Secular trends in body mass in the United States, 1960-1980

Who are the weight maintainers?

To characterize people who maintain weight over long periods of time, normal weight and obese adults (n = 385) were studied over five annual visits. Subjects were classified using a +/- 5 lb change between the first and the fifth year visits to determine overall maintenance (M), with gain (G) or loss (L) being any change outside this range. This MGL status was cross-tabulated with a Fluctuation Index which counted the number of successive year-to-year weight changes of more than +/- 5 lbs (F0 through F4). True maintainers were defined as those having all weight changes within +/- 5 lbs during the 5-year period (M and F0). Nineteen percent (n = 73) of the subjects were classified as True Maintainers and included three times as many normal weight as obese subjects. Obese subjects comprised only 25% of the True Maintainer group but 60% of the Non-Maintainer group. Age had no association with Maintainer status. Standard measures of weight variability were lowest among True Maintainers and highest in Non-Maintainers. In addition, True Maintainers had lower BMI, Percent Body Fat, and Waist-Hip Ratios than Non-Maintainers. Subjects classified as Non-Maintainers were more likely to engage in dieting, by a variety of measures, than True Maintainers--this was particularly true among obese subjects. Finally, changes in total cholesterol, LDL and HDL cholesterol, and systolic and diastolic blood pressure were not reliably associated with Maintainer status, although the ordering of the group means suggested that True Maintainers had slightly healthier levels of "risk" variables. Overall, the results suggest that True Maintainers comprise a potentially important and interesting group of individuals who need further study.

A study of pattern of body mass index (BMI) and prevalence of obesity in a Saudi population

The present study was conducted to assess the pattern of body mass index (BMI) prevalence of obesity, and the association between obesity and other health-related problems in a Saudi population. The study was conducted in Queza district of Jeddah, Saudi Arabia. A systematic random sample of Saudi nationals aged 16 years and above were selected (total number 1037; 611 males and 426 females). The study population was clinically examined and a specially-designed questionnaire was administered to obtain the information. Anthropometric measurements, blood pressure and urine analysis were carried out. The collected data were analyzed using simple as well as multivariate statistical methods. It was observed that BMI significantly increased with age. The crude mean BMI was significantly greater in females compared to males. Prevalence of Grade I obesity among different age groups in males ranged from 15.7% to 43.0%, while in females the range was from 22.8% to 45.7%. Similar patterns for both genders were found for Grade II obesity (5.2%-18.9%; and 11.1%-47.8% respectively). Obesity was significantly associated with an increase in both systolic and diastolic blood pressure, where increase in BMI by one unit increased systolic blood pressure by 0.617 mm Hg, and diastolic blood pressure by 0.484 mm Hg. This relationship held true even after allowing for other confounding factors. The present study concluded that obesity is a problem prevalent in the community of Queza district. It is recommended that health education programs be implemented through primary health care services in the community to prevent this problem.

Trends in cancer incidence in Connecticut, 1935-1991

BACKGROUND

This study used data from the population-based Connecticut Tumor Registry, a unique resource for examining secular trends in cancer incidence rates since 1935.

METHODS

Trends in average annual age-standardized incidence rates (ASRs) for invasive cancers in Connecticut residents were examined from 1935-1939 to 1990-1991.

RESULTS

Trends in ASRs were complex, with some sites showing large increases but others only small changes since 1935-1939. Declines were evident for stomach and cervical since 1935-1939 and for colorectal cancer after 1980-1984. Since 1965-1969, when 2% or less of cancers were ascertained only by death certificates, exclusion of cancers of the breast and prostate (strongly affected by increased screening), smoking-related cancers, and cancers of other sites with identified causes (melanoma and human immunodeficiency virus-related cancers), resulted in little or no increase in the ASRs for all other sites combined. For young (20-44-year-old) adults, unexplained increases since 1965-1969 were limited to testicular cancer and Hodgkin's disease.

CONCLUSIONS

Reducing cancer incidence rates will require expanded primary prevention efforts (mainly involving behavioral changes) and more etiologic research on common cancers whose causes are poorly understood (e.g., breast and prostate cancer) and rarer cancers showing unexplained recent increases (i.e., testicular cancer and Hodgkin's disease).

