Obesity or Overweight? Obesity is a term that seems to get used a lot and in most cases it may not be clear what it means. Does it mean that you are overweight or you just have a few excess pounds to shed? Could it be more than that? To be clear on this topic, there is a medical definition for the term obesity. However, let’s first look at what it is to be overweight to understand it in context: Classifications To be classified as overweight, you will have to record a Body Mass Index (BMI) between 25.0 – 29.9.