Criteria for definition of overweight in transition: background and recommendations for the United States

Overweight and obesity are leading nutrition-related disorders of clinical and public health concern. Assessment and classification of these conditions are dependent on specific body mass index (BMI; in kg/m(2)) cutoff points. US government agencies are making the transition to a revised BMI definition of overweight from that previously recommended for general use. The purpose of this article is to inform the broader medical and scientific communities of the transition that is underway in the United States to identify and classify overweight among adults by using BMI. Historical background on the use of BMI in a variety of applications, as reported in US federal government agency documents, provides an understanding of previous and current weight-for-height guidelines and the basis for arriving at them. On the basis of the current Dietary Guidelines for Americans, US government agencies are moving toward the use of criteria for overweight and obesity that are consistent with current international standards. Clinicians, researchers, and journal editors should be aware of the transition toward a common definition of healthy weight, overweight, and obesity. To facilitate comparisons and reporting of data, others are encouraged to consider making this transition as well.

Adolphe Quetelet (1796 1874) the average man and indices of obesity

The quest for a practical index of relative body weight that began shortly after actuaries reported the increased mortality of their overweight policyholders culminated after World War II, when the relationship between weight and cardiovascular disease became the subject of epidemiological studies. It became evident then that the best index was the ratio of the weight in kilograms divided by the square of the height in meters, or the Quetelet Index described in 1832. Adolphe Quetelet (1796-1874) was a Belgian mathematician, astronomer and statistician, who developed a passionate interest in probability calculus that he applied to study human physical characteristics and social aptitudes. His pioneering cross-sectional studies of human growth led him to conclude that other than the spurts of growth after birth and during puberty, 'the weight increases as the square of the height', known as the Quetelet Index until it was termed the Body Mass Index in 1972 by Ancel Keys (1904-2004). For his application of comparative statistics to social conditions and moral issues, Quetelet is considered a founder of the social sciences. His principal work, 'A Treatise of Man and the development of his faculties' published in 1835 is considered 'one of the greatest books of the 19th century'. A tireless promoter of statistical data collection based on standard methods and definitions, Quetelet organized in 1853 the first International Statistical Congress, which launched the development of 'a uniform nomenclature of the causes of death applicable to all countries', progenitor of the current International Classification of Diseases.

The Harris-Benedict studies of human basal metabolism: history and limitations

In the early part of the 20th century, numerous studies of human basal metabolism were conducted at the Nutrition Laboratory of the Carnegie Institution of Washington in Boston, Mass, under the direction of Francis G. Benedict. Prediction equations for basal energy expenditure (BEE) were developed from these studies. The expressed purpose of these equations was to establish normal standards to serve as a benchmark for comparison with BEE of persons with various disease states such as diabetes, thyroid, and other febrile diseases. The Harris-Benedict equations remain the most common method for calculating BEE for clinical and research purposes. The widespread use of the equations and the relative inaccessibility of the original work highlights the importance of reviewing the data from which the standards were developed. A review of the data reveals that the methods and conclusions of Harris and Benedict appear valid and reasonable, albeit not error free. All of the variables used in the equations have sound physiologic basis for use in predicting BEE. Supplemental data from the Nutrition Laboratory indicates that the original equations can be applied over a wide range of age and body types. The commonly held assumption that the Harris-Benedict equations overestimate BEE in obese persons may not be true for persons who are moderately obese.

Metabolic syndrome: its history, mechanisms, and limitations

In late twentieth century, Ruderman and Reaven showed that insulin resistance might be fundamental to metabolic syndrome (MetS) which means a constellation of obesity-related metabolic derangements predisposing to type 2 diabetes and cardiovascular disease. In 2001, user-friendly National Cholesterol Education Program (NCEP) criteria of MetS were proposed. In 2005, the International Diabetes Federation (IDF) and the Examination Committee for Criteria of Metabolic Syndrome in Japan issued different criteria of MetS where abdominal obesity is a necessary component. In 2009, IDF, National Heart, Lung, and Blood Institute, American Heart Association, World Heart Federation, International Atherosclerosis Society, and International Association for the Study of Obesity jointly adopted the revised NCEP criteria, where abdominal obesity is not a necessary component, as worldwide criteria of MetS. In 2010, WHO Expert Consultation warned that MetS is a concept that focuses attention on complex multifactorial health problems but has limited practical utility as a management tool. In animal studies, adipose tissue inflammation characterized by an increased number of crown-like structures in adipose tissue, rather than obesity per se, was shown to be a fundamental mechanism of metabolic derangements.

