Obesity is a condition where a person has accumulated so much body fat that it might have a negative effect on their health. It can be described as the condition or situation which results from excess storage of fat in the human body.

Obesity can also be explained as the condition of a body to gain weight more than what the body required or normal according to the body weight, age or height.

For example: If a person's bodyweight 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.

Obesity is excess fat and should be avoided with extreme measures to stay fit. The body weight can be calculated using BMI which is also known as Body Mass Index. This will help you calculate your body weight and can determine if you are actually gaining weight or becoming obese.

What is Body Mass Index (BMI)?
The body mass index (BMI) is a statistical measurement derived from your height and weight. Although it is considered to be a useful way to estimate healthy body weight, it does not measure the percentage of body fat. 

The higher the BMI, the more obese a person is while the lower the BMI, the lower the obesity of an individual which applies to either men or women, children or teenagers..
You can calculate Body Mass Index using the below formula;

BMI  =  Weight (kg)  =  kg
            Height (m)        m

Conversion Factor;

Pounds  =  kg

The healthy weight range from BMI 18.5 to 22.9

If your BMI is < 18.5                                  then you are underweight
If your BMI is within the range 18.5 - 22.5    then you are normal
If your BMI is > than 22.5  then                   You are overweight or Obese

These is the formula that tells you if you are obese or you are getting obese.

Read : 
(Photo) Medical Complications of Obesity

Note: Obesity is not good for the body,  you need to get rid of it very fast.