Aim of the study:
Among girls in adolescence dieting is a very common case. A decision about starting weight reduction is affected by various factors. In this age group, an unjustified tendency to lose weight is particularly intense. The aim of the study was the evaluation whether the application of weight loss diets by girls at high school age is justified.

Material and methods:
The study was conducted among 203 schoolgirls in three Warsaw high schools. The study used an anonymous survey, which looked at the phenomenon of the use of reduction diet and the perception of the body weight by the interviewed girls. On the basis of the calculated BMI the nutritional status of the respondents was evaluated.

Results:
It has been shown that almost half (47.8%) of the teens in question have used weight loss diets. Efforts of weight reductions have been undertaken by girls with normal (82.5%) and deficient body weight (7.2%); 61.1% of high school girls are unhappy with their weight, of which more than a half (53.2%) have the need for the reduction of it.

Conclusions:
Studies show that weight loss in adolescence is not justified, as the main factor which urges teens to reduce weight is incorrect perception of body fat and not the actual excess weight. Therefore, there is a need for teen education about health consequences of the use of diet without justification.