The Canadian obesity epidemic: an historical perspective

OBJECTIVE

To examine temporal trends in stature, body mass, body mass index (BMI), and the prevalence of overweight and obesity in Canada.

RESEARCH METHODS AND PROCEDURES

Data for adults 20 to 64 years of age were compared across eight Canadian surveys conducted between 1953 and 1998. Temporal trends in stature and body mass were examined using regression, and changes in weight-for-height were expressed as changes from 1953. BMI data were available from 1970 to 1972 to examine changes in overweight and obesity. Qualitative changes in the BMI distribution were examined using Tukey mean-difference plots.

RESULTS

Significant temporal trends in stature and body mass have occurred since 1953 in Canada. Median stature increased 1.4 cm/decade in men and 1.1 cm/decade in women, whereas median body mass increased 1.9 kg/decade in men and 0.8 kg/decade in women. Increases in the 75th percentile of body mass were larger than the median. The average weight-for-height increased 5.1% in men and 4.9% in women from 1953. Furthermore, the prevalences of overweight and obesity have increased from 40.0% and 9.7% in 1970-1972 to 50.7% and 14.9% in 1998, respectively. The entire BMI distribution has shifted to the right since 1970-1972 and has become more skewed to the right for men than for women.

DISCUSSION

There have been significant increases in stature and body mass in Canada over the last 45 years. Body mass has increased more than stature, particularly in the upper percentiles, which has resulted in the currently observed high prevalences of overweight and obesity.

Trends in cardiometabolic risk factors in the Americas between 1980 and 2014: a pooled analysis of population-based surveys

BACKGROUND

Describing the prevalence and trends of cardiometabolic risk factors that are associated with non-communicable diseases (NCDs) is crucial for monitoring progress, planning prevention, and providing evidence to support policy efforts. We aimed to analyse the transition in body-mass index (BMI), obesity, blood pressure, raised blood pressure, and diabetes in the Americas, between 1980 and 2014.

METHODS

We did a pooled analysis of population-based studies with data on anthropometric measurements, biomarkers for diabetes, and blood pressure from adults aged 18 years or older. A Bayesian model was used to estimate trends in BMI, raised blood pressure (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg), and diabetes (fasting plasma glucose ≥7·0 mmol/L, history of diabetes, or diabetes treatment) from 1980 to 2014, in 37 countries and six subregions of the Americas.

FINDINGS

389 population-based surveys from the Americas were available. Comparing prevalence estimates from 2014 with those of 1980, in the non-English speaking Caribbean subregion, the prevalence of obesity increased from 3·9% (95% CI 2·2-6·3) in 1980, to 18·6% (14·3-23·3) in 2014, in men; and from 12·2% (8·2-17·0) in 1980, to 30·5% (25·7-35·5) in 2014, in women. The English-speaking Caribbean subregion had the largest increase in the prevalence of diabetes, from 5·2% (2·1-10·4) in men and 6·4% (2·6-10·4) in women in 1980, to 11·1% (6·4-17·3) in men and 13·6% (8·2-21·0) in women in 2014). Conversely, the prevalence of raised blood pressure has decreased in all subregions; the largest decrease was found in North America from 27·6% (22·3-33·2) in men and 19·9% (15·8-24·4) in women in 1980, to 15·5% (11·1-20·9) in men and 10·7% (7·7-14·5) in women in 2014.

INTERPRETATION

Despite the generally high prevalence of cardiometabolic risk factors across the Americas, estimates also showed a high level of heterogeneity in the transition between countries. The increasing prevalence of obesity and diabetes observed over time requires appropriate measures to deal with these public health challenges. Our results support a diversification of health interventions across subregions and countries.

FUNDING

Wellcome Trust.

Disparities in neighborhood food environments: implications of measurement strategies

Public health researchers have begun to map the neighborhood “food environment” and examine its association with the risk of overweight and obesity. Some argue that “food deserts”—areas with little or no provision of fresh produce and other healthy food—may contribute to disparities in obesity, diabetes, and related health problems. While research on neighborhood food environments has taken advantage of more technically sophisticated ways to assess distance and density, in general, it has not considered how individual or neighborhood conditions might modify physical distance and thereby affect patterns of spatial accessibility. This study carried out a series of sensitivity analyses to illustrate the effects on the measurement of disparities in food environments of adjusting for cross-neighborhood variation in vehicle ownership rates, public transit access, and impediments to pedestrian travel, such as crime and poor traffic safety. The analysis used geographic information systems data for New York City supermarkets, fruit and vegetable markets, and farmers' markets and employed both kernel density and distance measures. We found that adjusting for vehicle ownership and crime tended to increase measured disparities in access to supermarkets by neighborhood race/ethnicity and income, while adjusting for public transit and traffic safety tended to narrow these disparities. Further, considering fruit and vegetable markets and farmers' markets, as well as supermarkets, increased the density of healthy food outlets, especially in neighborhoods with high concentrations of Hispanics, Asians, and foreign-born residents and in high-poverty neighborhoods.

