1 Obesity – Introduction: History and the Scale of the Problem Worldwide
W. Philip T. James1 and Tim Gill2
1 Department of Population Health, London School of Hygiene and Tropical Medicine, London, UK
2 Boden Initiative, Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
Obesity is a complex condition and, although much remains to be elucidated, our understanding of the many facets of overweight and obesity has advanced greatly over the last few decades. Current research is often focussed on the genetic and molecular patho‐physiological drivers which derange energy balance and lead to excess body fat, but it is important that clinicians have an appreciation of the history and context of these findings and an awareness of the significant challenges created by the different features of obesity that continue to be revealed. Different patterns of obesity emerging across the world may also have different impacts on the public health burden and may require a different approach to the development of prevention and treatment strategies.
The condition of obesity has been recognized for millennia, and its historical context was described in detail by George Bray [1], who highlighted the representation of obesity in images and figurines produced in Europe about 23,000–25,000 years ago. These ancient individuals may well have had a severe form of genetic obesity, and Bray suggests that they may have been considered deities – this would not have seemed unreasonable in societies constantly striving to avoid food shortages. This predicament might still have applied to the general population in the early agricultural period 5000–6000 years BC in Mesopotamia and later in Egypt, but by then, with greater food availability, obesity was particularly seen in the ruling classes. However, Bray points out that by then, obesity was considered objectionable rather than reflecting a remarkable and unusual status akin to that of a deity. These individuals most likely suffered from not only the common problems of backache and arthritis but also the impact of comorbidities such as diabetes. Chinese and Indian medicine also dealt with obesity as a problem condition, and the particular propensities for Asians and the people of the Middle East to display ill health on weight gain are discussed later. Further on the Roman Galen distinguished between “moderate” and “immoderate” obesity, so in a European rather than an Asian or Middle Eastern context, there may have been a sizable number of overweight individuals with few complications, whereas others were handicapped by their adiposity without this automatically being a reflection of the degree of obesity.
In this ancient literature, it was clear that obesity was considered a clinically unusual event, and so it is little wonder that the original classification of diseases being steadily developed in France during the 19th century included obesity along with other clearly identified clinical abnormalities, some of which were only really apparent on postmortem examination. This classification of diseases was taken over by the World Health Organization (WHO) on its formation in 1948, so in practice, WHO recognized obesity as a disease entity from its inception. However, at this stage, WHO’s primary focus was public health with a heavy emphasis on the poorer countries of the world at a time when obesity was not a problem in lower‐income countries.
Obesity as a public health problem
It is commonly perceived that obesity has only recently been recognized as a public health issue and its potential impact on population health is still yet to be completely acknowledged. However, in his book titled “Fat in the Fifties,” Rasmussen [2] describes a period in post‐World War II America when obesity was being described as the greatest threat to public health. During the 1940s, heart disease replaced infectious diseases as the major cause of death in the United States. At the same time, data from insurance companies identified that higher body weight (relative to height) was associated with an increased risk of premature death, including those from heart disease, and thus obesity was defined as the major public health concern to be addressed. In the 1950s, research by Keys and his colleagues suggested that the three major risk factors for coronary heart disease (CHD) were smoking, high blood pressure, and a high plasma cholesterol level. These findings were seized upon and promoted by vested interests such as the sugar industry that were threatened by the suggestion that excess calories were driving the rise in heart disease and cancer. Although it was recognized that weight gain increased both blood pressure and blood cholesterol levels but obesity per se did not seem to be nearly as important as an independent predictor; in Key’s analysis, the olive oil eating, fatter Greek men had one of the lowest CHD rates. As a consequence, obesity lost its prominence as a key public health issue and was buried by the avalanche of concern around what was then described as the “true” risk factors for heart disease.
Obesity was again raised as a serious public health issue in the early 1970s. One author (W.P.T. James) was involved in producing the UK report on obesity for the UK Department of Health and Social Services and the Medical Research Council [3]. At that stage, obesity was being defined as a percentage excess weight above the desirable weight for height listed by the US Metropolitan Life Insurance Company in complex tables with weights in clothes for three personally chosen frame sizes. These figures relating to pre‐Second World War mortality statistics that were collected on millions of insurance‐eligible Americans. The UK report wanted a standardized measure of body weight that would account for people of different sizes and adopted the approach of the Belgian mathematician Quetelet’s from 1835, who recommended that this could be best achieved deriving the index W/H2 in metric units; a unit now termed the body mass index (BMI). It became apparent that when taking the insurance tables and then considering only the lower limits of the small frame size and the upper limit of the large frame size that the derived Quetelet index was almost the same across a huge range in heights. This ideal body weight from the insurance tables translated into an index of 19.1–24.6 for women and to 19.7–24.9 for men after adjusting for the weight of light clothing and shoe heights. John Garrow, a member of the committee, then rounded these numbers for clinical use to BMI of 20–25. Based on the insurance company’s approach of specifying obesity when weights were 20% above ideal, obesity cut‐off was set at BMI 30.