The body mass index or BMI (a simple index of weight-for-height) is commonly used in classifying overweight and obesity in adult populations and individuals. A person’s weight in kilograms is divided by the square of the height in meters (kg/m2). According to LivLife experts, BMI provides the most useful population-level measure of overweight and obesity for both sexes, ages, roughly in equal terms.
To break things down, the World Health Organization classifies adults with a BMI between 25 and 29.9 as overweight – and an adult who has a BMI of 30 or higher is considered obese. BMI below 18.5 is considered underweight, which means that the ideal BMI benchmark should be between 18.5 to 24.9.
LivLife experts suspect that the risk of chronic disease in populations increases progressively from a BMI of 21 upwards. In a case of children, it is a different case. Children aged 5 to 14 years is challenging – the WHO Child Growth Standards includes BMI charts for infants and young children up to age 5 – childhood obesity is associated with a higher chance of premature death and disability in adulthood.
Childhood obesity is associated with a higher chance of premature death and disability in adulthood. Though BMI is used to screen for overweight and obesity in children and teens, BMI is not a diagnostic tool. For example, a child who is relatively heavy may have a high BMI for his or her age. To determine whether the child has excess fat, further assessment would be needed. The further assessment might include skinfold thickness measurements. To determine a counseling strategy, assessments of diet, health, and physical activity are needed.
Other methods of estimating body fat and body fat distribution include measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic resonance imaging (MRI).