This is a 12 month prospective observational cohort study of the outpatient protein-sparing modified fast diet for children with severe obesity and serious comorbid condition(s). The study will enroll 30 Center for Healthy Weight and Nutrition patients aged 11-19 years who have been placed on a protein sparing modified fast as part of their treatment plan. The study-specific procedures consist of questionnaires/interviews on diet and PA behaviors, adherence and self-efficacy measures, data abstraction from the chart and tracking of activity using a Fitbit.

Aggressive dietary interventions may provide an accessible treatment option for children and adolescents with severe obesity who are not successful with traditional lifestyle behavioral interventions or do not want or qualify for weight loss surgery. One such intensive dietary option is the protein sparing modified fast (PSMF). The PSMF involves minimal carbohydrate intake to induce ketosis, while maintaining adequate or high protein intake to minimize catabolism. The PSMF, under medical supervision, can be an effective and safe intervention for children and adolescents, yet the PSMF diet is not regularly used in the treatment of pediatric severe obesity. This pilot study will employ a prospective cohort study design. Thirty children, 11-19 years-old, with severe obesity, who have been prescribed the rPSMF as part of their treatment in a tertiary care pediatric weight management clinic (PWMC), will be recruited along with their attending parent to participate in the study. The primary aim of the study is to evaluate the acceptability of the rPSMF as assessed by adherence, satisfaction with the intervention, and participation rate using quantitative and qualitative methods. The secondary aim is to investigate the effectiveness of the rPSMF on improving a) anthropometric measures (weight, body mass index [BMI] and BMI z-score); b) metabolic measures (lipid profile, glycosylated hemoglobin, liver function tests); and c) quality of life. Results of this study will provide guidance for the standardization of a pediatric rPSMF protocol in a clinic setting, delineate which factors improve or hinder adherence and weight loss and provide preliminary data for a multicenter randomized controlled trial.

Inclusion Criteria:

• Children Age 11-19 years old
• Must be severely obese (BMI greater than or equal to 120% of the 95th percentile for their age and sex, or a BMI of 35 or greater)
• Must have at least one severe comorbidity
• Tanner Stage III, IV, V

Exclusion Criteria:

• non-English speaking
• Patients without adequate social/psychological capacity, as evidenced by unavailability to recourses, or family is unable to provide support.

Children and adolescents seen by Center for Healthy Weight and Nutrition at Nationwide Children's Hospital