Associations of body mass and body fat distribution with parity among African-American and Caucasian women: The CARDIA Study

Associations of parity with body fat and its distribution are poorly understood; therefore, we examined the relationships between parity and obesity in young adult women. Body mass index (BMI), skin-folds, and waist-hip ratio were compared in 1452 African-American and 1268 Caucasian nonpregnant women aged 18 to 30, adjusting for age (where no age-parity interactions were present), education, physical activity (assessed by questionnaire) and fitness (assessed by graded exercise test), dietary fat intake, alcohol and smoking. Adjusted mean BMI was significantly higher in African-American women aged 25-30 years with three or more children (28.5 kg/m2) than in those with two (27.0 kg/m2), one (26.2 kg/m2), or no children (26.3 kg/m2). Similar trends were found in Caucasians (BMI = 23.3, 23.4, 23.7, 25.0 kg/m2 for parity = 0, 1, 2, > or = 3, respectively), but the mean BMI was significantly higher in African Americans in each parity group. The association between BMI and parity was not present among women 18-24 years of age. Skinfolds were directly associated with parity in African Americans only. Waist-hip ratios were generally lower among nulliparous than parous women in both ethnic groups; race differences were present only among nulliparas. In conclusion, parity was associated with BMI in women aged 25 to 30 years but did not explain ethnicity-related differences in body mass.

High temporal, geographic, and income variation in body mass index among adults in Brazil

OBJECTIVES

Population-based data on body mass index for developing countries are scarce. Body mass index data from two Brazilian surveys were examined to determine regional and temporal variations in the prevalences of underweight, overweight, and obesity.

METHODS

Nationwide surveys in 1974/75 and 1989 collected anthropometric data in Brazil from 55,000 and 14,455 households, respectively. Trained interviewers used the same methods to measure weight and stature in both surveys, and survey designs were identical. Prevalences of underweight, overweight, and obesity were determined for persons 18 years of age and older.

RESULTS

In the 1989 survey, body mass index varied greatly according to region of the country, urbanization, and income. In the wealthier South, the prevalence of overweight/obesity was the highest and the prevalence of underweight was the lowest; in the poorer rural Northeast, these patterns were reversed. For both surveys, overweight/obesity was more common among women than among men and peaked at age 45 to 64 years in both sexes. Over the 15 years between surveys, the prevalence of both overweight and obesity increased strikingly.

CONCLUSIONS

In contrast to findings in developed countries, obesity in Brazil was positively associated with income and was much more prevalent among women than among men. For Brazilian women, the overall prevalence of overweight was nearly as high as that among women in the United States.

Impact of the menopause on the epidemiology and risk factors of coronary artery heart disease in women

Cardiovascular disease is the leading cause of morbidity and mortality in women, and coronary artery heart disease (CHD) is the largest single component of fatal cardiovascular disease. Gender-related differences are observed in the symptomatology, natural course and outcome, and in the management of the acute coronary event. More women, compared to men, have angina as their first manifestation of CHD, and they are less likely to have serious stenosis. Women undergo less invasive diagnostic procedures, but have an overall prognosis that is worse than that of men. Rates of CHD in women increase after the fifth-sixth decades of life, suggesting that young women have a protective factor that is lost after the fifth decade. Because most women become menopausal during this age range, it is speculated that the protective factor may the female hormone, estrogen. This conclusion is supported by results of epidemiological studies indicating an increased risk of CHD in women with early-onset menopause and a reduced risk in postmenopausal women treated with estrogen replacement therapy. The impact of the menopausal transition on other CHD risk factors is still not fully understood. Reduced estrogen levels resulting from the menopausal transition have been implicated in adverse effects on obesity and fat distribution, plasma lipid profile, and rheological properties of plasma and platelet function. Postmenopausal estrogen deficiency may also aggravate preexisting diabetes mellitus and hypertension, and have an overall negative effect on the reaction to stress. These data suggest that estrogen deficiency can directly and indirectly promote CHD in women. More research is needed to clarify and differentiate menopause-related from aging-related effects on the risk of CHD women.