Weight management in obesity - past and present

AIMS

To describe the treatment of obesity from ancient times to present day.

METHODS

Articles reporting the development of anti-obesity therapies were identified through a search for 'anti-obesity' AND 'pharmacotherapy' AND 'development' within the title or abstract on PubMed and 'obesity' in ClinicalTrials.gov. Relevant articles and related literature were selected for inclusion.

RESULTS

Stone-age miniature obese female statuettes indicate the existence and cultural significance of obesity as long as 30,000 years ago. Records from Ancient Egyptian and Biblical eras through Greco-Roman to Medieval times indicate that obesity was present throughout the major periods of history, although peoples of previous centuries would probably have experienced overweight and obesity as exceptional rather than normal. Health risks of obesity were noted by the Greek physician Hippocrates (460-377 BCE) when the earliest anti-obesity recommendations on diet, exercise, lifestyle and use of emetics and cathartics were born. These recommendations remained largely unchanged until the early 20th century, when spreading urbanisation, increasingly sedentary jobs and greater availability of processed foods produced a sharp rise in obesity. This led to the need for new, more effective, ways to lose weight, to address comorbidities associated with obesity, and to attain the current cultural ideal of slimness. Drug companies of the 1940s and 1950s produced a series of anti-obesity pharmacotherapies in short succession, based largely on amphetamines. Increased regulation of drug development in the 1960s and new efficacy requirements for weight-loss drugs led to rapid reduction in anti-obesity therapies available by the early 1990s.

CONCLUSION

In the last two decades, several new and emerging therapies have been approved or are in development to provide safe, long-term pharmacological agents for the treatment of obesity.

A history of obesity, or how what was good became ugly and then bad

Chronic food shortage and malnutrition have been the scourge of humankind from the dawn of history. The current worldwide epidemic of obesity, now recognized as a public health crisis, is barely a few decades old. Only after the technological advances of the eighteenth century did a gradual increase in food supply became available. The initial effect of these advances in improved public health and amount, quality, and variety of food was increased longevity and body size. These early favorable outcomes of technological advances notwithstanding, their incremental effect since the Second World War has been an overabundance of easily accessible food, coupled with reduced physical activity, that accounts for the recent increased prevalence of obesity. Obesity as a chronic disease with well-defined pathologic consequences is less than a century old. The scarcity of food throughout most of history had led to connotations that being fat was good, and that corpulence and increased "flesh" were desirable as reflected in the arts, literature, and medical opinion of the times. Only in the latter half of the nineteenth century did being fat begin to be stigmatized for aesthetic reasons, and in the twentieth century, its association with increased mortality was recognized. Whereas early reports listed obesity as a risk factor for mortality from "chronic nephritis," the subsequent recognition of the more common association of obesity with diabetes, hypertension, and heart disease altered the listings and questioned its being a risk factor for kidney disease. An enlarging body of evidence, accrued over the past decade, now indicates a direct association of obesity with chronic kidney disease and its outcomes.

Secular declines in the association between obesity and mortality in the United States

Recent research suggests that rising obesity will restrain future gains in US life expectancy and that obesity is an important contributor to the current shortfall in us longevity compared to other high-income countries. Estimates of the contribution of obesity to current and future national-level mortality patterns are sensitive to estimates of the magnitude of the association between obesity and mortality at the individual level. We assessed secular trends in the obesity/mortality association among cohorts of middle-aged adults between 1948 and 2006 using three long-running US data sources: the Framingham Heart Study, the National Health and Nutrition Examination Survey, and the National Health Interview Survey. We find substantial declines over time in the magnitude of the association between obesity and overall mortality and, in certain instances, cardiovascular-specific mortality. We conclude that estimates of the contribution of obesity to current national-level mortality patterns should take into account recent reductions in the magnitude of the obesity and mortality association.

