MICHAEL LAMBERT. Overweight and Obesity Part 1: A Global and Australian Perspective03/01/2018
In part 1 of this two-part post Michael Lambert sets out the broad position on overweight and obesity as both a global development and the Australian situation, the costs involved and the case for national action . The second part of this post will focus on the position with indigenous Australians, its contribution to the health gap between indigenous and non-indigenous Australians and the need for action to target overweight and obesity in indigenous children and adolescents.
The pandemic of overweight and obesity is global, affecting developed countries, developing countries and, increasingly, lower income countries. It is part of a broader trend of the increasing prevalence of non -communicable chronic diseases which now account for more than 70 per cent of health expenditure globally and has a major negative impact on living standards and the economy.
The prevalence of overweight and obesity started to increase in the 1970s in developed countries and subsequently spread to developing countries. Hence its origins are global in nature. All the evidence points to the increase in overweight and obesity being associated with major changes in the food system with increased availability and declining real prices of energy dense, nutrition poor (EDNP) food and beverages. This interacted with a longer term trend, apparent since the beginning of the 20th century, of reduced level of physical activity in work and the personal spheres. This trend did not initially lead to increased obesity as, based on US data, there had been up to the 1970s a corresponding decline in the energy intake of food consumed. This changed in the 1970s forward with the mass production, distribution and consumption of EDNP food and beverages and the development of what are termed obesogenic environments, environments that promote obesity.
The take-off in the level of overweight and obesity occurred in developed, high income countries in the 1970s and 1980s and then subsequently spread to most middle income and many low-income countries.
There are variances around this global trend such as:
- higher levels of obesity in lower socioeconomic groups and in societies with higher levels of inequality;
- more pronounced levels of obesity in urbanised societies and also influenced by the forms of transport in place, with greater obesity associated with less reliance on active and public transport;
- globally more severe amongst indigenous peoples relative to the relevant non-indigenous population, in line with the global tendency for relatively poorer health status of indigenous peoples.
Australia has a relatively high level of overweight and obesity compared to other developed countries with 63 per cent of adults and 27 per cent of children classified as overweight or obese and with an upward trend. Compared with other countries in the OECD, Australia has the fifth highest level of obesity, ranked after the USA, Mexico, New Zealand and Hungary, in that order.
The problem of overweight and obesity impacts across all ages and cultural backgrounds, though not equally. This is well documented by the Australian Institute of Health and Welfare. The key facts are as follows.
Children and adolescents
- In 2014-15, 27 per cent of children and adolescents aged 5-17 were overweight or obese, with 7 per cent obese.
- For children aged 2-4, 20 per cent were overweight or obese.
- Children and adolescents in 2014-15 were significantly more likely to be overweight or obese at ages 10-13 and 14-17 than their counterparts of 20 years ago, by a factor of about 1.5 (i.e. the incidence now is 1.5 times the incidence of 20 years ag0). For obesity for children aged 2-4 the factor was 2.25.
- The incidence of overweight and obesity for children and adolescents in the lowest socio economic group compared to the highest socioeconomic group was a factor of 1.5.
- Indigenous adolescents aged 15-17 had a higher level of overweight or obesity, at 35 per cent, compared to non-indigenous adolescents of the same age at 24per cent and had double the rate of obesity.
- In 2014-15 63per cent of adults were overweight or obese (28 per cent obese), with men having a higher overall rate (71 per cent) than women(56 per cent), though the rate of obesity was similar (28 per cent for men versus 27 per cent for women).
- After adjusting for changes in age structure of the population, prevalence of overweight or obesity rose from 57 per cent in 1995 to 63 per cent in 2014-15.
- Overweight and obesity increases with remoteness and is higher for adults living outside major cities.
- Indigenous adults had a higher rate of overweight and obesity at 69 per cent but particularly had higher rate of obesity at 40 per cent versus 28 per cent for non- indigenous adults, a higher rate of 1.4; 36 per cent of indigenous men were obese and 43 per cent of women. After adjusting for age structure differences indigenous adults were 1.2 times as likely to be overweight or obese and 1.6 times as likely to be obese.
- 46 per cent of women who gave birth were overweight or obese, with obesity during pregnancy contributing to higher morbidity and death for mothers and babies.
Key behaviours driving the trend include poor nutrition, with excess consumption of EDNP food and beverages and low levels of physical activity. Overweight and obesity in turn increase the risk of developing cardiovascular disease, high blood pressure, type 2 diabetes, chronic kidney disease and certain types of cancer.
The key behaviours driving this trend are poor diet and inadequate levels of physical activity as evidenced by the following statistics drawn from ABS health surveys:
- Australians on average have 35 per cent of their total daily energy consumption in the form of discretionary food, with the intake being lowest for 2 to 3 year olds (30 per cent) and highest for 14 to 18 year olds (41 per cent). Discretionary foods do not belong to the five base food groups, are not necessary for a healthy diet and are EDNP foods, high in saturated fat, added sugars, salt and low in fibre.
