A prospective observational case-control study evaluating the effect of a weight loss intervention program on functional gastrointestinal disorders among overweight and obese children.

The investigators intend to conduct a prospective observational case-control study of overweight and obese children, aged 6-18 years, followed in the child health and sport center at Meir medical center, Kfar-Saba, Israel.

Overweight and obese subjects, defined as body mass index (BMI) percentile ≥85%, will be offered to participate. Healthy subjects with normal BMI percentile from other pediatric outpatient clinics as well as relatives and friends of physicians from the pediatric division will be enrolled and serve as the control group.

Study visits will be at enrollment and after 3 and 6 months of participation in the intervention program. During the visits the investigators will collect anthropometric measurements (height, weight, BMI, total body fat). Participants (age 10y and above) or their parents (age 6-10y) will fill a validated questionnaire for diagnosis of FGID based on ROME IV criteria. The investigators will also collect data from exercise capability testing and quality of life questionnaires performed regularly (and irrespective of this study) during the intervention program.

The investigators will then compare between subjects who succeeded to those who failed in losing at least 5% of their initial body weight as well as to healthy controls with normal BMI percentile.

Inclusion Criteria:

• obese / overweight children participating in the life style modification program at the child sport and health center

Exclusion Criteria:

• other known chronic non-functional gastrointestinal conditions (e.g. Celiac disease, inflammatory bowel disease)

obese and overweight subjects patricipating in the life style modification program as well as healhy controls of normal weight