A Trial to Investigate the Impact of a Low Glycemic Index (GI) Diet on Body Mass Index and Obesity Related Cardiovascular and Hormonal Factors in Chinese Adolescents

This is a 12-month randomized controlled dietary interventional trial followed by a 6-month observational period. The objectives of this study include:

• To study changes of body mass index, body fat percentage, insulin secretion, insulin resistance and obesity associated cardiometabolic factors;
• To explore underlying neurohormonal mechanisms associated with these changes in both short- and long-term.

Inclusion criteria

• School children aged 15 or above
• Male or female of Chinese ethnicity
• Body mass index >/= 95th percentile of Hong Kong local age- and sex-specific reference
• No major medical illness
• Not on any chronic medications
• Post-pubertal as ascertained by clinical assessment by endocrinologist
• Willingness to give written informed consent by participants and his/her parents/guardian

Exclusion criteria

• Concurrent participation in any clinical trial, dietary intervention or weight loss program
• Concomitant intake of weight reducing agent
• Active and uncontrolled endocrine diseases including hypo- or hyperthyroidism, Cushing's syndrome, diabetes mellitus, etc.
• Significant renal impairment, defined as serum creatinine >150 umol/L and/or estimated glomerular filtration rate <60ml/min/1.73m2
• Significant liver impairment, defined as >2 times upper limit of alanine aminotransferase and asparate aminotransferase levels
• Gastrointestinal problems that would prevent them from following the test diets
• Active malignant disease
• Pregnant or lactating
• Any medical illness or condition including known non-compliance, as judged by the investigators as ineligible to participate the study