A break in the obesity epidemic? Explained by biases or misinterpretation of the data?

Recent epidemiologic papers are presenting prevalence data suggesting breaks and decreases in obesity rates. However, before concluding that the obesity epidemic is not increasing anymore, the validity of the presented data should be discussed more thoroughly. We had a closer look into the literature presented in recent reviews to address the major potential biases and distortions, and to develop insights about how to interpret the presented suggestions for a potential break in the obesity epidemic. Decreasing participation rates, the use of reported rather than measured data and small sample sizes, or lack of representativeness, did not seem to explain presented breaks in the obesity epidemic. Further, available evidence does not suggest that stabilization of obesity rates is seen in higher socioeconomic groups only, or that urbanization could explain a potential break in the obesity epidemic. However, follow-ups of short duration may, in part, explain the apparent break or decrease in the obesity epidemic. On the other hand, a single focus on body mass index (BMI) ⩾25 or ⩾30 kg m(-)(2) is likely to mask a real increase in the obesity epidemic. And, in both children and adults, trends in waist circumferences were generally suggesting an increase, and were stronger than those reported for trends in BMI. Studies concluding that there is a recent break in the obesity epidemic need to be interpreted with caution. Reported studies presenting a break were mostly of short duration. Further, focusing on trends in waist circumference rather than BMI leads to a less optimistic conclusion: the public health problem of obesity is still increasing.

Changes in body mass index and measures of abdominal obesity in Finnish adults between 1992 and 2007, the National FINRISK Study.

UNLABELLED: What is already known about this subject • Recent obesity trends across the world in adults are mixed, varying from showing signs of levelling off to a continuously increasing prevalence. • Secular trends in body mass index (BMI) and waist circumference may vary by sex and age. • Relying exclusively on BMI data may lead to underestimate the obesity epidemic. What this study adds • Adverse trends in obesity indicators have continued in Finland in the 2000s. • In older men, BMI remained quite stable and in older women BMI has decreased since 1997. • Steep upward trends in abdominal obesity (waist circumference and waist-to-height ratio, WHtR) have taken place in both men and women and in all age groups, especially during the past 10 years. • The impact of BMI adjustment on trends in abdominal obesity varied by age such that increases in BMI-adjusted waist circumference and WHtR were more prominent in older age groups. SUMMARY: Signs that obesity trends will level off at the turn of the 21st century have been reported. In these studies, however, the definition of obesity has been based only on body mass index (BMI). We investigated obesity trends among Finnish adults over recent years by using BMI, waist circumference and waist-to-height ratio as indicators for obesity. Data were derived from the national FINRISK surveys, which are cross-sectional population surveys conducted at 5-year intervals between 1992 and 2007. Altogether, 20 551 randomly selected men and women aged 25-64 years participated in health examinations, where weight, height, and waist and hip circumferences were measured by trained nurses. Mean BMI increased in younger men and women (aged 25-44 years) between 1992 and 2007, whereas in older men, BMI remained quite stable and in older women BMI has decreased since 1997. Nevertheless, mean waist circumference and waist-to-height ratio increased in both men and women over the 15-year period. The upward trends took place in all age groups, especially during the past 10 years. Adverse trends in obesity indicators have continued in Finland in the 2000s. In particular, concerns are related to steep upward trends in abdominal obesity.

Health behaviors, waist circumference and waist-to-height ratio in children.

BACKGROUND: Waist circumference (WC) and waist-to-height ratio (WHtR) begin to gain attention as measures of adiposity and as important cardiometabolic disease risk factors also among children. Still, little research has been done on behavioral determinants of WC and WHtR in children. The purpose of this study was to examine associations between health behaviors, WC and WHtR in children. METHODS: The study was a cross-sectional study conducted in Swedish-speaking schools in Helsinki region in 2006. In all, 1146 children were recruited, from which 55 % took part in the study. A total of 604 9-11-year-old children (312 girls, 292 boys) were measured by research staff and completed a study questionnaire on their health behaviors, including breakfast intake, TV viewing, sleep duration and physical activity, and a 16-item food frequency questionnaire. Covariance analysis was used as the statistical analysis method. RESULTS: When controlling for other health behaviors, for example, irregular breakfast (B-coefficient 2.49 CI, 0.64-4.34; P<0.01), TV viewing (B-coefficient 0.89 CI, 0.17-1.61; P<0.05), a TV in child's room (B-coefficient 2.30 CI, 0.73-3.86; P<0.01) and physical inactivity during school breaks (B-coefficient 0.78 CI, 0.19-1.37; P<0.01) were associated with larger WC. Results were similar with WHtR. CONCLUSIONS: Many health behaviors were related to children's WC and WHtR. Determinants were associated to both WC and WHtR similarly.

