Understanding Body Mass Index (BMI) as a Measure of Body Fat and Health Indicators

1. Our Measure of Body Fat: The Body Mass Index (BMI) What Is Body Mass Index? Body Mass Index (BMI) is a proxy measure of a person’s body fat. It is based on their weight and height (more specifically, their body mass divided by the square of their height), so it does not actually involve measuring their percentage of body fat. BMI values are usually written as kg/m². Using this value, the individual can be categorized into one of eight groups, defined by the World Health Organization: Very severely underweight <15.00 kg/m². Severely underweight 15.00-16.00 kg/m². Underweight 16.00-18.50 kg/m². Normal (healthy) weight 18.50-25.00 kg/m². Overweight 25.00-30.00 kg/m². Moderately obese 30.00-35.00 kg/m². Severely obese 35.00-40.00 kg/m². Very severely obese >40.00 kg/m². Why Are We Measuring BMI In Our Study? BMI is an important physical health indicator. The extent of a person’s body fat plays a large role in predicting various health problems, such as heart disease and stroke. We intend to investigate the effect of group identification on BMI over time, using a longitudinal study design. As noted earlier, BMI is only a proxy measure, which means that it is not a perfect indicator of body fat levels. For instance, people who are very athletic and muscular may be categorized as obese, even though they are actually more likely to have a very low body fat percentage. For this reason, we are measuring two other useful health indicators: cholesterol and blood pressure. We expect these three measures (in combination) to provide us with a good indication of our participants’ physical health. How Are We Measuring BMI In Our Study? BMI is one of the measures we are obtaining through the health data stored by each participant’s GP. We will obtain each participant’s most recent measure of height and weight from their medical file, and use these to calculate their BMI. For More Information: Email Prof. Fabio Sani: f.sani@dundee.ac.uk