The proposed study is a randomized, open, comparative research involving an intervention group and two control groups.

The aims of the study are: 1.To compare levels of depression in female adolescents with obesity and a control group of female adolescents with appropriate weight and height. 2. To investigate whether a decrease in weight due to a short range intervention program provided by dietician for female adolescents with obesity will lead to change in the levels of symptoms of depression and cognitive and executive functions in comparison to a control group of adolescent girls with obesity, matched in age that does not receive such an intervention program.

60 Female adolescents with obesity will be recruited to the study and will be randomized to 1 of two groups- 1. intervention group- participants in this group will attend an intervention program consisting of 12 meetings with dietician and will attend two study visits at the clinic- in the beginning of the study and after three months. 2.Control group- Participants in this group will only come to two study visits at the clinic. In the first two visits they will meet with a dietician and will receive nutrition guidance.

Another 30 girls with appropriate weight will be recruited to second control group- this group will come to two study visits at the clinic- in the beginning of the study and after three months. In the first visit participants will receive nutrition guidance by the dietician.

In the study visits the following procedures will be performed for all study groups: Blood tests, completion of psychological and nutritional questionnaires, completion of computerized tests and measurements of height, weight, fat mass and circumference of hips.

Inclusion Criteria:

1. Adolescent girls aged 12-17, who attend the Endocrinology Institute in Schneider Hospital and comply with the research criteria: obesity (BMI above percentile 85) and appropriate weight (BMI between percentiles 5-85).
2. Adolescent level according to Tanner: 4-5.
3. Participants with obesity: BMI above percentile 85 for age group.
4. Participants in control group with appropriate weight: BMI percentile 5-85 for age group.
5. Appropriate height (Percentiles 3-97 according to the CDC curve).
6. Parents' signature on informed consent form.

Exclusion Criteria:

1. Chronic illness or chronic use of medications.
2. Inability to comply with the research conditions.