Twenty-year changes in the prevalence of obesity among Finnish adults.

We investigated changes in the prevalence of obesity among Finnish adults (aged > or = 30 years) during a 20-year period. Data were derived from two cross-sectional nationally representative surveys (n = 13 844) in 1978-1980 and 2000-2001. Weight and height were measured using a standardized protocol. Obesity was defined as body mass index (BMI) > or = 30 kg m(-2). Cut-offs of BMI > or = 35 kg m(-2) and BMI > or = 40 kg m(-2) were also used. A 20-year difference in the prevalence of obesity was from 11.3% to 20.7% in men and from 17.9% to 24.1% in women. In 1978-1980, 1.1% of men and 3.8% of women had a BMI at least 35 kg m(-2). The corresponding prevalence was 3.9% in men and 6.8% in women 20 years later. The educational gradient in obesity diminished in 20 years because of the most prominent increase among highly educated men. Yet, 25% of men and 28% of women with low education are obese. Obesity increased in all age and educational groups over the 20-year period. It was highest among women and individuals with the lowest education, but the increase was most striking among well-educated men. A comprehensive public health strategy targeting the whole population and especially those with low education is urgently needed to halt the obesity epidemic.

Socio-economic status and abdominal obesity among Finnish adults from 1992 to 2002.

OBJECTIVE: To examine 10-year changes in waist circumference (WC) and identify socio-economic groups having higher WC than expected by their body mass index (BMI). DESIGN: Population based cross-sectional surveys carried out in four regions of Finland in 1992, 1997 and 2002. SUBJECTS: A total of 9026 women and 8173 men, aged 25-64 years. MEASUREMENTS: Waist circumference, BMI, socio-economic indicators (education, household income, employment status, marital status) and health behaviors (smoking, alcohol use, physical activity). RESULTS: In 2002, women had about 2.7 cm and men about 1.0 cm higher WC than subjects 10 years previously. Waist circumference increased more than BMI among women, especially among unemployed women. Higher WC among non-employed women was not explained by socio-economic indicators or health behaviors. Among men, smaller WC was associated with lower socio-economic status. However, associations partly disappeared after adjustment for health behaviors including physical activity at work. CONCLUSION: Socio-economic patterning of WC is divergent and gender-specific. More attention should be paid to increasing waistlines among women.

Nutrition and cardiovascular disease in Finland since the early 1970s: a success story.

This paper describes the Finnish experience on the population strategy to prevent cardiovascular disease with special reference to diet. Systematic work to lower the risk factors of cardiovascular disease started in the early 1970s with the North Karelia project and rapidly expanded to cover the whole country. The main aims were to change the type of fats used, to lower sodium intake and to increase vegetable and fruit consumption. Concurrently, a comprehensive monitoring system was developed including regular population surveys every five years. During the period 1972-1997 major changes took place in the diet as well as in blood pressure and serum cholesterol levels. At the same time, cardiovascular mortality decreased dramatically. The Finnish experience shows that dietary changes are possible but require a persistent and comprehensive intervention.

Secular trends in body mass index by birth cohort in eastern Finland from 1972 to 1997.

OBJECTIVE: To describe changes in body mass index (BMI) with age over a 25 y period, and to investigate whether those changes differed by birth cohort, gender or education. DESIGN: Six cross-sectional population surveys repeated in eastern Finland every fifth year between 1972 and 1997. Synthetic birth cohorts were created by dividing subjects into twelve 5 y groups according to birth year. SUBJECTS: Independent random samples from the national population register including men and women aged 25-64 y, the final sample comprising 18 439 men and 19 501 women. The oldest birth cohort included subjects born in 1913-1917 and the youngest were born in 1968-1972. MEASUREMENTS: Weight and height were measured, and data on educational level were collected by a self-administered questionnaire. RESULTS: A BMI increase with age was more prominent in women (4.2 kg/m(2) in 25 y) than in men (3.3 kg/m(2) in 25 y), and was very similar in all birth cohorts. In men, the BMI increase with age varied across cohorts. Among birth cohorts participating in each survey, the BMI increase over the 25 y period was most prominent (3.9 kg/m(2) in 25 y) in men born between 1943 and 1947. Among all birth cohorts, the strongest upward trend (0.2 kg/m(2) per year) was observed in men born between 1953 and 1957. CONCLUSIONS: Weight gain with age has remained unchanged in women over the 25 y period, whereas in men, the younger the birth cohort, the more prominent was the BMI increase with age.

