Obesity indicators and their impact on the cardio-metabolic disease in an Asian-Indian ethnic population
AffiliationMelbourne School of Population and Global Health
Document TypePhD thesis
Access StatusThis item is embargoed and will be available on 2023-07-22. This item is currently available to University of Melbourne staff and students only, login required.
© 2020 Nitin Kapoor
Background: Obesity has attained pandemic proportions globally, including in many South Asian countries. The spectrum of obesity in the Indian setting may vary from apparently thin looking individuals with normal weight obesity (NWO) to those at the far end of the spectrum with morbid obesity. However, several knowledge gaps have been identified regarding the utility of clinical and genetic indicators of obesity, across this spectrum, in this unique population. Aims and Objectives: In this study I explored the prevalence of normal weight obesity (NWO) in a cohort from southern India and studied the cardiometabolic disorders associated with this phenotype. I have evaluated the impact of a peer-led lifestyle intervention in individuals with NWO, at a two-year follow-up and determined the obesity indicators that would best predict metabolic disorders in this population. I have also studied the clinical and genetic indicators of obesity in a cohort of patients with morbid obesity. Material and Methods: The objectives mentioned above, across the spectrum of obesity were studied using two datasets. The first dataset, the Kerala Diabetes Prevention Program, is an ongoing longitudinal cluster randomized study, wherein 3552 study subjects were screened and those recruited were subjected to a peer-led life style intervention and followed up on an annual basis up till two years and hereby planned for a 7 year follow-up. The objectives in individuals with morbid obesity were studied in prospectively recruited individuals, from the Vellore bariatric clinic. All patients, recruited from both the datasets, underwent standardized measurements of obesity indicators, had a rigorous cardiometabolic screening and assessment of body composition which included body fat. The genetic analysis in a subset of young-onset morbidly obese individuals was undertaken using a Next Generation Sequencing (NGS) based protocol covering 35 monogenic causes for obesity. Results: The prevalence of NWO in this population was found to be 32% (95% CI: 29.1-34.5%). Individuals with NWO had a significantly higher prevalence of T2DM, hypertension and dyslipidaemia as compared to those without obesity and similar to those who were traditionally identified with obesity. Two years after a peer led lifestyle intervention, only a slight trend towards a favourable change in systolic blood pressure and HDL cholesterol was noted. Amongst several clinical obesity indicators that were studied, waist-height ratio and waist-hip ratio were most significantly associated with cardio-metabolic complications. METS-VF (Metabolic score for visceral fat), a novel obesity indicator, was validated in the Indian population and found to be a good predictor of visceral adipose tissue among individuals with morbid obesity. Sixteen percent of individuals with young onset morbid obesity were found to have a monogenic aetiology for obesity. Conclusion: The obesity phenotype in India differs significantly when compared to other populations. A significant proportion of people have normal weight obesity, which is associated with a high prevalence of cardiometabolic disorders and had minimal trend towards improvement following a two-year life-style intervention. In this setting, the utilization of surrogate measures that predict visceral adiposity and screening for monogenic disorders with NGS in those with young-onset morbid obesity, may be useful adjuncts in the evaluation of obesity in this population.
KeywordsSouth Asian phenotype; Obesity Indicators; Monogenic obesity; Normal weight obesity; Thin-fat phenotype; Peer led lifestyle intervention
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