Guidelines Dietary - Eat For Health

How is healthy weight assessed?Guideline 1The most common approach is the use of the body mass index (BMI) calculated as weight (in kilograms)divided by height (in metres) squared (kg/m 2 ).BMI is a measure of body size that is widely used as an index of relative risk of mortality and morbidityat the population level, with risk lowest in the healthy weight range. 100,104BMI categories for adults are as follows: 104,117• < 18.5 kg/m 2 – underweight• 18.5 to 24.9 kg/m 2 – healthy weight• 25.0 to 29.9 kg/m 2 – overweight• ≥ 30.0 kg/m 2 – obese.However, this classification may not be suitable for all population groups: 118,119• some groups may have equivalent levels of risk at a lower BMI (e.g. people of Asian origin) or higherBMI (e.g. people of Polynesian origin including Torres Strait Islanders and Mãori) 120• while specific BMI ranges have not been developed, Aboriginal people have a relatively high limb totrunk ratio and may have equivalent levels of risk at a lower BMI• a higher BMI range may be desirable for people aged over 70 years.Waist circumference is also used as a proxy for chronic disease risk in adults: 12,121• risk is increased at ≥80 cm and high at ≥88 cm for women and increased at ≥94 cm and high at≥102 cm for men• as with BMI, thresholds for other ethnic groups may differ from those for people of European descent.For children and adolescents, continuing growth means that it is not possible to have a single set ofnumerical values for BMI cut-offs that apply to all ages and both sexes. Weight appropriateness iscommonly assessed using age-related cut-off values 122,123 or Z-scores (or standard deviation scores). 124For more information, see Appendix H.1.1.2 Health effects associated with weight statusAdultsOverweight and obesityOverweight and obesity are associated with increased risk of type 2 diabetes, cardiovascular disease, hypertension,metabolic syndrome, some cancers, musculoskeletal conditions, respiratory conditions, sleep apnoea, gall bladderdisease, hernia, reproductive disorders, urinary incontinence, fatty liver disease, and depression and other mentalhealth disorders. 88,89,98,125 About 70% of people who are obese have at least one established comorbidity, resulting inmedical costs that are about 30% greater than those of their healthy weight peers. 107Compared to having a BMI of 18.5–25 kg/m 2 , having a BMI of 30–35 kg/m 2 reduces life expectancy by 2–4 years,and having a BMI of 40–45 kg/m 2 reduces it by 8–10 years. 126 The relative increase in mortality rate attributable toobesity tends to decline with age. 127 Mortality and morbidity are also associated with the amount of weight gainedin adult life. 89,98,101Many obesity-related conditions are preventable, and several are at least partially reversible through weight lossachieved by adopting a nutritious dietary pattern and active lifestyle. 89,98,101Achieve and maintain a healthy weightNational Health and Medical Research Council13