The desire to control food intake in order to avoid weight gain or to lose weight is widespread among university students (1). However, evidence regarding the association between cognitive restraint and dietary intake is conflicting (2). The main objective of our study was to determine whether students with high restraint behavior differ from low-restraint students in relation to dietary intake. The study was divided into two phases.
In the first phase, after obtaining permission from the authors, we translated and adapted the "Three-Factor Eating Questionnaire" (TFEQ) (3), and studied the construct validity of the scale with a sample of 194 students from the University of Porto (UP) - 97 female, 97 male. In the second phase, a sample of 380 students (60% female, 40% male) from UP, scoring high and low on measures of dietary restraint and disinhibition, as measured by the TFEQ, was studied. Dietary intake was obtained using a semi-quantitative food-frequency questionnaire (FFQ) developed and validated for Portuguese adults(4). Smoking habits, anthropometric and physical activity data were also collected. The association of restraint and disinhibition with nutritional and dietary variables was tested using multivariate analysis of variance (MANOVA) in a 2x2 factorial design (high/low restraint x high/low disinhibition). Depending variables were energy and nutrients, or food intake. Effects were further analysed using univariate analysis of variance (ANOVA).
Factorial loadings and eigenvalues for each factor (restraint, disinhibition and hunger) from the Portuguese version of the TFEQ seemed to be adequate, and reliability for subscales was elevated. The MANOVA for nutritional and dietary data found significant main effects for restraint. Effects due to dietary restraint exhibited a different pattern in each sex, namely for energy consumption. When comparing high and low restraint groups, among women, high restrainers reported lower consumption of energy (2062 Kcal versus 2208 Kcal, p < 0,01), pastry (45 g versus 64 g, p < 0,05), bread/cereals/pulses (303 g versus 323 g, p < 0,05) and higher consumption of vegetables (149 g versus 112 g, p < 0,01), and sea food (85 g versus 64 g, p < 0,001), than low restrainers, even after adjustment for potential confounders (energy, body mass index and physical activity). In male subjects, we didn't find statistically significant differences in energy consumption between restraint groups, but high restrainers consumed significantly more vegetables than low restrainers (128 g versus 55 g, p < 0,05).
The results emphasize the association between high restraint behavior and lower reported energy consumption in women, but not in men, and a general better food pattern in males and females from the high restraint groups.
(1) Moreira P., Sampaio D., de Almeida MDV. Weight control strategies in a sample of Portuguese university students. Appetite 2002; 39(3):250.
(2) French SA, Jeffery RW. Consequences of dieting to lose weight: effects on physical and mental health. Health Psychology 1994;13:195-212.
(3) Stunkard AJ, Messick S. The Three-Factor Eating Questionnaire to measure restraint, disinhibition and hunger. Journal of Psychosomatic Research 1985;29:71-83.
(4) Lopes C., von Hafe P., Ramos EE., Fernando PB., Maciel MJ., Barros H. Alimentacao e risco de enfarte do miocardio: Estudo caso-controlo de base comunitaria. Acta Medica Portuguesa 1998;11:311-7.
P. Moreira, M.D.V. de Almeida - University of Porto, Portugal
D. Sampaio - University of Lisboa, Portugal