While adolescents with obesity and extreme obesity are at increased risk for health complications, especially adolescents with extreme obesity rarely seek medical care, and sustained weigh loss is hardly ever achieved. One of the underlying reasons might be the lack of adequate treatment options.

In this multicenter study, we aim to test a new, low key group intervention focusing on improving compliance and psychosocial functioning. The study is a subproject of the Medical and psychosocial implications of adolescent extreme obesity - acceptance and effects of structured care, short: "Youth with Extreme obesity Study (YES)", which aims at improving the medical care and social support structures for youth with obesity and extreme obesity in Germany.

Obese youth and young adults (BMI ≥ 30kg/m2) between the ages of 14 and 24.9 years (initially up to 21 years) are eligible to participate. Participants will be asked to complete a series of questionnaires on their general health, psychosocial situation and wellbeing, and will be offered a thorough medical evaluation. Individuals who complete the baseline evaluations will be invited to participate in 6 group sessions over a 3 months period. Group assignment to the psycho-social intervention vs. routine care group will be at random, like throwing a dice. After 6 months, participants will complete further questionnaires to evaluate the effects of the interventions on quality of life and psycho-social functionning.

The study will show the acceptance and effectiveness of a new intervention focusing on improving compliance and psychosocial functioning in adolescents with extreme obesity, and thereby inform the development of new treatment and support options for these adolescents. If interested, participants are invited to participate in additional components of YES, and to receive medical care and psycho-social support.

While obese youth are at high risk for co-morbidities, especially the extremely obese individuals rarely seek medical care. The underlying reasons are poorly understood, but patient inherent factors and the lack of adequate treatment options may play a role.

In this multicenter study, we aim to assess the acceptance and effectiveness of a manual based low key group intervention focusing on improving compliance and psychosocial functioning in adolescents with morbid obesity (BMI≥35kg/m2), in comparison to routine care. Youth with more moderate degrees of obesity (BMI 30-34.9kg/m2) will serve as an additional control group. The study is part of the Medical and psychosocial implications of adolescent extreme obesity - acceptance and effects of structured care", short: "Youth with extreme obesity Study (YES), which also comprises the recruitment and characterization of obese (BMI 30-34.9kg/m2) and extremely obese (BMI ≥ 35kg/m2) youth from different healthcare- and non healthcare settings, a structured prospective evaluation of adolescent bariatric surgery, economic assessments of the financial burden of extreme adolescent obesity on the healthcare system, and a long-term prospective observation study.

Based on the current state of knowledge, we will test the a priori ordered hirarchy of hypotheses:

1. The compliance rate 6 months after randomization is higher in subjects in the low key intervention group compared to the standard care group.
2. Covariant-adjusted changes in quality of life (assessed by DISABKIDS scale) between baseline and the 6 months follow up will be more pronounced in the low key intervention group compared to the standard care group.

The five participating university centers are distributed across 4 geographic regions in the North (Berlin), in the West (Essen/Datteln), in the East (Leipzig) and in the South (Ulm) of Germany, and will therefore render data that are representative of Germany as a whole. We will screen a 600 adolescents age 14 to 24.9 years (initially up to 21 years; this was changed in an amendment in February 2013) with extreme obesity (BMI ≥ 35 kg/m2) and 600 adolescents with obesity (BMI 30-34.9 kg/m2) over a 24 months period. A total of 350 subjects will be enrolled. Baseline assessments include an array of standardized questionnaires and validated instruments to assess health, psycho-social situation, psychiatric co-morbidities and health related quality of life, as well as an in-depth medical evaluation. Individuals who complete the baseline evaluations will be invited to participate in 6 group sessions over a 3 months period. Group assignment to the low key intervention vs. standard care group will be at random. The effects of the interventions on health related quality of life and psycho-social functioning will be assessed via questionnaires after 6 months. Subsequently, subjects will be invited to participate in additional components of YES.

The project will reveal the effectiveness and safety of a manual based low key group intervention focusing on improving compliance and psychosocial functioning in adolescents with morbid obesity, and thereby inform the development of new treatment and support options for these adolescents in Germany.

Inclusion Criteria:

• BMI ≥30kg/m2
• sufficient German language skills

Exclusion Criteria:

• Circumstances that require immediate inpatient care (e.g. severe somatic or psychiatric illness)
• obvious cognitive disability