Effect of race on perception of fat alone and in combination with sugar

Two studies were performed to assess the perception of sugar-fat combinations and fat emulsions in African-American and white subjects. In the first study, African-American children aged 9-15 years were found to prefer higher concentrations of sweetness in liquid dairy products varying in fat content than white children. No significant differences in preference for the four fat levels were found. These data are consistent with a previous study by Desor et al. (2) that suggested African-American youngsters aged 9-15 preferred greater sweetness in water solutions. In a second study, thresholds and preferences for corn oil and butterfat in emulsions were determined for young adults. No significant differences between African-American and white young adults were found.

The weight and fitness status of United States children

Although the prevalence of overweight and obesity among US children is a concern for many health care professionals, incidence rates over time seem to be variable, depending on the assessment measurements used. It is difficult to determine the associated health implications of pediatric obesity or overweight, especially the type that might result in adult obesity or overweight. This review examines the various factors that contribute to the weight and fitness status of children, including anthropometric factors, nutrient intake, the level of physical activity, and nutrition knowledge. Nutrient intake data of the past decade show that the energy and fat intakes of children in the United States have been fairly constant. However, data also indicate that their physical activity has declined. The data strongly suggest that the apparent prevalence of pediatric overweight may not be so much a function of nutrient intake as of a decrease in physical activity leading to an imbalance of energy input and output.

Risk factors for obesity in young adults: Hispanics, African Americans and Whites in the transition years, age 16-28 years

Previous studies have suggested that late adolescence may represent a critical period in the development of lifelong obesity, but representative prospective studies in this age group are lacking. The analytic cohort consisted of a representative sample from the United States of 11,591 Hispanic, African American, and white youths interviewed as part of the National Longitudinal Survey of Youth. Significant differences in obesity measures were observed among the six race-sex groups. Compared to whites of the same sex, the prevalence of obesity in 1981 was significantly higher among Hispanic males (12.0 vs 8.6%, P < 0.05) and African American females (14.2% vs 7.3%, P > 0.001) and lower among African American males (6.4% vs 8.6%, P > 0.005). Five-year cumulative incidence of obesity (1981-1986) was highest in Hispanic males, Hispanic females and African American females. Among those ages studied both in 1981 and in 1986, a secular trend towards increased prevalence of obesity was observed over the five-year period (10.6% in 1981, 13.6% in 1986, P > 0.0001). Multivariate analyses failed to identify behavioral or sociodemographic factors that operated similarly in all race-sex groups.

Obesity in Pima Indians: large increases among post-World War II birth cohorts

Several studies have shown secular increases in obesity during the past 35 years, and others have reported increases in dietary fat consumption during the same period. Here we report a dramatic increase in obesity among Pima Indians born after World War II that appears to be associated with increased exposure to Western customs and diet following 1945. We examined the body mass index (BMI = weight in kilograms/height2 in meters) of 1,128 male and 1,372 female Pima Indians aged 15-65 years who were born between 1901 and 1964 and were examined between 1965 and 1990. We found large increases in BMI among Pima Indian men and women in post-World War II birth cohorts (1945 and later). The parallel changes in body mass index, dietary fat, and exposure to Western culture following World War II suggest that culturally mediated changes in diet and level of physical activity associated with modern industrialized society may have led to the large increases in obesity in the Pima Indians and to smaller parallel changes observed worldwide in westernized countries.

Trends in body mass index and prevalence of obesity in Swedish women 1980-89

STUDY OBJECTIVE

To assess changes in the body mass index (BMI, weight (kg)/height2 (m2)) and in the prevalence of obesity in Swedish women during the 1980s.

DESIGN

Data from two successive cross sectional surveys were used.

SETTING

The whole of Sweden.

SUBJECTS

A total of 7419 women from a 1980-81 survey (response rate 84.6%) and 6306 women from a 1988-89 survey (response rate 80.3%), aged 16-84 years, and forming a representative sample of Swedish women.

MEASUREMENTS AND MAIN RESULTS

The results were based on self reported weight and height during interview. The mean BMI of the whole population, adjusted for age, education level, socioeconomic group, region, and nationality, increased by 0.17 kg/m2 (p = 0.0056) over the eight year period. The increase was particularly pronounced in the group aged 25-34 years (0.74 kg/m2; p < 0.0001, which corresponds to more than 2 kg for a woman 168 cm tall). The higher mean BMI was also reflected in the relative increase in the prevalence of obesity (BMI > 28.6 kg/m2) by 19% (odds ratio (OR) = 1.19; 95% confidence interval (CI): 1.04, 1.37) and of the combination of overweight and obesity (BMI > 23.8 kg/m2) by 12% (OR = 1.12; 95% CI 1.03, 1.23) in the whole female population.

