Body Mass Index as a measure of obesity

This Q and A style briefing paper provides an overview of the use of body mass index (BMI) for the measurement of obesity. BMI is a person’s weight in kilograms divided by the square of their height in metres. It is one of the most commonly used ways of estimating whether a person is overweight and hence more likely to experience health problems than someone with a healthy weight. It is used to measure population prevalence of overweight and obesity. It is also a relatively easy, cheap and non-invasive method for establishing weight status. However, BMI is only a proxy for body fatness. Factors such as fitness, ethnic origin and puberty can alter the relation between BMI and body fatness and must be taken into consideration. Other measurements such as waist circumference and skin thickness can be collected to indicate a person’s weight status or body fatness. None of these is as widely used as BMI.

Changes in children’s body mass index between 2006/07 and 2013/14 National Child Measurement Programme

This report is the sixth in a series of annual reports which use National Child Measurement Programme (NCMP) data to examine changes in children’s body mass index (BMI) that have taken place since 2006/07. It explores trends in obesity, overweight, excess weight and underweight prevalence, as well as changes in mean BMI over time. Trends within different socioeconomic and ethnic groups are also examined to determine whether existing health inequalities are widening or becoming smaller.