; Watters & Satia, 2009). Most likely, the longitudinal studies, with measurements taken at several points in time during the behavior change phase (e.g. initiation-, action- and maintenance phases) provide more solid evidence regarding predictors and associations, as the same measures have been taken at several points in time and can therefore also give an estimation of changes in these factors, as well as the establish the direction of causality of the variables, in addition to revealing pretreatment and post treatment predicting factors.

With regards to the previous research which the results have been compared to, there were very few studies which were identical to this study in relation to the end measure; a composite measure of maintenance of a healthy diet. Therefore, it was decided to include studies aimed at investigating similar factors as that in this study, but associated with a) specific components of a healthy diet (like fruit and vegetable consumption and lower fat intake) or b) weight loss maintenance. The reasons for this are explained in the following three subchapters.

124

5.2.2.1 Dietary behavior studies

It is important to note that none of the studies explored in relation to psychosocial factors and dietary behavior, specified that they had been conducted with people enrolled in a weight reduction program, but rather chiefly in the general adult population. Hence, there might be different predictors related to maintenance of a healthy diet after initiation of a weight reduction program than for that of adults not having participated in such programs. However, as the dependent variable, maintenance degree of a healthy diet, is a composite measure of maintenance of a healthy diet, including measures like eating the recommended fruit and vegetable serving, and limiting intake of fatty foods, it was believed that the results could be comparable to these previous studies, even though they were not conducted within the same context as this study. Still, these studies have only looked at individual dietary behaviors associated with having a healthy diet, e.g. consumption of fruit, vegetables, fruit and fat, rather than maintaining an overall healthy diet as in this study. Nevertheless, as items measuring similar dietary behaviors as that of those studies were included in this study’s dependent variable, it was believed that they were adequately comparable.

5.2.2.2 Weight loss maintenance studies

Considering comparison with weight loss maintenance studies as relevant for this study was due to the fact that most studies which have aimed at investigating similar factors to that of this study in relation to weight reduction program attendance, have been done so with maintenance of weight loss as the end measure (Byrne et al., 2004; Carraca et al., 2011; Edell, Edington, Herd, O'Brien, & Witkin, 1987; McGuire et al., 1999; Palmeira et al., 2007; Teixeira et al., 2004a; Teixeira et al., 2004b; Teixeira et al., 2005; Williams et al., 1996), rather that maintenance of a healthy diet. Hence, their dependent variable is the result of a series of enacted behaviors, rather than a specific behavior in itself which is the case for this study. However, it was believed that they could be compared to the results of this study, assuming that their assessment of the factors similar to those in this study involved some investigation of eating behavior in relation to those factors and that the weight loss mirrored some degree of dietary behavior modification.

125

5.2.2.3 Weight loss maintenance vs. maintenance of a healthy diet

An additional consideration which is important to make is the time definition discrepancy between maintenance of a healthy diet and weight loss maintenance. For the purpose of this study, the maintenance phase of continuing with a healthy diet was defined as initiated after commencement of the weight reduction program, hence participants who were still participating in the program were considered to be in the healthy diet maintenance phase, whereby this would not be the case in the studies investigating weight loss maintenance. The time aspect definition of the weight loss maintenance phase is somewhat illusive, as some researchers indicate that it begins at around the six month mark after initiating weight loss efforts (James et al., 2000; Ulen et al., 2008), while others define it as commencing twelve months after weight loss initiation (Douketis, Macie, Thabane, & Williamson, 2005). However, independent of this somewhat vague definition, it is clear that weight loss maintenance is not begun immediately after weight loss initiation.