- One third of Australians regularly consume sugar sweetened beverages (SSB), including 47 per cent for 2 to 18 year olds and 31 per cent for adults. Medium daily consumption is about 375 ml per day and 47 per cent of Australians who are overweight or obese consume SSB regularly. With respect to indigenous Australians 56 per cent regularly consume SSB with the average daily consumption being 455ml.
- In 2011-12, Australians consumed an average of 60 gm of free sugar per day (about 14 teaspoons) with 52 per cent coming from SSB.
- Four out of five Australian children and almost one sixth of adults do not meet the national minimum recommendations for physical activity, noting that the minimum recommendation for adults is only 30 minutes per day of moderate physical activity.
In addition to the health impacts of overweight and obesity in childhood, childhood obesity is a significant risk factor in adulthood. A study has shown a significant association between obesity in children aged 12 to 18 and an increased incidence of diabetes, coronary heart disease and certain cancers in adulthood. It should be noted that there are no diseases found to be linked to overweight and obesity in children younger than 5.
The diseases accounting for the most health burden due to overweight and obesity are cardiovascular disease, accounting for 38 per cent of the burden of disease, followed by a collection of cancers on 19per cent and diabetes on 17 per cent.
If current trends continue there will be approximately 1.75 million deaths in people over the age of 20 years caused by overweight and obesity between now and 2050, with an average loss of 12 years of life for each person who dies before 75 years.
The AIHW has demonstrated that there is a clear socioeconomic dimension to the incidence of overweight and obesity (and indeed to chronic diseases in general), reporting that the lowest socioeconomic group experiences rates of overweight and obesity burden that are 2.3 times those of the highest socioeconomic group, after taking account of different age structures for the two groups. In fact, there is a clear inverse relationship between the level of the socioeconomic group and the burden of disease attributable to overweight and obesity, with the burden increasing systematically from highest to lowest socioeconomic groups.
Various studies have demonstrated that on a conservative basis overweight and obesity has an annual cost of at least $10 billion per annum, split half in health costs and half in lost productivity.
It needs to be recognised that there are barriers to undertaking effective prevention action, evidenced by the very slow progress in counteracting the obesity pandemic. Some of the key barriers are as follows:
- Obesity is a function of the interaction of biological, behavioural, and environmental factors. Complexity of the causes of obesity and the mechanisms by which the pandemic operates as well as the linkage from the condition of obesity to the various related chronic diseases means that any solution needs to be multi- faceted and this complexity acts as an impediment to effective action. This is in contrast, for example, to tobacco smoking.
- There is a relatively long period before there is a discernible population impact from prevention and remedial actions. Modelling has shown that the bodyweight response to a change of energy intake is slow, with a half time of about one year. From the point of view of governments, a long-time lag between action and result is highly problematic.
- An argument is often run, particularly by libertarians, that government does not have a role to intervene in the market to influence or restrict consumer/citizen choice, that consumers/citizens should be free to make decisions as long as their decisions do not inflict harm on others.
Despite these factors, there is a strong case for government prevention action provided that it is evidence-based and assessed as both effective and cost effective. Action is particularly justified in cases where there is market failure. Key considerations for supporting government action in this area include the following:
- There is a need to protect vulnerable persons, specifically children, who do not have the knowledge or ability to make informed choices.
- There is strong evidence that humans are predisposed to put on weight and until recently the environment constrained this tendency, which is no longer the case.
- Consumers in general do not have the information to make fully informed decisions about food selection.
- There is evidence of irrational behaviour in the form of prioritisation of immediate satisfaction over long-term harmful effects.
- There is a strong tendency towards overweight and obesity by people in lower socioeconomic groups which appears to reflect environmental and economic factors rather than the outcome of free, informed choices.
- The costs of obesity are borne by society and is preventable. There are both the direct health costs involved and in addition the broader costs of income support and social security, lower earnings and productivity.
The strongest argument for intervention for prevention purposes applies to children on both ethical and effectiveness grounds:
- Infants are generally not born overweight/obese and hence it is easier to maintain a healthy weight from an early age then at a later stage seek to reduce weight.
- Health risk behaviours and weight status tend, beyond a certain age, to remain relatively stable over life and hence achieving healthy weight and health behaviours in early life will reduce the chances of problems in later life.
- There is an intergenerational benefit in addressing the problem at an early age as, to the degree, the intervention is successful in reducing overweight and obesity in children and adolescents, the benefit will flow into future generations.
- Early childhood is a critical period for social, physiological and psychological development.
- Children are not in a position to make informed choices.
There is in effect a triple benefit in targeting children and adolescents, these being:
- Benefit 1: it is easier to avoid overweight and obesity from an early age then seek to address the problem in later years.
- Benefit 2: the benefit will apply across a full lifetime and will be easier to maintain than a later life intervention.
- Benefit 3: an intergenerational benefit is produced with the normal weight children and adolescents more likely to produce and maintain normal weight children.
The second post will focus on the indigenous Australian dimension of this major health problem.
Michael Lambert is a former Secretary of NSW Treasury and a director and senior adviser on health economics at the Sax Institute, a not for profit organisation that seeks to connect health research with health policy and programs to enhance population health.