Jacob C. Seidell

Obesity, insulin resistance and diabetes--a worldwide epidemic.

Obesity is now commonly defined in adults as a BMI > 30 kg/m2. The prevalence of obesity in established market economies (Europe, USA, Canada, Australia, etc.) varies greatly, but a weighed estimate suggests an average prevalence in the order of 15-20%. The prevalence in these countries generally shows increasing trends over time. Obesity is also relatively common in Latin America, but much less so in sub-Saharan Africa and Asia where the majority of the world population lives. Nevertheless obesity rates are increasing there as well and, more importantly, rates of diabetes are increasing even more quickly, particularly in Asian countries. The risks of type 2 diabetes mellitus in these countries tend to increase sharply at levels of BMI generally classified as acceptable in European and North American white people. There have been suggestions to adopt specific classifications of obesity in Asians (e.g. BMI 23 for overweight and 25 or 27 kg/m2 for obesity) and this will greatly affect the prevalence estimates of obesity worldwide (currently at about 250 million people). Particularly for health promotion purposes BMI may be replaced by a classification based on waist circumference, but also specific classifications for different ethnic groups may be necessary. The number of diabetics has been projected to increase from 135 million in 1995 to 300 million in 2025. Much of this increase will be seen in Asia. In summary, both obesity and type 2 diabetes are common consequences of changing lifestyles (increased sedentary lifestyles and increased energy density of diets). Both are potentially preventable through lifestyle modification on a population level, but this requires a coherent and multifaceted strategy. Such strategies are not developed or implemented. These developments point toward the great urgency to develop global and national plans for adequate prevention and management of obesity and type 2 diabetes mellitus.

Visceral fat accumulation in men is positively associated with insulin, glucose, and C-peptide levels, but negatively with testosterone levels

Twenty-three healthy men (age 25 to 50 years), covering a wide range of fatness and body fat distribution, were studied. An oral glucose tolerance test was performed and adipose tissue areas were calculated from computed tomography (CT) scans made at the level of L4/L5. Visceral fat area was associated with elevated concentrations of insulin and C-peptide and with glucose intolerance before and after the oral glucose load. Concentrations of sex-hormone-binding globulin (SHBG), as well as total and free testosterone, were negatively correlated with waist/hip circumference ratio and visceral fat area and also negatively associated with increased glucose, insulin, and C-peptide concentrations. In multiple linear regression, adjusting for age, body mass index, and visceral fat area, serum concentrations of free testosterone were still negatively correlated with glucose, insulin, and C-peptide levels. Without claiming any causality in the observed associations, we conclude that, unlike in women, abdominal fat distribution, insulin, glucose, and C-peptide levels are negatively associated with serum testosterone levels in men.

Impairment of health and quality of life in people with large waist circumference

BACKGROUND Symptoms and secondary disorders associated with excess central fat distribution are being increasingly recognised. We aimed to define the symptoms and assess risks of chronic disorders in people with large waist circumferences. METHODS We did a cross-sectional study of 5887 men and 7018 women aged 20-59 years from the general population of Maastricht, Amsterdam, and Doetinchem, Netherlands. We assessed in health centres respiratory insufficiency, low back pain, degree of physical function, presence of non-insulin-dependent diabetes, and cardiovascular risk factors. We measured bodyweight, body-mass index, and waist circumference by action levels (men: less than action level 1 <94.0 cm, action levels 1-2 94.0-101.9 cm, more than action level 2 > or =102.0 cm; women: less than action level 1 <80.0 cm, action levels 1-2 80.0-87.9 cm) more than action level 2 > or =88.0 cm). The reference group were people with waist circumferences lower than action level 1. FINDINGS All symptoms and risks increased among participants higher than action level 2, after adjustment for age and lifestyle, by 3.1 (95% CI 2.5-3.7) in men and 2.7 (2.3-3.1) in women for shortness of breath when walking upstairs; 4.5 (2.5-7.8) and 3.8 (1.9-7.3) for non-insulin-dependent diabetes; and 4.2 (3.6-5.0) and 2.8 (2.4-3.2) for at least one major cardiovascular risk factor. Above action level 2, compared with the reference group, men and women were at twice the risk of difficulties in everyday activities, women were 1.5 times more likely to have low back pain or symptoms of intervertebral disc herniation, with secondary problems including hindrance to daily activities. INTERPRETATION People with large waist circumferences have excess burden of ill health. Waist action levels could be useful for health promotion to raise awareness of the need for weight management.

Selection of anthropometric indicators for classification of abdominal fatness--a critical review.