A historical analysis of public health, the law, and stigmatized social groups: the need for both obesity and weight bias legislation

History teaches that discrimination against socially undesirable groups leads to societal and governmental neglect of the stigmatized group's health problem. By placing weight discrimination in a historical context, this article demonstrates that legislation specifically aimed at rectifying obesity is less likely while weight bias is socially acceptable. Beyond obesity legislation, public health professionals may consider advocating for legislation directly targeting discrimination based on weight. This article reviews the history of discrimination against distinct groups and provides statutory solutions for discrimination based on weight. In addition to revising current statutes and regulatory rules, a unique statute targeting weight bias in the employment context is considered.

Pharmacotherapy of obesity

The growing recognition of the health risks of obesity coupled with the difficulties in treating it successfully by lifestyle modification predicates a need for effective drug treatment. The history of drug treatment in the second half of the 20th century is, however, one of disappointment and concern over drug toxicity. However, the advances in our understanding of the mechanism of weight control, together with improved ways of evaluating anti-obesity drugs, has resulted in two effective compounds, sibutramine and orlistat, becoming available for clinical use. Sibutramine has actions on both energy intake and expenditure and had been shown to enhance weight loss and weight maintenance achieved by diet, in simple obesity as well as when accompanied by complications of diabetes or hypertension. About 50-80% of patients can achieve a >5% loss, significantly more than if patients receive the same lifestyle intervention with placebo. Orlistat, which acts peripherally to block the absorption of dietary fat, has had similar results in clinical trials; a recent study (XENDOS) has just reported results which show that the enhanced, albeit modest, weight loss achieved with orlistat delays the development of diabetes over a 4-year period. A number of other compounds are expected to complete or enter clinical trials over the next decade. There is considerable optimism that we will soon have the pharmacological tools needed to make the treatment of obesity feasible.

One hundred years of growth: the evolution of height, mass, and body composition in Australian children, 1899-1999

This paper summarizes 41 reports on the height and mass of Australian children aged between 5.00 and 16.99 years between 1899 and 1999. In all, data on 644,613 children were collated, including individual data on 68,196 children. After primary data treatment to correct for methodological and statistical artifacts, regressions were calculated to quantify the rate of change of height and mass over time. Distributional analysis was used to probe for changes in skewness of mass values, indicative of differentially greater increases at higher percentiles. In addition, studies reporting skin fold measurements were analyzed to assess changes in subcutaneous adiposity since 1976. The results show that height has been increasing at a rate of about 1.02 cm.decade(-1), and mass at a rate of about 0.99 kg.decade(-1). The height and mass of children continue to increase, after a slowing down in the rate of increase between 1950 and 1980. Increases in mass at the higher percentiles have been much greater than at lower percentiles, particularly since the mid-1980s, suggesting that the incidence of obesity is increasing in Australian children. Furthermore, a steady linear increase in subcutaneous skin fold thicknesses since 1976 suggests that the overall level of fatness is increasing in Australian children. These findings indicate that Australian children are following trends becoming evident elsewhere in the developed world, and that we may see an increasingly large subset of increasingly obese children in the early years of the 21st century.

For Researchers on Obesity: Historical Review of Extra Body Weight Definitions

Rationale. The concept of obesity has been known since ancient world; however, the current standard definition of obesity was endorsed only about a decade ago. There is a need for researches to understand multiple approaches to defining obesity and how and why the standard definition was developed. The review will help to grasp the complexity of the problem and can lead to novel hypotheses in obesity research. Objective. This paper focuses on the objective to understand historical background on the development of "reference and standard tables" of weight as a platform for normal versus abnormal body weight definition. Methods. A systematic literature review was performed to chronologically summarize the definition of body weight from time of Hippocrates till the year of 2010. Conclusion. This paper presents the historical background on the development of "reference and standard tables" of weight as a platform for normal versus abnormal body weight definition. Knowledge of historical approaches to the concept of obesity can motivate researchers to find new hypotheses and utilize the appropriate obesity assessments to address their objectives.

Changes in diagnosed diabetes, obesity, and physical inactivity prevalence in US counties, 2004-2012

