What is the Definition of Obesity?

Before we start looking at individual organs, it helps to first understand what we actually mean when we say obesity. Clinically, obesity is often defined using a measurement called body mass index or BMI, which compares body weight to height. A BMI of 30 or higher is typically used as the clinical threshold for obesity. Now, BMI does have some limitations. For example, someone with a large amount of muscle mass could technically have a high BMI even though their body fat is relatively low. And since muscle adds weight, BMI can occasionally be misleading in those situations. However, for most people in the general population who don't have unusually high amounts of muscle mass, BMI works reasonably well because in most cases, excess body weight is coming from excess atapost tissue or body fat. And that excess atapost tissue is what drives many obesity related health conditions.