Globalization, modern food supply chains, advanced food processing techniques, and ever more sophisticated and aggressive marketing approaches have created a modern food environment that Swinburn et al. [70] have termed obesogenic (literally designed to induce obesity). The current food supply and consumption patterns are dominated by the wide availability of ultra‐processed food products that are highly palatable, cheap, convenient, long‐lasting, and heavily promoted. A high level of consumption of these products replaces core foods (such as fresh fruits and vegetables, meat, milk, and wholegrain cereals). Modern lifestyles have also led to changes in eating and lifestyle behaviors. We have fewer formal meals, we eat in front of the TV, we take away more food rather than cook it at home, and at home, we rely more on ready‐prepared foods. These behaviors are associated with poorer diet quality. Food is also now cheaper and more widely available than it has been at any point in human history, and the portion size of a single serving has increased dramatically. In addition, we are encouraged by marketing to consume even when we are not hungry. Many of these issues are addressed in later chapters.
So we can conclude that major industrial developments have reduced the need for energy expenditure, but the normal physiological adaptive lowering of food intake to match this new lower requirement is counterbalanced by intense food marketing. Furthermore, the greater weight and energy requirements of the obese frame mean, for example, that in the United States, the food industry is profiting from the extra food purchases required to maintain the population with obesity. This has been estimated to amount to many hundreds of billions of dollars of extra sales each year if one considers the excess food eaten by children with obesity both in childhood and then in their adult life [71] plus the extra food sales for adults with obesity.
The burden of obesity
For some time, clinicians have recognized that people with obesity have a great deal of backache and are far more prone to osteoarthritis of the weight‐bearing joints. It was also well known that weight gain exacerbates hypertension and hypercholesterolemia as well as promoting glucose intolerance and then diabetes. These hazards of obesity were usually presented as a consequence of self‐inflicted weight gain, so they were not taken seriously by many clinicians and were even viewed as a means by which one could persuade patients to be slim. However, a more considered understanding of the role of obesity in health was obtained from the WHO Millennium Review of Health conducted by Alan Lopez with Chris Murray and colleagues, which summarized for the first time the amount of death and disability in each of the 14 subregions of the world that was attributable not to particular diseases but to avoidable risk factors. This allowed for much more meaningful public health policy making and led in 2002 to WHO’s report on reducing risks globally [72]. The risk factors considered included iron deficiency anemia and vitamin A deficiency as well as childhood and maternal malnutrition, high cholesterol levels, and high blood pressure. The IOTF was asked to undertake the work on global rates of overweight and obesity for this analysis. The relationship of obesity with a host of other diseases, for example arthritis, cardiovascular disease, cancers, and diabetes, was quantified, and all these relationships together with all the other risk factors were linked to data on premature death (i.e. <75 years) and to years of disability. In this analysis, overweight and obesity were ranked the 7th most important risk factor for premature death on a global basis and the 10th most important factor in terms of disability [73]. Since then, overweight and obesity prevalences have escalated, and Murray’s team based in Seattle with Gates Foundation support has established an annual analysis of disease burden and risk factors which are published regularly by The Lancet. The assessment of the burden of disease in 2017 found a 43% increase in the global male prevalence of overweight (i.e. BMI 25+) from 1990, and in women, the increase was 67% [74]. More detailed analysis of obesity per se came from a special sub‐study with the burden being calculated again as a composite of years of life lost because of weight gain and years of life lived with disabilities linked to excess weight, as shown in Figure 1.5 [75]. Note that the figures include both years of life lost and the years of earlier disabilities. The greatest burden arises from the excess cardiovascular disease induced by excess weight gain, with kidney disease and diabetes being the next two major burdens. However, the authors recognize that the risk increases from about a BMI of 20, and the major finding is that a substantial burden is induced by just being overweight and not obese. In fact, the overweight burden amounts to about a third of all the burden of obesity and actually accounts for nearly 40% of premature deaths related to excess weight gain. This means that in public health terms, one cannot forget about the large proportion of adults who are overweight. Even with modest increments of risk, their high prevalence means that the overweight group contributes a substantial disease burden.
Figure 1.5 The global burden of disease assessed in terms of disability‐adjusted life years (DALYs) in millions, which includes the years of life lost due to premature mortality plus the years lived with a disability from the range of different disorders listed.
(Source: Redrawn from Figure 1.3b in the global burden analyses [75].)
The economic impact of excess weight gain
Given this burden of obesity‐related disease identified in these analyses, policy makers asked obesity specialists to assess the financial damage done by gaining excess weight. These costs are composed of both direct healthcare costs and indirect costs to the community. Although people with obesity have higher rates of illness, the overweight nonobese group still makes a very substantial contribution to the overall hospital and general community cost of general medical care in the community because they make up a much larger proportion of the patient population. Lost productivity associated with failure to attend work because of back pain or other ailments precipitated by the excess body weight together with the loss of efficiency in those who attend work but are unable to work to their maximal capacity also need to be factored into the costings. Many countries have now undertaken an analysis of the costs of obesity to the economy, and it has proved to be alarmingly high. For example, overweight and obesity were responsible for 7% of the total health burden in Australia in 2011 and was estimated to have cost the Australian economy $8.6 billion, with the largest contribution coming from lost productivity [76].