In the literature, a variety of anthropometric indicators for abdominal obesity have been suggested. The criteria for their selection vary, and they have been justified mainly on the basis of being correlated with other risk factors, with morbidity and mortality, or to be predictors of the amount of visceral fat. Many of the studies, however, suffer from methodological limitations: they are based on a small number of subjects, often derived from cross-sectional data, based on indirect measurement of risk, or the indicators are complicated to interpret biologically or difficult to use in a public health context. The literature lacks a systematic evaluation of the proposed indicators taking into account possible differences between genders, age categories and ethnic groups and different diseases and mortality.Similar considerations relate to the cut-off points based on the indicators of abdominal obesity. The suggested cut-off points for waist-hip ratio have been based on rather arbitrary criteria, and the studies where cut-off points for waist circumference have been suggested have methodological shortcomings as well, such as being based on cross-sectional data and arbitrary cut-off points for other variables. It is also a reason for concern that so far all suggested cut-off points for abdominal obesity have been based on results obtained in Caucasian populations. Moreover, they are based on assessment of risk and their appropriateness in the use of intervention has not been evaluated. Therefore, no consensus about the appropriateness of the different cut-off points has been reached.We conclude that there is an apparent lack of consistency in the field and therefore a more scientifically and theoretically solid basis for the selection and use of anthropometric indicators of abdominal obesity and cut-off points based on them should be a high priority in this research field in the near future.

Independent and opposite associations of waist and hip circumferences with diabetes, hypertension and dyslipidemia: the AusDiab Study

OBJECTIVE: Fat distribution as measured by waist-to-hip ratio has been shown to be an important independent predictor of glucose intolerance. Few studies, however, have considered the contributions of the waist and hip circumferences independently. The aim of this study was to investigate the independent associations of waist and hip circumference with diabetes in a large population-based study, and to investigate whether they also apply to other major components of the metabolic syndrome (hypertension and dyslipidemia). In addition, as previous studies were performed in older persons, we investigated whether these associations were present across adult age groups.METHODS: Weight, height, waist and hip circumferences were measured in 11 247 participants of the nationally representative Australian Diabetes, Obesity and Lifestyle (AusDiab) Study. HDL-cholesterol, triglycerides, fasting and 2-h postload glucose were determined, and diastolic and systolic blood pressure was measured. After exclusion of persons already known to have diabetes, hypertension or dyslipidemia, logistic and linear regression were used to study cross-sectional associations of anthropometric variables with newly diagnosed diabetes, hypertension and dyslipidemia, and with continuous metabolic measures, all separately for men (n=3818) and women (n=4582). Analyses were repeated in the same population stratified for age.RESULTS: After adjustment for age, body mass index and waist, a larger hip circumference was associated with a lower prevalence of undiagnosed diabetes (odds ratio (OR) per one s.d. increase in hip circumference 0.55 (95% CI 0.41–0.73) in men and 0.42 (0.27–0.65) in women) and undiagnosed dyslipidemia (OR 0.58 (0.50–0.67) in men and 0.37 (0.30–0.45) in women). Associations with undiagnosed hypertension were weaker (OR 0.80 (0.69–0.93) in men and 0.88 (0.70–1.11) in women). As expected, larger waist circumference was associated with higher prevalence of these conditions. Similar associations were found using continuous metabolic variables as outcomes in linear regression analyses. Height partly explained the negative associations with hip circumference. When these analyses were performed stratified for age, associations became weaker or disappeared in the oldest age groups (age ≥75 y in particular), except for HDL-cholesterol.CONCLUSION: We found independent and opposite associations of waist and hip circumference with diabetes, dyslipidemia and less strongly with hypertension in a large population-based survey. These results emphasize that waist and hip circumference are important predictors for the metabolic syndrome and should both be considered in epidemiological studies. The associations were consistent in all age groups, except in age ≥75 y. Further research should be aimed at verifying hypotheses explaining the ‘protective’ effect of larger hips.

Does the relationship between waist circumference, morbidity and mortality depend on measurement protocol for waist circumference?

There is currently no consensus regarding the optimal protocol for measurement of waist circumference (WC), and no scientific rationale is provided for any of the WC protocols recommended by leading health authorities. A panel of experts conducted a systematic review of 120 studies (236 samples) to determine whether measurement protocol influenced the relationship of WC with morbidity of cardiovascular disease (CVD) and diabetes and with mortality from all causes and from CVD. Statistically significant associations with WC were reported for 65% (152) of the samples across all outcomes combined. Common WC protocols performed measurement at the minimal waist (33%), midpoint (26%) and umbilicus (27%). Non‐significant associations were reported for 27% (64) of the samples. Most of these protocols measured WC at the midpoint (36%), umbilicus (28%) or minimal waist (25%). Significant associations were observed for 17 of the remaining 20 samples, but these were not significant when adjustment was made for covariates. For these samples, the most common WC protocols were the midpoint (35%) and umbilicus (30%). Similar patterns of association between the outcomes and all WC protocols were observed across sample size, sex, age, race and ethnicity. Our findings suggest that WC measurement protocol has no substantial influence on the association between WC, all‐cause and CVD mortality, CVD and diabetes.

