The Portuguese validation of the Dietary Intent Scale

Abstract

Dietary restraint, the intentional restriction of caloric intake for the purpose of weight loss, is linked to maladaptive eating and lower mental and physical health. This study aimed to validate for the Portuguese population the Dietary Intent Scale (DIS), a measure of dietary restraint. The sample comprised 1077 participants (415 males), aged between 14 and 34 years old. Males presented a mean age of 18.09 (SD=3.32) and a mean BMI of 22.03 (SD=3.28), and females showed a mean age of 17.73 (SD=3.38) and a mean BMI of 21.32 (SD=2.86). No differences were found between genders regarding age. A reliability analysis revealed that DIS presented a Cronbach’s alpha of .92 and that three items did not contribute for the scale’s internal consistency. Therefore, and since their content was similar to other items, these three items were excluded. A confirmatory factor analysis revealed the adequacy of the final 6-item DIS, showing good local (SRWs between .64 and .94) and global adjustments (X2(8)=12.07, p=.148; CFI=1.00; TLI=1.00; RMSEA=.03, p=.876). Furthermore, the model showed invariance between genders. Finally, DIS revealed a good convergent validity (eating psychopathology, eating restraint, inflexible eating, body image-related experiential avoidance, body image-related cognitive fusion, depression, anxiety, and stress) and temporal validity (r = .82) DIS seems to be a short and valid measure of eating restraint, highly correlated with an important measure of eating psychopathology (EDE-Q). The DIS may represent an advantage in relation to other existing measures, particularly for research and community interventions regarding eating difficulties.