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Open Access Highly Accessed Research article

A randomized controlled trial to investigate the impact of a low glycemic index (GI) diet on body mass index in obese adolescents

Alice PS Kong1, Kai Chow Choi2*, Ruth SM Chan1, Kris Lok1, Risa Ozaki1, Albert M Li3, Chung Shun Ho4, Michael HM Chan4, Mandy Sea1, C Jeyakumar Henry6, Juliana CN Chan15 and Jean Woo1

Author Affiliations

1 Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, SAR, China

2 Nethersole School of Nursing, The Chinese University of Hong Kong, Hong Kong SAR, Shatin, N.T., Hong Kong, SAR, China

3 Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong, SAR, China

4 Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong, SAR, China

5 Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, SAR, China

6 Director, Clinical Nutrition Research Centre, Oxford, Singapore

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BMC Public Health 2014, 14:180  doi:10.1186/1471-2458-14-180

Published: 19 February 2014

Abstract

Background

The role of a low glycemic index (GI) diet in the management of adolescent obesity remains controversial. In this study, we aim to evaluate the impact of low GI diet versus a conventional Chinese diet on the body mass index (BMI) and other obesity indices of obese adolescents.

Methods

Obese adolescents aged 15–18 years were identified from population-recruited, territory-wide surveys. Obesity was defined as BMI ≥95th percentile of Hong Kong local age- and sex-specific references. Eligible subjects were randomized to either an intervention with low GI diet (consisting of 45-50% carbohydrate, 30-35% fat and 15-20% protein) or conventional Chinese diet as control (consisting of 55-60% carbohydrate, 25-30% fat and 10-15% protein). We used random intercept mixed effects model to compare the differential changes across the time points from baseline to month 6 between the 2 groups.

Results

104 obese adolescents were recruited (52 in low GI group and 52 in control group; 43.3% boys). Mean age was 16.7 ± 1.0 years and 16.8 ±1.0 years in low GI and control group respectively. 58.7% subjects completed the study at 6 months (65.4% in low GI group and 51.9% in control group). After adjustment for age and sex, subjects in the low GI group had a significantly greater reduction in obesity indices including BMI, body weight and waist circumference (WC) compared to subjects in the control group (all p <0.05). After further adjustment for physical activity levels, WC was found to be significantly lower in the low GI group compared to the conventional group (p = 0.018).

Conclusion

Low GI diet in the context of a comprehensive lifestyle modification program may be an alternative to conventional diet in the management of obese adolescents.

Trial registration number

ClinicalTrials.gov Ref. No: NCT01278563

Keywords:
Glycemic index; Obesity; Adolescents; Chinese