In order to understand this section on weight loss surgery you need to know the different types of weight categories. The most scientific method of categorizing someone is the usage of the Body Mass Index (BMI). The BMI is a ratio of your height to your weight. The higher your BMI the worse your weight problem is.
| BMI | |
| < 20 | Underweight |
| 20≤ >25 | Normal Weight |
| 25≤ >30 | Overweight |
| 30≤ >40 | Obese |
| ≥40 | Morbidly Obese |