Recent studies suggest that prevalence of diagnosed diabetes in the United States reached a plateau or slowed around 2008, and that this change coincided with obesity plateaus and increases in physical activity. However, national estimates can obscure important variations in geographic subgroups. We examine whether a slowing or leveling off in diagnosed diabetes, obesity, and leisure time physical inactivity prevalence is also evident across the 3143 counties of the United States. We used publicly available county estimates of the age-adjusted prevalence of diagnosed diabetes, obesity, and leisure-time physical inactivity, which were generated by the Centers for Disease Control and Prevention (CDC). Using a Bayesian multilevel regression that included random effects by county and year and applied cubic splines to smooth these estimates over time, we estimated the average annual percentage point change (APPC) from 2004 to 2008 and from 2008 to 2012 for diabetes, obesity, and physical inactivity prevalence in each county. Compared to 2004-2008, the median APPCs for diabetes, obesity, and physical inactivity were lower in 2008-2012 (diabetes APPC difference = 0.16, 95%CI 0.14, 0.18; obesity APPC difference = 0.65, 95%CI 0.59, 0.70; physical inactivity APPC difference = 0.43, 95%CI 0.37, 0.48). APPCs and APPC differences between time periods varied among counties and U.S. regions. Despite improvements, levels of these risk factors remained high with most counties merely slowing rather than reversing, which suggests that all counties would likely benefit from reductions in these risk factors. The diversity of trajectories in the prevalence of these risk factors across counties underscores the continued need to identify high risk areas and populations for preventive interventions. Awareness of how these factors are changing might assist local policy makers in targeting and tracking the impact of efforts to reduce diabetes, obesity and physical inactivity.

Ancient origins of low lean mass among South Asians and implications for modern type 2 diabetes susceptibility

Living South Asians have low lean tissue mass relative to height, which contributes to their elevated type 2 diabetes susceptibility, particularly when accompanied by obesity. While ongoing lifestyle transitions account for rising obesity, the origins of low lean mass remain unclear. We analysed proxies for lean mass and stature among South Asian skeletons spanning the last 11,000 years (n = 197) to investigate the origins of South Asian low lean mass. Compared with a worldwide sample (n = 2,003), South Asian skeletons indicate low lean mass. Stature-adjusted lean mass increased significantly over time in South Asia, but to a very minor extent (0.04 z-score units per 1,000 years, adjusted R2 = 0.01). In contrast stature decreased sharply when agriculture was adopted. Our results indicate that low lean mass has characterised South Asians since at least the early Holocene and may represent long-term climatic adaptation or neutral variation. This phenotype is therefore unlikely to change extensively in the short term, so other strategies to address increasing non-communicable disease rates must be pursued.

Historical perspective: visceral obesity and related comorbidity in Joannes Baptista Morgagni's 'De sedibus et causis morborum per anatomen indagata'

In recent years, advances in epidemiological approaches and laboratory technology, along with the availability of sophisticated imaging methods to evaluate body fat distribution, made it possible to define the close correlation between visceral fat accumulation and the occurrence of metabolic abnormalities, cardiovascular diseases and respiratory disturbances in obese patients. Some 250 y ago, JB Morgagni with the help of only a knife for anatomical dissection, an acute mind, and an observational skillfulness was able to identify the intra-abdominal and mediastinal fat accumulation in android obesity. He clearly described the association between visceral obesity, hypertension, hyperuricemia, atherosclerosis and obstructive sleep apnea syndrome, long before the modern recognition of this syndrome.

Population trends and variation in body mass index from 1971 to 2008 in the Framingham Heart Study Offspring Cohort

Objective

We examined body mass index (BMI) across place and time to determine the pattern of BMI mean and standard deviation trajectories.

Methods

We included participants in the Framingham Heart Study (FHS) Offspring Cohort over eight waves of follow-up, from 1971 to 2008. After exclusions, the final sample size was 4569 subjects with 28,625 observations. We used multi-level models to examine population means and variation at the individual and neighborhood (census tracts) levels across time with measured BMI as the outcome, controlling for individual demographics and behaviors and neighborhood poverty. Because neighborhoods accounted for limited BMI variance, we removed this level as a source of variation in final models. We examined sex-stratified models with all subjects and models stratified by sex and baseline weight classification.

Results

Mean BMI increased from 24.0 kg/m² at Wave 1 to 27.7 at Wave 8 for women and from 26.6 kg/m² to 29.0 for men. In final models, BMI variation also increased from Waves 1 to 8, with the standard deviation increasing from 4.18 kg/m² to 6.15 for women and 3.31 kg/m² to 4.73 for men. BMI means increased in parallel across most baseline BMI weight classifications, except for more rapid increases through middle-age for obese women followed by declines in the last wave. BMI standard deviations also increased in parallel across baseline BMI classifications for women, with greater divergence of BMI variance for obese men compared to other weight classifications.

Conclusion

Over nearly 40 years, BMI mean and variation increased in parallel across most baseline weight classifications in our sample. Individual-level characteristics, especially baseline BMI, were the primary factors in rising BMI. These findings have important implications not only for understanding the sources of the obesity epidemic in the United States but also for the targeting of interventions to address the epidemic.