What is obesity and its related BMI

Obesity is a term used to describe somebody who is very overweight, with a lot of body fat.
It's a common problem, estimated to affect around one in every four adults and around one in every five children aged 10 to 11 in the UK.
Defining obesity
There are many ways in which a person's health in relation to their weight can be classified, but the most widely used method is body mass index (BMI).
BMI is a measure of whether you're a healthy weight for your height. You can use the BMI healthy weight calculatorto work out your score.
For most adults:
a BMI of 25 to 29.9 means you are considered overweight
a BMI of 30 to 39.9 means you are considered obese
a BMI of 40 or above means you are considered severely obese
BMI is not used to definitively diagnose obesity – as people who are very muscular sometimes have a high BMI, without excess fat – but for most people, it can be a useful indication of whether they may be overweight.
A better measure of excess fat is waist circumference, and can be used as an additional measure in people who are overweight (with a BMI of 25 to 29.9) or moderately obese (with a BMI of 30 to 34.9).
Generally, men with a waist circumference of 94cm or more and women with a waist circumference of 80cm or more are more likely to develop obesity-related health problems.