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Obesity is probably one of the most misunderstoodconditions of ill-health, with surprising ignoranceamongst even highly qualified specialists in the med-ical profession. It is often considered mainly as acondition inflicted by patients themselves, avoidablewith a minimum of self-control and discipline.Recent research and measurements have revealed atotally different picture. Human energy balance isregulated by strong genetic determinants, althoughthe precise gene(s) are not yet known.

The heritability is stronger than for hypertension,schizophrenia and alcoholism. Obesity genes wereconstructed for an opportunistic purpose, to collectenergy when periodically available. This clearly had asurvival value. Today, when we in the Western indus-trialized world are surrounded by an easily availableexcess of food, the regulatory system is exposed tooverloading and easily overrided. This is particularlythe case since energy output is minimized by con-struction and availability of various energy-savingdevices utilized daily. The regulatory system of energyintake is thus working on such a low level that evenminor overshoots of energy intake are, in the longterm, resulting in obesity. To take an example, anextra sandwich per day has the consequense of about8 kg weight increase per year. This is such a smallchange of eating habits that it is probably not notice-able by even an observant person, and barelydetectable by sophisticated, modern methods to mea-sure energy balance.

In summary, we are facing the following problem.On the basis of a strong genetic background, actuallyconstructed for opposite purposes than avoiding fatstorage, there is thus a minute, in practice non-

observable, excess of energy intake. This is clearly ahuge problem to cope with in disease prevention.

A serious question is whether we will be able todeal with this problem with some hope of success inpreventive efforts. Another question is: does it matter?The clear answer is that it is necessary to start seriousinterventions because obesity is not only a precursorstate to prevalent disease, but also one of the mostexpensive factors of health costs.

A group of obesity scientists was assembled on theinitiative of professor Phillip James, Aberdeen, to startto thoroughly examine the problem and to initiateinternational counteractions. Some 15 obesityexperts from different parts of the world formed anInternational Obesity Task Force (IOTF). This grouptook it upon themselves to scrutinize the problemworldwide, and eventually report the results to theWorld Heatlh Organization (WHO). WHO, in turn,realized the magnitude and seriousness of the prob-lem, and decided to be involved in future counterac-tions, based on the IOTF report. This report,minimally revised during a WHO discussion in June1997, is now available [1]. The following summarydescribes its highlights.

Definitions

Body mass index (BMI, weight/height2; kg/m2) wasutilized for setting the borderlines. Obesity wasdefined as a BMI . 30, which means that at heightsof 180, 170 and 160 cm, weights above of about100, 90 and 80 kg are the limit for a diagnosis ofobesity for both men and women. This obviously pro-vides a clear and acceptable diagnosis.

EDITORIAL

Obesity: a chronic disease with alarming prevalence andconsequences

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Epidemiology

Utilizing these limits, data from Monica studies, orobservations of comparable reliability, were used tomap out the international situation [1]. In Europe,the Scandinavian figures are lowest, being about10% in middle-aged subjects in Sweden, Norway andDenmark, whilst Finland shows twice this preva-lence. The figures on the western part of the conti-nent, including England, are about 15–20%. In theeast, a much worse prevalence was observed,approaching 70% amongst women in Lithuania andRussia. In the US the prevalance is close to 30%, withdramatic peaks in minorities such as blacks, andsome American Indian tribes. In Australian aborig-inies and the population on certain Pacific inlands,the prevalance approaches 100%.

There are clear indications of rising prevalence inseveral countries, including Sweden. In addition, indeveloping countries such as in the Carribean area,South America and South-East Asia, obesity is nowalso becoming more common. In China theprevalance is low, but also rising. In absolute num-bers a 1% increase in China corresponds to manymillions of obese subjects, in a population whichseems particularly vulnerable to diabetes (type 2) [1].

The global situation is thus alarming, and counter-measures are indicated. Treatment can only beoffered to those with severe comorbidities due to themagnitude of the problem. Prevention must be thestrategy selected. The WHO, with the assistance of anumber of professional and lay organizations, willadvise and lead such efforts.

Consequences

Why is this necessary? Obesity it the most prevalentprecursor to diabetes type 2. In the Western world ithas been estimated that about one-third of obesesubjects develop diabetes. In other parts of the worldthis fraction is much higher, approaching 100% in,for example, American Indians and Pacific islanders.Although some decades ago there was a fierce discus-sion about whether obesity is a risk factor for cardio-vascular disease or not, it is now clear that this isindeed the case. The key observation here was thediscovery of different risks in subgroups of obesitywhere abdominal obesity is a risk factor of the samepower as, for example, hypertension and dyslipi-daemia [2].

Several other conditions are associated with obesi-ty, including certain types of malignancy. The psy-chosocial suffering and locomotor problems shouldnot be forgotten and are particularly prevalent [1].

It seems clear that obesity with its associated mor-bidities is currently one of the most severe healthproblems. The total health costs attributable to obesi-ty, including direct and indirect economic expendi-ture such as costs of the fractions of diabetes etc.,have been estimated to about 7–8% of total healthcosts in Sweden [3]. This is thus a heavy burden onthe country’s health budget, and any improvement ofthe situation would make large savings possible.

It is of some interest to compare today’s situationwith that of, say, 100 years ago, where tuberculosiswas the most prevalent plague. This was frequentlybased on undernutrition. Now we are facing anotherlarge problem due mainly to overnutrition.

Pathogenesis

What is the explanation of this development? Obesityis due to a positive energy balance, explained byeither increased energy intake or a too low energyoutput, or both. Observations suggest that it is partic-ularly the diminishing energy expenditure in modernsociety which is responsible [1]. This is no surprisewith all the constructions available to avoid muscu-lar work during both work and leisure time.

In a way this might be fortunate because it may beeasier, or rather less difficult, to increase physicalactivity than to change food habits in the population.One should keep in mind that in the long term onlyminor changes are necessary, such as a 15–30 minwalk daily, using stairs instead of escalators, etc. Thiscould be attainable perhaps by closing city centresfrom car traffic, stopping escalators, etc. Facilities forphysical activity should be provided, e.g. by makingpavements and cycling lanes more available andsafer.

Conclusion

There is now a clear need to actively counteract theproblem of obesity worldwide due to the suffering,morbidity and economic costs of this condition.WHO will take the lead in this difficult, but necessaryprocess. National efforts are also necessary and maydiffer due to expected domestic differences in coun-termeasures. Such initiatives have already been

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taken in several countries, e.g. the UK and the USA.In Sweden, the Swedish Council of TechnologyAssessments in Health Care (SBU) has recently takenthe initiative to describe the Swedish situation and torecommend counteractivities.

P E R B J Ö R N T O R P

Department of Heart and Lung Diseases, University of Göteborg, Sweden

References1 World Health Organization. Obesity. Preventing and manag-

ing the global epidemic. WHO/NUT/98.1. Geneva: WHO,1998.

2 Björntorp P. Visceral obesity: a civilization syndrome. Obes Res1993; 1: 206–22.

3 Sjöström L, Narbro K, Sjöström D. Costs and benefits whentreating obesity. Int J Obesity 1995; 19 (Suppl. 6): S9–12.

Received 13 May 1998; accepted 9 June 1998.

Correspondence: Professor Per Björntorp, Department of Heart andLung Diseases, University of Göteborg, Sweden (fax: 146 031826540).