Investigations into obesity using anthropometric, serum and genetic markers

• Main Author: Kennedy, Aaron P.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2010
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/8840/; https://research.library.mun.ca/8840/1/Kennedy_Aaron.pdf

Obesity is one of today's most visible public health problems with worldwide incidence at over a billion people. To understand such a vast problem requires one to study the issue from different angles. This includes studying how obesity is measured, and how metabolic and genetic factors influence the obesity phenotype. This thesis investigates the accuracy of the body mass index, a trusted measurement tool, compared to an industry standard measuring tool DXA. It also investigates the effects of serum calcium on serum lipid levels and how polymorphisms in two genes associated with the storage of fat in the human adipocyte affect obesity phenotypes. -- Although body mass index (BMI) is the most widely used measure of obesity, debate still exists on how accurately BMI defines obesity. In this study, adiposity status defined by BMI and DXA were compared in a large population to evaluate the accuracy of BMI. A total of 1691 adult volunteers from Newfoundland and Labrador (NL) participated in the study. BMI and were measured for all subjects following a 12 hour fasting period. Subjects were categorized as underweight (UW), normal weight (NW), overweight (OW), or obese (OB) based on BMI and criteria. Differences between the two methods were compared within gender and by age groups. According to BMI criteria 1.2% of women were classified as UW, 44.4% as NW, 34.1% as OW and 20.3% as OB. When women were classified according to criteria 2.2% were UW, 29.7% were NW, 31.0% were OW and 37.1% were OB. The overall discrepancy between the two methods for women was substantial at 34.8% (14.6 % for NW and 16.9% for OB, p<0.001). In men the overall discrepancy was 35.2% between BMI and DXA (17.6% for QW and 13.5% for OB, p<0.001). Misclassification by BMI was dependent on age, gender and adiposity status. In conclusion, BMI misclassified adiposity status in approximately one third of women and men compared with DXA. Caution should be taken when BMI is used in clinical and scientific research as well as clinical practice. -- ...