Obesity is a condition where a person has accumulated so much body fat that it might have a negative effect on their health. About one-third of US population suffer from obesity. If a person’s body weight is at least 20% higher than it should be, he or she is considered obese. If your Body Mass Index (BMI) is between 25 and 29.9 you are considered overweight. If your BMI is 30 or over you are considered obese.