The quality of life of adolescents who think they are too fat is worse than for adolescents who really are obese. This was a result of the all Germany Health Interview and Examination Survey for Children and Adolescents (KiGGS) of the Robert Koch Institute, as presented by Bärbel-Maria Kurth and Ute Ellert in the current edition of Deutsches Ärzteblatt International (Dtsch Arztebl Int 2008, 105: 406-12).
In the course of the KiGGS study, almost 7000 boys and girls aged between 11 and 17 years were weighed and asked about their self-assessment, ranging from "far too thin" to "far too fat." In addition, they all completed a questionnaire about quality of life. As a result of their analysis, the scientists established that about three quarters of adolescents are of normal weight. Almost 55% of the girls, but just under 36% of the boys thought that they were "too fat," although only about 18% of the adolescents were actually overweight. 7% to 8% of the adolescents were underweight.
The quality of life is lower in obese adolescents. However, this correlates to a large extent with self-evaluation. If adolescents think they are "far too fat," they forfeit a lot of their quality of life, whatever their actual weight. This is particularly marked with girls. On the other hand, if they consider their weight "just right," their quality of life is the same as if they were of normal weight, even if this is not true. The proportion of adolescents who think they are overweight has been increasing more rapidly in recent years than the proportion of those who really are overweight.
In an accompanying editorial, Johannes Hebebrand points out that adolescents are exposed to considerable social pressure to be thin. He thinks that it is remarkable that as many as 40% of the subjects thought that their weight was right, in spite of the ideal of slimness and the stigma of being overweight.