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].
Figure 1.6 The McKinsey Global Institute’s economic analysis of the social burdens generated by human beings. Obesity is one of the top three social burdens.
(Source: Reproduced from Dobbs et al. [79].)
Thinking about the economics of obesity is valuable as it alters the frame for decision‐making. Thus, for example, the prevention of childhood obesity, although valuable in itself, does not have a significant impact in preventing the cost of diabetes for about 40 years, whereas a marked reduction in overweight/adults with obesity by getting adults to lose at least 15% of their weight leads to a rapid economic gain as set out by the UK’s Chief Scientist’s inquiry into obesity [77]. This finding has been amplified by Lean and others’ new demonstration of the marked impact on diabetes of inducing at least a 15% weight loss with continuous very‐low‐calorie diets – 85% of recently diagnosed patients with diabetes return their glucose status to near normal levels [78].
Finally, the overall societal costs of overweight and obesity have been assessed on a global basis by the McKinsey Global Institute [79]. Their overview is summarized in Figure 1.6, which reveals the global costs of about $2 trillion per year – nearly equivalent to the cost of all global warfare and terrorism as well as the cost of smoking.
Conclusions
Although obesity has been recognized for millennia as a clinical syndrome, it is only since the 1980s that there has been an explosion of cases worldwide linked to dramatic industrial developments. The burden for physicians is overwhelming, and overweight and obesity per se now constitutes a grave economic and medical burden. This is why radical approaches are now needed to reduce the clinical consequences.
References
1 1. Bray GA. Historical framework for the development of ideas about obesity. In: Bray GA, Bouchard C, James WPT (eds) Handbook of Obesity, 1st edn. New York: Marcel Dekker Inc., 1997:1–30.
2 2. Rasmussen N. Fat in the Fifties: America’s First Obesity Crisis. Baltimore: Johns Hopkins University Press, 2019.
3 3. James WPT (Compilor). Research on Obesity. A Report of the Department of Health and Social Security/Medical Research Council Group. London: HMSO, 1976.
4 4.