CONCLUSIONS

During the 1980s the mean BMI and the prevalence of overweight and obesity in adult Swedish women increased. An influence of the sociocultural environment on the body weight in women was stronger than that in men.

Trends in body mass index and prevalence of obesity in Swedish men 1980-89

STUDY OBJECTIVE

To assess changes in the body mass index (BMI, weight (kg)/height2 (m2) and in the prevalence of obesity in Swedish men during the 1980s.

DESIGN

Data from two successive cross sectional surveys were used.

SETTING

The whole of Sweden.

PARTICIPANTS

Subjects included in the analyses were 7055 men from a 1980-81 survey (response rate 83.4%) and 6081 men from a 1988-89 survey (response rate 79%). Men were aged 16-84 years and were a representative sample of Swedish males.

MEASUREMENTS AND MAIN RESULTS

The results were based on self reported weight and height obtained during interview. After adjustment for sociodemographic variables, a significant increase in the mean BMI of the entire population of men was found between 1980-81 and 1988-89 (0.23 kg/m2; p < 0.001), with a particularly large increase in the 25-34 year age group (0.45 kg/m2; p < 0.0001) which corresponds to 1.4 kg for a man 180 cm tall). In manual workers this value was 0.25 kg/m2 (p < 0.0005). This increase was also reflected by a significant relative increase in the prevalence of the combination of overweight and obesity (BMI > 25 kg/m2) of about 19% (odds ratio = 1.19, 95% confidence intervals: 1.09, 1.29).

CONCLUSIONS

During the 1980s the mean BMI and the prevalence of overweight and obesity among adult Swedish men increased.

Defining obesity in children and adolescents: epidemiologic approaches

This article discusses the use of epidemiologic and statistical approaches in developing definitions of obesity for children and adolescents. Definitions of adult obesity have been derived from mortality data or from statistical data on reference populations. Both approaches pose problems when applied to children and adolescents. The choice of appropriate measurements can be difficult. Data on childhood weight and adult outcomes are sparse and hard to interpret. Statistical definitions based on reference populations are more straightforward, but require arbitrary assumptions that limit their usefulness for prevalence estimates or comparisons across age, sex, or race/ethnic groups. Examples illustrate some issues in defining childhood obesity, including a case study of two groups of researchers who used the same data sets, but arrived at different conclusions. At present there is no generally accepted objective definition of obesity for children or adolescents.

Trends in body composition for infants and children in the U.S

Nationally representative health examination surveys have collected anthropometric measurements on children and adolescents in the U.S. These data may serve as very crude indicators of total fat or fat-free body mass, but do not yield information on body composition per se. Attempts to accurately describe trends in obesity for children and adolescents have been complicated by a number of limitations associated with body measurements taken over time in sequential surveys. Inferences from limited anthropometric measures should be made cautiously. Factors to consider include the selection of cutpoints for trend analysis, changes that may be within range of technical measurement error, and use of data at extreme percentiles. Ostensible trends may be genuine, but they may also be influenced by methodological differences across surveys. Comparative data are presented for selected body measures from 1963 to 1980 for U.S. children and adolescents sampled in national health examination surveys, and apparent differences are discussed.

Ethnic variation in the prevalence of obesity in North American children and youth

The estimated prevalence of obesity in North American children and youth (6 to 17 years) in the 1960s through the 1980s is reported. Use of the triceps skinfold and BMI independently and in combination as indicators of obesity provides different estimates of prevalence due to ethnicity. With the triceps skinfold as the indicator, there is an increase in the prevalence of obesity and a reduction in variation between Black and White children and youth from the 1960s to 1980; however, with the BMI as the indicator, there is no change in the prevalence of obesity and negligible ethnic difference in these national data sets. On the other hand, the prevalence of obesity has increased over time in Mexican American and American Indian children and youth. Data for American children and youth of Asiatic ancestry are limited.

