The assessment of obesity: methods for measuring body fat and global prevalence of obesity

Fat is a normal component of the human body that is stored in adipose tissu e. Obesity can be defined as a condition of excessive fat accumulation to t he extent that health and well-being are affected. Body fat can be determin ed in vivo in different ways, using rather accurate laboratory techniques o r using simple estimation techniques that can also be applied in field cond itions. For population studies, the World Health Organization defines cut-o ff values for obesity based on the body mass index (BMI): weight/height squ ared (kg/m(2)). Generally, for adults, if the BMI exceeds 25 kg/m(2), a sub ject is considered to be overweight, and if the BMI exceeds the value of 30 kg/m(2), a subject is considered obese. However, the relationship between body fat percentage and BMI differs between ethnic groups, and, as a conseq uence, cut-off points for overweight and obesity based on BMI will have to be ethnicity specific. This means that, in some populations, the cut-off po ints could be lower or higher than the recommended figures. Adapting cut-of f point values will have important consequences for prevalence data in some countries as the prevalence of obesity will dramatically increase or decre ase. The prevalence of obesity, in children as well as in adults, is high i n many countries all over the world and is rising. Given the impact of obes ity on health, this is a public health issue that needs to be addressed ser iously.