Obesity: a chronic disease with alarming prevalence and consequences

Obesity is probably one of the most misunderstood conditions of ill-health, with surprising ignorance amongst even highly qualified specialists in the medical profession. It is often considered mainly as a condition inflicted by patients themselves, avoidable with a minimum of self-control and discipline. Recent research and measurements have revealed a totally different picture. Human energy balance is regulated by strong genetic determinants, although the precise gene(s) are not yet known. The heritability is stronger than for hypertension, schizophrenia and alcoholism. Obesity genes were constructed for an opportunistic purpose, to collect energy when periodically available. This clearly had a survival value. Today, when we in the Western industrialized world are surrounded by an easily available excess of food, the regulatory system is exposed to overloading and easily overrided. This is particularly the case since energy output is minimized by construction and availability of various energy-saving devices utilized daily. The regulatory system of energy intake is thus working on such a low level that even minor overshoots of energy intake are, in the long term, resulting in obesity. To take an example, an extra sandwich per day has the consequense of about 8 kg weight increase per year. This is such a small change of eating habits that it is probably not noticeable by even an observant person, and barely detectable by sophisticated, modern methods to measure energy balance. In summary, we are facing the following problem. On the basis of a strong genetic background, actually constructed for opposite purposes than avoiding fat storage, there is thus a minute, in practice non-observable, excess of energy intake. This is clearly a huge problem to cope with in disease prevention. A serious question is whether we will be able to deal with this problem with some hope of success in preventive efforts. Another question is: does it matter? The clear answer is that it is necessary to start serious interventions because obesity is not only a precursor state to prevalent disease, but also one of the most expensive factors of health costs. A group of obesity scientists was assembled on the initiative of professor Phillip James, Aberdeen, to start to thoroughly examine the problem and to initiate international counteractions. Some 15 obesity experts from different parts of the world formed an International Obesity Task Force (IOTF). This group took it upon themselves to scrutinize the problem worldwide, and eventually report the results to the World Heatlh Organization (WHO). WHO, in turn, realized the magnitude and seriousness of the problem, and decided to be involved in future counteractions, based on the IOTF report. This report, minimally revised during a WHO discussion in June 1997, is now available [1]. The following summary describes its highlights. Body mass index (BMI, weight/height2; kg/m2) was utilized for setting the borderlines. Obesity was defined as a BMI > 30, which means that at heights of 180, 170 and 160 cm, weights above of about 100, 90 and 80 kg are the limit for a diagnosis of obesity for both men and women. This obviously provides a clear and acceptable diagnosis. Utilizing these limits, data from Monica studies, or observations of comparable reliability, were used to map out the international situation [1]. In Europe, the Scandinavian figures are lowest, being about 10% in middle-aged subjects in Sweden, Norway and Denmark, whilst Finland shows twice this prevalence. The figures on the western part of the continent, including England, are about 15–20%. In the east, a much worse prevalence was observed, approaching 70% amongst women in Lithuania and Russia. In the US the prevalance is close to 30%, with dramatic peaks in minorities such as blacks, and some American Indian tribes. In Australian aboriginies and the population on certain Pacific inlands, the prevalance approaches 100%. There are clear indications of rising prevalence in several countries, including Sweden. In addition, in developing countries such as in the Carribean area, South America and South-East Asia, obesity is now also becoming more common. In China the prevalance is low, but also rising. In absolute numbers a 1% increase in China corresponds to many millions of obese subjects, in a population which seems particularly vulnerable to diabetes (type 2) [1]. The global situation is thus alarming, and countermeasures are indicated. Treatment can only be offered to those with severe comorbidities due to the magnitude of the problem. Prevention must be the strategy selected. The WHO, with the assistance of a number of professional and lay organizations, will advise and lead such efforts. Why is this necessary? Obesity it the most prevalent precursor to diabetes type 2. In the Western world it has been estimated that about one-third of obese subjects develop diabetes. In other parts of the world this fraction is much higher, approaching 100% in, for example, American Indians and Pacific islanders. Although some decades ago there was a fierce discussion about whether obesity is a risk factor for cardiovascular disease or not, it is now clear that this is indeed the case. The key observation here was the discovery of different risks in subgroups of obesity where abdominal obesity is a risk factor of the same power as, for example, hypertension and dyslipidaemia [2]. Several other conditions are associated with obesity, including certain types of malignancy. The psychosocial suffering and locomotor problems should not be forgotten and are particularly prevalent [1]. It seems clear that obesity with its associated morbidities is currently one of the most severe health problems. The total health costs attributable to obesity, including direct and indirect economic expenditure such as costs of the fractions of diabetes etc., have been estimated to about 7–8% of total health costs in Sweden [3]. This is thus a heavy burden on the country's health budget, and any improvement of the situation would make large savings possible. It is of some interest to compare today's situation with that of, say, 100 years ago, where tuberculosis was the most prevalent plague. This was frequently based on undernutrition. Now we are facing another large problem due mainly to overnutrition. What is the explanation of this development? Obesity is due to a positive energy balance, explained by either increased energy intake or a too low energy output, or both. Observations suggest that it is particularly the diminishing energy expenditure in modern society which is responsible [1]. This is no surprise with all the constructions available to avoid muscular work during both work and leisure time. In a way this might be fortunate because it may be easier, or rather less difficult, to increase physical activity than to change food habits in the population. One should keep in mind that in the long term only minor changes are necessary, such as a 15–30 min walk daily, using stairs instead of escalators, etc. This could be attainable perhaps by closing city centres from car traffic, stopping escalators, etc. Facilities for physical activity should be provided, e.g. by making pavements and cycling lanes more available and safer. There is now a clear need to actively counteract the problem of obesity worldwide due to the suffering, morbidity and economic costs of this condition. WHO will take the lead in this difficult, but necessary process. National efforts are also necessary and may differ due to expected domestic differences in countermeasures. Such initiatives have already been taken in several countries, e.g. the UK and the USA. In Sweden, the Swedish Council of Technology Assessments in Health Care (SBU) has recently taken the initiative to describe the Swedish situation and to recommend counteractivities.