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Obesity in Youth History

Specialty Care

The specialty care research team was built on an existing inter-disciplinary clinical team, Dr. Jill Hamilton, Dr. Catherine Birken, Dr. Beth Dettmer, and Dr. Jacob Langer, which assesses and treats patients with severe overweight. The efforts of these physicians have culminated in the opening of a complex obesity clinic at The Hospital for Sick Children (SickKids) charged with the management of complicated cases of childhood obesity.  

Overweight and obese children are recruited from the aforementioned tertiary-care level clinic at SickKids, a secondary-care level obesity clinic located at North York General Hospital, Dr. Glenn Berall, as well as from community-based primary care practices. From this focus, the team will incorporate basic researchers.

Dr. Harvey Anderson and Dr. Paul Pencharz hold a Canadian Institute of Health Research (CIHR) operating grant which focuses on appetite regulation and dysregulation in obese children. Dr. Michael Riddell has experience measuring exercise capacity and energy homeostasis in healthy children and in children with diabetes, as well as with hormonal regulation of exercise and stress.

Synergy will be created between the clinical team and researchers to implement and expand the proposed research program, as well as to provide cross-talk with the primary care research team. Further collaboration within the specialty care arm of the HISTORY team includes researchers from a large distribution of medical disciplines.

  • Khosrow Adeli, PhD, is Head of Clinical Biochemistry, SickKids, and has a research focus in lipid disorders and childhood obesity, particularly regarding fructose metabolism. He is a principal investigator for a study aimed at developing normal values for biochemical tests in children.
  • Denise Ernst, PhD, is Clinical Psychologist and a motivational interviewing certified instructor, who will provide expertise regarding behavioral counselling.
  • Simon Ling, MD, is a SickKids paediatric gastroenterologist with a research interest in non-alcoholic steatohepatitis in obese children.
  • Indra Narang, MD, is a SickKids paediatric respirologist with a research and clinical interest in sleep apnea and sleep disorders in obese children.
  • Rose Geist, MD, is a SickKids child psychiatrist with an interest in disordered eating and obesity. She will provide expertise to the team regarding psychiatric (depression, eating disorders) and behavioral issues.
  • Farid Mahmud, MD, is a SickKids paediatric endocrinologist with expertise in cardiometabolic risk. He will provide resources and expertise regarding non-invasive markers of early atherosclerosis.

With the growing population of overweight and obese children, there is a greater need for understanding the physiologic and behavioral determinants, the pathophysiology of metabolic abnormalities, and the development of appropriate interventions. Children who have developed morbidities secondary to obesity often require specialized care for more global metabolic assessment and more intensive and directed intervention. 

There are very few coordinated clinical or research programs expressly devoted to children, although specific sub-specialists may be managing patients for specific morbidities, and basic researchers may be investigating specific determinants or physiologic aspects. We propose a tertiary care setting-based integrated and synergistic research program that will bring together clinical and basic researchers in order to evaluate a) key determinants of metabolic risk, b) the role of sedentary behaviour and physical activity in determining metabolic risk, c) the interaction of the behavioural response of food intake and caloric compensation to alterations in satiety hormone responses, and d) feasibility of motivational interviewing to alter behavior in overweight, obese and morbidly obese children and adolescents recruited from secondary and tertiary care obesity clinical settings.   

The work of the specialty care arm is to answer the following research questions:

What factors influence appetite regulation and energy metabolism in children?

What factors determine metabolic risk associated with adiposity in children?

Process and Data Collection

Children and teens, aged 8-18 years, are being recruited at the SickKids complex obesity clinic, with referrals from the SickKids general paediatric clinic, lipid clinic, and sleep clinic. In addition, these recruits will also arrive from Dr. Berrel’s clinic at North York General and through community primary care clinics.

The recruits will follow one of two possible research paths.  Fifty recruits, BMI>85th percentile, will undergo cross sectional observation which involves two visits to SickKids.  Twenty four recruits, who have had a clinical decision to undergo bariatric surgery and are greater than 200 per cent of their ideal body weight, will undertake longitudinal observation.  This includes two visits at baseline, and further two visits at pre-op, six month post-op, and 12 month post-op.  These visits include are designed to collect data on the following measures:   

Visit 1, 2 and 3

Cardio and metabolic risk assessment

  • Oral glucose tolerance testing
    • A test to determine one’s ability to process glucose in the body.  An OGTT involves consuming  a sugar solution followed by incremental blood draws for 120 minutes.
  • Additional biochemical assays
  • Blood pressure
  • Peripheral arterial tonometry to measure vascular function

Normal and Abnormal response

Measuring energy expenditure

  • Indirect calorimetry using a breathing hood
    • This test measures exhaled CO2/O2 and O2 consumed using a plastic hood that fits over the participant’s head.  These measurements allow us to estimate the amount of energy consumed under sedentary conditions.
  • Doubly labeled water
    • The participant will drink isotope labeled water and will collect urine samples for one week.  By examining the proportion of istotope-labeled water in the urine we can estimate energy consumption during a normal week.
  • Accelerometry and physical activity questionnaire
    • Accelerometry involves wearing a pager sized device for seven days which records the amount and force of movement throughout the week.

Measuring body composition

  • Using the following two procedures, we will measure fat and fat-free mass, intra-abdominal and hepatic fat, and intramyocellular lipids.
    • BODPOD device
  • Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI)

Response to a meal

  • Mixed meal tolerance test
    • The MMT is a test in which the participant consumes a liquid meal replacement and has incremental blood tests to determine the individual's hormonal and metabolic response to meals.

Exercise testing

  • Exercise bike
    • This test involves exercising on a standard stationary bike, while having incremental blood tests done to measure exercise markers and breathing thorugh a mouth piece.  This test allows the researchers to analyze:
      • Anaerobic and aerobic metabolism  
      • Fatty acid oxidation, aerobic capacity, and peak work rate     
  • Exercise in a MRI
    • Allows us to observe:
      • Muscle blood flow
      • Mitochondrial function     

Exercise in a MRI

Read more about Specialty Care research objective