Obesity is when a person is carrying too much body fat for their height and sex. A person is considered obese if they have a body mass index (BMI) of 30 or greater (calculate my BMI).

Today’s way of life is less physically active than it used to be. People travel on buses and cars, rather than walking, and many people work in offices, where they are sitting still for most of the day. This means that the calories they eat are not getting burnt off as energy. Instead, the extra calories are stored as fat.

Over time, eating excess calories leads to weight gain. Without lifestyle changes to increase the amount of physical activity done on a daily basis, or reduce the amount of calories consumed, people can become obese.