EAT FOR HEALTH Australian Dietary Guidelines

EAT FOR HEALTH – AusTRALiAn diETARy guidELinEs

14

Guideline 1

Underweight

While the greatest risk to health on a population basis is associated with being overweight, being underweight

can also have adverse health consequences including decreased immunity (leading to increased susceptibility to

some infectious diseases), osteoporosis, decreased muscle strength and hypothermia.^36 Among older people,

being underweight may be more deleterious to health than being overweight.^128

Inappropriate dietary restriction and eating disorders occur in some adults.^129

Children and adolescents

Overweight and obesity

The most immediate consequences of overweight and obesity in childhood are social discrimination (associated

with poor self-esteem and depression), increased risk of developing negative body image issues, and eating

disorders.101,130 Overweight children and adolescents are more likely to develop sleep apnoea, breathlessness

on exertion and reduced exercise tolerance, some orthopaedic and gastrointestinal problems, non-alcoholic fatty

liver disease, and early signs of metabolic and clinical consequences, such as hypertension, hyperinsulinaemia,

hypertriglyceridaemia and type 2 diabetes.101,130

A major long-term consequence is that overweight children are more likely to become overweight or obese adults,

with an increased risk of chronic diseases and early mortality.101,130-132 The risk of chronic disease is increased with

rapid weight gain in infancy and early childhood.88,89

Underweight

In infancy and early childhood, underweight and failure to thrive can be more prevalent than overweight and

obesity in some communities. Failure to thrive is most commonly a result of socioeconomic factors, including

poor living conditions^133 but can also occur among affluent sections of the community due to inappropriate

dietary restrictions (e.g. based on fears about ‘unhealthy’ dietary habits).^134 Specialist advice should be sought

on underweight and failure to thrive in infants and children (for further information on growth see Appendix H).

Inappropriate dietary restriction and eating disorders occur in some adolescents.^129

1.1.3 Causes of overweight and obesity in the population

Healthy body weight results from an appropriate balance between energy intake and expenditure (of which

physical activity is a component).89,101,135 At the population level, there is increasing evidence that excess energy

intake is a major contributor to energy imbalance.88,135-140

The obesogenic (obesity promoting) environment

Excess weight gain is directly and indirectly influenced by a wide range of factors, including inherited biological

factors and early life experiences, as well as behavioural, environmental and social factors that influence individual

behaviours. The relationships between these factors are complex and not yet fully understood.

Although genetic factors may increase an individual’s susceptibility to being overweight or obese, the dramatic

increase in prevalence of overweight and obesity over the past few decades suggests that socioenvironmental

factors are a major contributor to the current epidemic.88,89,98,101,138,139,141 Significant changes during this period

include, but are not limited to:

•   changes in the food supply, particularly increased availability and decreased relative cost of foods which tend

to be higher in energy density and relatively nutrient-poor^142

•   increased availability and marketing of energy-dense, nutrient-poor foods and drinks

•   urban design which reduces energy expenditure during daily activities and increased reliance on car and

labour-saving devices138,143

•   reduced perceptions of safety leading to fewer opportunities for physical activity144,145

•   economic and consumer changes, such as a greater number of women in the paid workforce, decreased

food literacy and cooking skills, and greater reliance on convenience and takeaway foods.140,141,146