The Finnish Programme for the Prevention of Type 2 Diabetes  is the first large-scale national programme ever launched to combat the diabetes epidemic at the population-level. The implementation project of this program, FIN-D2D, focused mainly on the high-risk strategy, and the strategy of early diagnosis and treatment . The FIN-D2D also supported the population strategy and it gained a lot of publicity in the whole country because its main aim was to restrain the obesity epidemic by means of nutritional interventions and increased physical activity. As shown in the present study, this goal was achieved, since the mean body weight, mean BMI, and the prevalence of obesity decreased, whereas the prevalence of normal weight increased. This suggests that the prevalence of obesity may be decreasing among 45-74 year old Finns. To our knowledge, this is the first report to show a decline in the prevalence of obesity at the population-level, both in the FIN-D2D and the control area. Interestingly, the waist circumference increased in the control area, whereas it remained unchanged in the FIN-D2D area. However, the increase in waist circumference in the control area was more modest than reported earlier for years 1987-2002 , and the prevalence of central obesity did not increase significantly in either area.
There is large geographic variation in the prevalence of obesity among European countries, with central, eastern, and southern regions showing higher rates than the western and northern (including Finland) regions . Studies from Spain, Canada, Denmark, Portugal, and South Australia [34–38] have shown that the prevalence of obesity has increased between the mid-1990s and the beginning of the 2000s. In Finland, national FINRISK studies have shown that the increase in BMI has slowed down in men, and has been quite stable in women between 1997 and 2002, whereas a remarkable shift towards higher waist circumference has been observed . BMI did not increase significantly between 1997 and 2002 in the age groups of 35-64 years, but it increased significantly in the youngest age group, 25-34 years, where also the increase in waist circumference was greatest . Among US adults the increases in the prevalence of obesity previously observed does not appear to be continuing at the same rate during the past 10 years, particularly for women . In Sweden, the increase in the prevalence of obesity has levelled off during 2000-2005  compared to the 10% increase seen during the years 1996-2001 . In our study, a significant decrease in the prevalence of obesity at the population-level was seen for the first time.
In addition to the changes seen in the FIN-D2D area, most changes in body weight and the prevalence of obesity were similar in the control area, especially among men. Although the five hospital districts of FIN-D2D formed a pilot area, the information of the importance of healthy lifestyles in the prevention of diabetes had also spread outside the FIN-D2D area, which was the aim of population strategy, as well. Moreover, the control area is part of the FINRISK area, where the measurements of cardiovascular risk factors have been repeated every five years since 1972 with impressing results [27, 28], and they have also received feedback of these results. Therefore, the control area can be considered better as a mini-intervention area rather than a pure control area. The latest FINRISK-survey showed that many cardiovascular risk factors were proceeding into the right direction among 25-64 year old individuals in Finland [4, 41]. However, the use of alcohol was still high , and this could be a reason why the waist circumference was increasing , and why the beneficial trend in blood pressure had now levelled off .
There were also substantial differences among the studied areas on how they succeeded in the project, which can largely be explained by their different ways of action in the prevention of chronic diseases, and also their different population structures. It should also be noted that the prevalence of diabetes in the FIN-D2D area has already for a long time been higher than the mean prevalence of diabetes in Finland . The areas were thus establishing this project from different starting points, but they also reached the goals differently. The FIN-D2D was a national health promoting programme, and not an actual scientific study. However, from the very beginning it was decided to analyse its influence by comparing changes in adiposity markers in the FIN-D2D area and the preselected control area.
In this study based on the two cross-sectional surveys with 3 to 5 years of follow-up it was surprising that men in the FIN-D2D area (especially the youngest age group) were able to reduce their body weight more than women. Usually women are more likely to participate in lifestyle change programmes than men . In FIN-D2D there were several projects focusing on men especially, which may have encouraged men to join these projects, and to also succeed in them. The threshold for men to participate is usually higher than that for women, but their commitment nevertheless is usually better [43–45]. Also, the interventions aimed at women may indirectly affect also men due to the fact that men usually eat meals prepared by women . Women in the control area showed beneficial changes in the prevalence of normal weight and overweight, but on the other hand, adverse changes regarding waist circumference and the prevalence of morbid obesity. Of course, one could speculate, whether the result concerning morbid obesity is a real finding or just a statistical coincidence. However, both FIN-D2D and the control population are selected as random independent samples of individuals, specified by region, gender, and age group, being thus a representative sample of the population. Similar changes in the prevalence of morbid obesity were observed in all sub-regions, i.e. the prevalence of morbid obesity increased in all sub-regions of the control area, and remained unchanged, in all FIN-D2D hospital districts.
The prevalence of severe (BMI ≥35 kg/m2) and morbid (BMI ≥40 kg/m2) obesity has increased in Finland 2.7-fold and 5.6-fold, respectively, during 1978-2001 . Although the number of massively obese individuals is still rather low in Finland, it would be of importance to restrain their number from increasing further. In USA the prevalence of morbid obesity is 5.4% in the age group of 40 or older , which is nearly three times the prevalence in Finland (1.9% with FIN-D2D and FINRISK studies combined). Although rather rare, this extreme group of people incur huge expenses along with increasing surgical treatment of obesity.
The present results indicate that the obesity epidemic might be stabilizing or even decreasing in Finland. If this trend is sustainable, also the incidence of type 2 diabetes might follow the obesity trends, and ease off during the years to come. To achieve this goal, we must now be able to maintain and to continue the progression already made regarding body weight. Furthermore, it would also be very important to be able to spread healthier lifestyles into the younger age groups, since obesity appears to reduce life expectancy markedly, especially among younger adults .