HealthStats NSW
HealthStats NSW
HealthStats NSW
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  • + : Overweight or obesity

    High body weight as a health risk factor

    There are health problems associated with being either underweight or overweight. Although underweight can be a serious risk to health (leading to malnutrition and other health problems such as osteoporosis), public health focus is on excess body weight, as this is a much greater problem in the Australian population.

    Excess weight, especially obesity, is a risk factor for cardiovascular disease, Type 2 diabetes, some musculoskeletal conditions and some cancers. As the level of excess weight increases, so does the risk of developing these conditions. In addition, being overweight can hamper the ability to control or manage chronic disorders.

    Excess weight in children increases the risk of poor health, both during childhood and later in adulthood. Children who are overweight or obese are at greater risk of developing chronic conditions such as asthma and Type 2 diabetes and may experience negative social and mental wellbeing.

    Body Mass Index (BMI)

    High and low body weight categories are determined using Body Mass Index (BMI). BMI is calculated by a person’s weight in kilograms divided by the square of their height in metres (kg/m2). A person considered overweight or obese has a BMI of at least 25 kg/m2. For more details on the BMI, see the Methods section.

    For persons aged 18 years and over, the body weight categories are: underweight (BMI less than 18.5), healthy weight (BMI from 18.5 to 24.9), overweight (BMI from 25.0 to 29.9) and obese (BMI of 30.0 and over). Obesity was further classified into: Obesity Class I (BMI between 30.0 and 34.9), Obesity Class II (BMI between 35.0 and 39.9) and Obesity Class III (BMI of 40.0 or over).

    For children and adolescents, while the same categories to describe body weight are used, the BMI range for each category varies by individual year of age of the child and is different for boys and girls. These category ranges comply with an international standard (Cole et al. 2000; Cole et al. 2007).

    High body weight interventions

    The NSW Healthy Eating and Active Living Strategy 2013-2018 provides a whole of government framework to promote and support healthy eating and active living in NSW and to reduce the impact of lifestyle-related chronic disease.

    The Strategy has four key strategic directions:

    • Environments to support healthy eating and active living;

    • State-wide healthy eating and active living support programs;

    • Healthy eating and active living advice as part of routine service delivery; and

    • Education and information to enable informed, healthy choices.

    Useful websites:

    8700 Find Your Ideal Figure. Available at

    Australian Bureau of Statistics at

    Australian Institute of Health and Welfare at

    Cole T, Bellizzi M, Flegal K, Dietz W. Establishing a standard definition for child overweight and obesity worldwide: International survey. British Medical Journal 2000; 320. Available at (accessed 12 January 2016).

    Cole Y, Flegal K, Nicholls D, Jackson A. Body mass index cut offs to define thinness in children and adolescents: International survey. British Medical Journal 2007; 335(7612): 194. Available at (accessed 12 January 2016).

    Get Healthy Information and Coaching Service. Available at

    Healthdirect at

    Healthy Eating Active Living. Available at

    Healthy Kids, a collaboration between the NSW Ministry of Health, Department of Eduction and Training and the Heart Foundation. Available at  

    Making Healthy Normal. Available at

    National Health and Medical Research Council. Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia. Melbourne: National Health and Medical Research Council, 2013. Available at