Cosmetic surgery should not be used as a weight loss program. Dr. Tyrone recommends patients reach their weight loss goals prior to surgery in order to have optimal surgical results. BMI can be used to indicate if you are overweight, obese, underweight or normal. A healthy BMI score is between 20 and 25. A score below 20 indicates that you may be underweight; a value above 25 indicates that you may be overweight.