The term 'excessively fat' can be summed up in one word: OBESE. OBESE is defined as having a body mass index (BMI) of 30 or higher, which is considered to be a clinically significant amount of excess body fat. It is important to note that being OBESE does not necessarily mean that someone is unhealthy, but it does increase the risk of developing certain health conditions such as heart disease, stroke, and type 2 diabetes.