Healthy body weight results from an appropriate balance between energy intake and expenditure (of which physical activity is a component).
At the population level, there is increasing evidence that excess energy intake is a major contributor to energy imbalance.
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.
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
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 devices
Reduced perceptions of safety leading to fewer opportunities for physical activity
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.
These changes contribute to an ‘obesogenic’ environment, which promotes excess weight gain by fostering consumption of energy-dense and relatively nutrient-poor foods and/or reduced physical activity.
In the context of this social and physical environment, overweight and obese individuals need support, rather than criticism and discrimination.
Education has an important role in establishing health behaviours and the readiness of individuals to effect behavioural change.
Healthy weight initiatives must achieve a balance between individual and societal responsibility and be culturally appropriate, widely available and accessible, particularly to disadvantaged and vulnerable groups.