Tibia vara: a complication of adolescent obesity

Tibia vara is characterized by inhibited growth of the medial portion of the proximal tibial growth plate, leading to progressive bowleg deformity. Twenty-nine adolescent patients with this condition were reviewed: all were black, 27 (93%) were male, and 19 (66%) had only one side affected. Progressive deformity rather than knee discomfort was the most common presenting complaint. The deformity reportedly developed rapidly during the adolescent growth spurt. The body weights of these patients exceeded the 95th percentile for age and gender by an average of 43 kg. The absence of significant symptoms and a body habitus that obscured the deformity often resulted in delayed diagnosis. Physicians involved in the care of obese black male adolescents should carefully examine them for tibia vara, which has a reported prevalence of 2% to 3% in this population. Treatment options are severely restricted if the condition is not diagnosed early.

Socioeconomic and behavioral correlates of body mass index in black adults: the Pitt County Study

BACKGROUND

Obesity is more prevalent among Black women than Black men, but there is little information on the correlates of obesity in Blacks. This study describes the relations of sociodemographic factors and health behaviors to body mass index in a southern, Black population.

METHODS

In 1988, a community probability sample of 1784 Black adults, aged 25 to 50, was examined in Pitt County, NC.

RESULTS

More women than men were at least 20% overweight (57% vs 36%). The relation of socioeconomic status (a composite of education and occupation) to age-adjusted body mass index level was inverse in women but not in men. Body mass index did not differ with either current energy intake or energy expenditure. Smokers and drinkers had lower age-adjusted levels than non-smokers and abstainers.

CONCLUSIONS

Since the excess body mass index levels associated with low socioeconomic status in women could not be explained after controlling for adverse health behaviors, further epidemiologic study of risk factors for obesity in Black women is recommended.

Epidemiologic studies utilizing surveys: accounting for the sampling design

BACKGROUND

Since large-scale health surveys usually have complicated sampling schemes, there is often a question as to whether the sampling design must be considered in the analysis of the data. A recent disagreement concerning the analysis of a body iron stores-cancer association found in the first National Health and Nutrition Examination Survey and its follow-up is used to highlight the issues.

METHODS

We explain and illustrate the importance of two aspects of the sampling design: clustering and weighting of observations. The body iron stores-cancer data are reanalyzed by utilizing or ignoring various aspects of the sampling design. Simple formulas are given to describe how using the sampling design of a survey in the analysis will affect the conclusions of that analysis.

RESULTS

The different analyses of the body iron stores-cancer data lead to very different conclusions. Application of the simple formulas suggests that utilization of the sample clustering in the analysis is appropriate, but that a standard utilization of the sample weights leads to an uninformative analysis. The recommended analysis incorporates the sampling weights in a nonstandard way and the sample clustering in the standard way.

CONCLUSIONS

Which particular aspects of the sampling design to use in the analysis of complex survey data and how to use them depend on certain features of the design. We give some guidelines for when to use the sample clustering and sample weights in the analysis.

A prospective study of obesity and risk of coronary heart disease in women

We examined the incidence of nonfatal and fatal coronary heart disease in relation to obesity in a prospective cohort study of 115,886 U.S. women who were 30 to 55 years of age in 1976 and free of diagnosed coronary disease, stroke, and cancer. During eight years of follow-up (775,430 person-years), we identified 605 first coronary events, including 306 nonfatal myocardial infarctions, 83 deaths due to coronary heart disease, and 216 cases of confirmed angina pectoris. A higher Quetelet index (weight in kilograms divided by the square of the height in meters) was positively associated with the occurrence of each category of coronary heart disease. For increasing levels of current Quetelet index (less than 21, 21 to less than 23, 23 to less than 25, 25 to less than 29, and greater than or equal to 29), the relative risks of nonfatal myocardial infarction and fatal coronary heart disease combined, as adjusted for age and cigarette smoking, were 1.0, 1.3, 1.3, 1.8, and 3.3 (Mantel-extension chi for trend = 7.29; P less than 0.00001). As expected, control for a history of hypertension, diabetes mellitus, and hypercholesterolemia--conditions known to be biologic effects of obesity--attenuated the strength of the association. The current Quetelet index was a more important determinant of coronary risk than that at the age of 18; an intervening weight gain increased risk substantially. These prospective data emphasize the importance of obesity as a determinant of coronary heart disease in women. After control for cigarette smoking, which is essential to assess the true effects of obesity, even mild-to-moderate overweight increased the risk of coronary disease in middle-aged women.