Prevention Conference VII Obesity, a Worldwide Epidemic Related to Heart Disease and Stroke: Group III: Worldwide Comorbidities of Obesity

Current concerns about the increased risk of cardiovascular and other diseases induced by excessive weight gain in children and adults have been highlighted by the Surgeon General’s report on the problem of obesity in the United States.1 This call to action followed a global analysis of the problem of excess weight and how to define and combat it that was undertaken by the World Health Organization (WHO) in 19972 and an analogous National Institutes of Health (NIH) assessment and reclassification of US rates of overweight and obesity in 1998.3 It is generally accepted that body mass index (BMI), or weight in kilograms per square meter of height, is a convenient measure of an approximate height-independent index of both children and adults’ weight for height and provides a crude indication of the body’s fat content. It is becoming clear that different ethnic groups have different proportions of fat-to-lean tissues at equivalent BMIs4,5 and that the magnitude of the multiple comorbidities associated with higher BMIs also may differ among different ethnic groups for reasons that may reflect the impact of environmental–genetic interactions. Nevertheless, current international comparisons use a standard format and classification system. In all societies a spectrum of BMIs exists for children and adults of all ages. Individual positions within the percentile range tend to remain the same as children grow and adults steadily gain weight. As the average weight of children and adults increases, so does the spread of BMIs, with a marked progressive increase in the numbers with very high BMIs (see Figure 1). Thus, the escalation in obesity rates reflects the upward shift in body weights of the whole population in response to environmental changes. Adults with a BMI of 18.5 to 24.9 are categorized as being of normal weight, on the basis of …

Effects of sex steroids on components of the insulin resistance syndrome in transsexual subjects

objective Sex differences are found in most components of the insulin resistance syndrome and the associated cardiovascular risk profile. These differences are attributed to sex‐specific sex steroid profiles, but the effects of sex steroids on the individual components of the insulin resistance syndrome remain incompletely understood.

Waist and hip circumferences, and waist-hip ratio in 19 populations of the WHO MONICA Project

OBJECTIVE: To assess differences in waist and hip circumferences and waist-to-hip ratio (WHR) measured using a standard protocol among populations with different prevalences of overweight. In addition, to quantify the associations of these anthropometric measures with age and degree of overweight.DESIGN: Cross-sectional study of random population samples.SUBJECTS: More than 32 000 men and women aged 25–64 y from 19 (18 in women) populations participating in the second MONItoring trends and determinants in CArdiovascular disease (MONICA) survey from 1987–1992.RESULTS: Age standardized mean waist circumference range between populations from 83–98 cm in men and from 78–91 cm in women. Mean hip circumference ranged from 94–105 cm and from 97–108 cm in men and women, respectively, and mean WHR from 0.87–0.99 and from 0.76–0.84, respectively. Together, height, body mass index (BMI), age group and population explained about 80% of the variance in waist circumference. BMI was the predominant determinant (77% in men, 75% women). Similar results were obtained for hip circumference. However, height, BMI, age group and population, accounted only for 49% (men) and 30% (women) the variation in WHR.CONCLUSION: Considerable variation in waist and hip circumferences and WHR were observed among the study populations. Waist circumference and WHR, both of which are used as indicators of abdominal obesity, seem to measure different aspects of the human body: waist circumference reflects mainly the degree of overweight whereas WHR does not.

Prevalence of overweight and obesity in the Netherlands.

This paper shows the trends in the prevalence of overweight (body mass index [BMI] ≥ 25 kg m−2) and obesity (BMI ≥ 30 kg m−2) in the Netherlands. Overweight (obesity) prevalence in adult males increased from 37% (4%) in 1981 to 51% (10%) in 2004, and in adult females from 30% (6%) in 1981 to 42% (12%) in 2004, according to self‐reported data. In boys and girls, obesity prevalence doubled or even tripled from 1980 to 1997, and again from 1997 to 2002–2004 a two‐ or threefold increase was seen for almost all ages. According to the most recent data, overweight (obesity) prevalence figures range, depending on age, from 9.2% to 17.3% (2.5–4.3%) in boys, and from 14.6% to 24.6% (2.3–6.5%) in girls. There is a lack of data on the national prevalence of overweight and obesity based on measured height and weight and on prevalences in different subgroups of the population. Regular national representative health examination surveys that measure height and weight are needed to assess the prevalence of overweight and obesity and its distribution over subgroups in the population, and to properly direct and evaluate prevention activities.