Trends in waist-to-hip ratio and its determinants in adults in Finland from 1987 to 1997.

BACKGROUND: Although abdominal obesity has been shown to be an important risk factor for cardiovascular disease and a variety of other diseases, secular changes in fat distribution in populations have rarely been documented. OBJECTIVE: Our objective was to assess trends in waist-to-hip ratio (WHR) in the Finnish population during a 10-y period. In addition, we investigated the associations of WHR with body mass index (BMI), age, education, and lifestyle factors. DESIGN: Three independent cross-sectional surveys were carried out at 5-y intervals between 1987 and 1997. Altogether, 15096 randomly selected men and women aged 25-64 y participated in these surveys. RESULTS: The WHR increased in both men and women during the 10-y period (P: < 0.0001). In men, the strongest upward trend took place in the first 5-y period and then seemed to plateau; in women, the WHR continued to increase into the 1990s. In both sexes, the most prominent increase was observed in subjects aged >/=45 y. The WHR increased in all education-level groups, the lowest WHR being among those with the highest education. Age (18% in men, 12% in women) and BMI (33% in men, 25% in women) accounted for most of the variation in WHR, whereas only 3% was explained by education and lifestyle factors. CONCLUSIONS: Abdominal obesity is a growing problem in Finland, especially in persons aged >/=45 y. These adverse changes in body shape continued to take place, particularly in women, in the 1990s.

Age, education and occupation as determinants of trends in body mass index in Finland from 1982 to 1997.

OBJECTIVE: To investigate trends in body mass index (BMI) and prevalence of obesity among adults in Finland from 1982 to 1997, and to identify population groups with increasing obesity. SUBJECTS: Random samples from the national population register including men and women aged 25-64 y (n = 24604, total). DESIGN: Four cross-sectional surveys carried out in three areas in Finland every fifth year since 1982. MEASUREMENTS: Weight and height were measured, and data on occupation and education level were collected by a self-administered questionnaire. RESULTS: The mean BMI increased in both genders. In men, the upward trend was greatest (the increase of 1.3 kg/m2 in 15 y) in the oldest age group (55-64 y), and was found also (the increase of 0.6 kg/m2) in the youngest age group (25-34 y), whereas in women, the upward trend was most prominent (the increase of 0.9 kg/m2) in the youngest age group. BMI increased in all educational groups in men, but in women the upward trend seemed to be greatest in the lowest educational group. The upward trends were most prominent among retired and unemployed men, while in women changes in BMI were similar in all occupational groups. CONCLUSION: The strongest upward trend in BMI was found in the oldest men, in the youngest age group in both genders and, in particular, among men who were outside the labor force. Education is still a strong determinant of obesity, especially in women, although the social gradient in BMI has not widened in the 1990s.

The validity of a food use questionnaire in assessing the nutrient intake of physically active young men.

The validity of a self-administered food use questionnaire, comprising 122 questions on food items or dishes and designed especially to assess the intake of micronutrients, was evaluated using a 7-day food record (7DR) as a reference method. The subjects kept the food record after they filled in the questionnaire. Eighty-four male athletes participated in this study. The nutrient intake from the food use questionnaires was calculated in two ways: (i) in questionnaire 1 (FUQ-1), the portion size reported by the subjects was used, and (ii) in questionnaire 2 (FUQ-2), a 'typical' portion size was used regardless of the subject's report. In FUQ-1, the reported nutrient intake tended to be overestimated in comparison to the 7DR, whereas in FUQ-2 comparable results on a group level for all nutrients, except for proteins and fats, were obtained. The percentage of subjects similarly classified into tertiles (7DR vs. FUQ-1 or FUQ-2) varied between 37 and 54 per cent. The results show that the food use questionnaire agreed well with the food record on a group level, if a typical portion size was used. However, the agreement on an individual level was not quite as good.