What is obesity? (best answer gets 10 points!)?

ok, i know what it it..its when a person is overweight..but could you please supply me with the scientific term and if possible bring up some points on teen obesity?

p.s this is for a project so could you please help :)

Obesity is having a high proportion of body fat. Fat is important for storing energy and insulating your body, among other functions. The human body can handle carrying some extra fat, but beyond a certain point, body fat can begin to interfere with your health. For this reason, obesity is more than a cosmetic concern. Obesity puts you at greater risk of developing high blood pressure, diabetes and many other serious health problems.

Causes:
-Diet.
Regular consumption of high-calorie foods, such as fast foods, or increasing their portion sizes contributes to weight gain. High-fat foods are dense in calories. Loading up on soft drinks, candy and desserts also promotes weight gain. Foods and beverages like these are high in sugar and calories. In general, eating away from home also increases calorie intake.
-Inactivity.
Sedentary people are more likely to gain weight because they don't burn calories through physical activities.
-Quitting smoking.
Smokers tend to gain weight after quitting. This weight gain may be partially due to nicotine's ability to raise the rate at which your body burns calories (metabolic rate). When smokers stop, they burn fewer calories. Smoking also affects taste; quitting smoking makes food taste and smell better. Former smokers often gain weight because they eat more after they quit. However, cigarette smoking is still considered a greater threat to your health than is extra weight.
-Pregnancy.
During pregnancy a woman's weight necessarily increases. Some women find this weight difficult to lose after the baby is born. This weight gain may contribute to the development of obesity in women.
-Certain medications.
Corticosteroids and tricyclic antidepressants, in particular, can lead to weight gain. So can some high blood pressure and antipsychotic medications.
-Medical problems.
Uncommonly, obesity can be traced to a medical cause, such as low thyroid function or excess production of hormones by the adrenal glands (Cushing's syndrome). A low metabolic rate is unlikely to cause obesity. In addition, it's unclear whether polycystic ovarian syndrome contributes to obesity. Some medical problems, such as arthritis, can lead to decreased activity, which may result in weight gain.

For more info check out the website
http://www.mayoclinic.com/health/obesity...

A condition where there is excess body weight due to an abnormal accumulation of fat. Defined objectively as a Body Mass Index (BMI) of 30 or more

By definition, 15% - 20% or more extra body fat. Fat works against the action of insulin. Extra body fat is a risk factor for diabetes, particularly in cats

The condition in which excess fat has accumulated in the body; usually considered to be 20 percent above the recommended weight for height and age.

Obesity:

Women: 33%-35% body fat and/or waist of 35 inches.
Men: 25% body fat and/or waist of 40 inches.

Search google. You will get far more in depth answers and alot more information then most could supply for you here