The most common measure used in adults to determine if you are a healthy weight is body mass index (BMI) calculated as weight (kg) /height (m)2. A person is classed as obese if they have a BMI of 30kg/m2 or above.
In childhood, however, constant changes in body composition during growth mean that the relationship between BMI and body fat is age-dependent and further complicated by race and gender. This is why the classification of overweight and obesity in children and adolescents is more problematic than in adults.
Furthermore, BMI does not distinguish between the contribution to body weight of fat tissue and that of muscle, bone and water, nor does it provide any information about where fat is deposited. This is important because there is good evidence that, compared with children only 20 years ago, modern children are much fatter, have less muscle and a more central distribution of body fat – an “apple” as opposed to a “pear” shape. Consistent with the central distribution of body fat, studies of child obesity have shown a significant increase in waist sizes in children, especially in girls. These changes in fat distribution are of particular concern because they are more likely to lead to obesity problems and the well known complications of obesity in adult life such as diabetes, heart disease and cancer.
Enter your Child's Height and Weight to Assess their BMI