An Investigation into the prevalence of Normal-Weight Obesity Syndrome among Caucasian Adults Residing in Scotland

Abstract

Introduction: Body mass index (BMI) is the most commonly used parameter to measure nutritional status in adults. Recently, it has been discovered individuals can have a BMI within normal range but excess body fat (BF), this is known as Normal-Weight Obesity Syndrome (NWO). These individuals have a healthy BMI, however, are at risk of the same health risks as those with a BMI in the obese range such as cardiovascular disease and insulin resistance. The prevalence is not well established but can range from 5% to 45%. Hypothesis: NWO does exist in Caucasian adults residing in Scotland at an expected prevalence of approximately 10%. Method: A cross sectional study involving a voluntary sample of Caucasian adults aged 18-75 years old with a normal BMI (18.5-24.9 kg/m2). Basic anthropometric measurements such as weight and height were taken. Body fat percentage (BF%) was measured via bioelectrical impedance analyser (BIA). A 3-day diet diary was self-reported and a non-exercise VO2max questionnaire was answered. NWO was defined as normal BMI with a body fat percentage ≥30% for females and ≥23% for males. Results: Forty-two participants, (eleven males and thirty-six females) participated in the study. The mean age was 24.05 years (±7.03) and a mean BMI of 22.67 kg/m2 (±1.55). The prevalence rate of NWO was 14.29% (n=6). Statistical analysis showed there was a significant difference between BF% and BMI (p=0.009). BF% positively correlated with height (r=-0.983, p<0.001) and weight (r=-0.927, p<0.001); VO2max was inversely correlated with BF%; macronutrient intake correlated negatively with body fat percentage in normal-weight obese participants (p<0.001). Conclusion: This is the first study in the UK examining the relationship between BMI and NWO within the Scottish population. It confirms, alongside previous research that NWO occurs moderately within population. A larger-scale prospective cohort study may give a greater insight into the prevalence of NWO in Scotland and how diet and physical activity levels influence this syndrome. Key Words: Normal-Weight Obesity; bioelectrical impedance; body mass index; body fat percentage; obesity.