The accuracy of the Goldberg method for classifying misreporters of energy intake on a food frequency questionnaire and 24-h recalls: comparison with doubly labeled water.

BACKGROUND/OBJECTIVES: Adults often misreport dietary intake; the magnitude varies by the methods used to assess diet and classify participants. The objective was to quantify the accuracy of the Goldberg method for categorizing misreporters on a food frequency questionnaire (FFQ) and two 24-h recalls (24HRs). SUBJECTS/METHODS: We compared the Goldberg method, which uses an equation to predict total energy expenditure (TEE), with a criterion method that uses doubly labeled water (DLW), in a study of 451 men and women. Underreporting was classified using recommended cut points and calculated values. Sensitivity and specificity, positive predictive value (PPV) and negative predictive value and the area under the receiver operating characteristic curve (AUC) were calculated. Predictive models of underreporting were contrasted for the Goldberg and DLW methods. RESULTS: AUCs were 0.974 and 0.972 on the FFQ, and 0.961 and 0.938 on the 24HR for men and women, respectively. The sensitivity of the Goldberg method was higher for the FFQ (92%) than the 24HR (50%); specificity was higher for the 24HR (99%) than the FFQ (88%); PPV was high for the 24HR (92%) and FFQ (88%). Simulation studies indicate attenuation in odds ratio estimates and reduction of power in predictive models. CONCLUSIONS: Although use of the Goldberg method may lead to bias and reduction in power in predictive models of underreporting, the method has high predictive value for both the FFQ and the 24HR. Thus, in the absence of objective measures of TEE or physical activity, the Goldberg method is a reasonable approach to characterize underreporting.

OPEN about obesity: recovery biomarkers, dietary reporting errors and BMI.

OBJECTIVE: Obesity-related under-reporting of usual dietary intake is one of the most persistent sources of bias in nutrition research. The aim of this paper is to characterize obese and non-obese individuals with respect to reporting errors observed with two common dietary instruments, using energy and protein recovery biomarkers as reference measures. POPULATION AND METHODS: This report employs data from the Observing Protein and Energy Nutrition (OPEN) study. Analyses are based on stratified samples of 211 (57 obese) men and 179 (50 obese) women who completed 24-h recalls (24HR), food frequency questionnaires (FFQ), doubly labelled water (DLW) and urinary nitrogen (UN) assessments. RESULTS: In obese and non-obese subgroups, FFQ yielded lower energy and protein intake estimates than 24HR, although biomarker-based information indicated under-reporting with both dietary instruments. Gender differences in obesity-related bias were noted. Among women, the DLW-based energy requirement was 378 kcal greater in obese than in non-obese groups; the FFQ was able to detect a statistically significant portion of this extra energy, while the 24HR was not. Among men, the DLW-based energy requirement was 485 kcal greater in the obese group; however, neither FFQ nor 24HR detected this difference in energy requirement. Combining protein and energy estimates, obese men significantly over-reported the proportion of energy from protein using the 24HR, but not with the FFQ. In obese women, no significant reporting error for energy percent protein was observed by either method. At the individual level, correlations between energy expenditure and reported energy intake tended to be weaker in obese than non-obese groups, particularly with the 24HR. Correlations between true and reported protein density were consistently higher than for protein or energy alone, and did not vary significantly with obesity. CONCLUSION: This work adds to existing evidence that neither of these commonly used dietary reporting methods adequately measures energy or protein intake in obese groups. The 24HR, while capturing more realistic energy distributions for usual intake, may be particularly problematic in the obese.

Precision of the doubly labeled water method in a large-scale application: evaluation of a streamlined-dosing protocol in the Observing Protein and Energy Nutrition (OPEN) study.

OBJECTIVE: To evaluate whether the doubly labeled water (DLW) method is precise under conditions required for a large-scale evaluation of dietary intake instruments. DESIGN: Energy expenditure was measured in 484 subjects (main study). Subjects received one of five different weight DLW dose bottles prepared in advance of the study. A repeat energy expenditure measure was obtained in a subset of 24 subjects (substudy). DLW measures of energy expenditure were performed over a 2-week interval with urine collection at the beginning and end. SETTING: Free-living environment with three clinic visits in the Maryland suburban area of Washington, DC. SUBJECTS: A total of 484 subjects (261 men and 223 women) aged 40-69 y, 24 of whom (13 men and 11 women) participated in a substudy in which DLW was administered a second time. RESULTS: The coefficient of variation of the DLW energy expenditure measurement was 5.1%. This included a 2.9% analytical and a 4.2% physiologic variation. Based on observed initial isotopic enrichment, the preweighed dosages were optimal in 70% of the main study subjects, and 9% received a dose that was less than optimal. Only six subjects (1%) were excluded because the final isotopic enrichment was too low to conduct precise measurement. CONCLUSIONS: Use of preweighed DLW dosages did not compromise the precision of the DLW method. The DLW method is a reliable measure of energy expenditure for large-scale evaluations of dietary intake instruments.

Evaluating the impact of population changes in diet, physical activity, and weight status on population risk for colon cancer (United States).

OBJECTIVE: To estimate the effects of observed population-level changes in risk factors on population risk and incidence of disease. METHODS: Trends in a set of risk factors for colon cancer (vegetable intake, red meat intake, alcohol consumption, physical activity levels, and weight status) were modeled for the US adult population over the years 1975-1995 and combined with relative risk estimates from epidemiologic studies and a probability distribution for the induction period to estimate the percentage change in incidence rates from 1985 to 1995 due to the five risk factors. A sensitivity analysis was performed to account for imprecision related to estimates of trends in behavior and epidemiologic risk. RESULTS: Increased vegetable intake and decreased intakes of red meat and alcohol reduced risk, while reduced physical activity and increased body mass index increased risk for colon cancer. When all five factors were considered together, change in the average population relative risk was small and the risk factors accounted for little of the recently observed decline in incidence. CONCLUSIONS: Although these factors have the potential to greatly affect risk of colon cancer and incidence rates, little of that potential was realized since adverse trends neutralized what progress had been made in the areas of vegetables, red meat, and alcohol consumption.

Television watching, energy intake, and obesity in US children: results from the third National Health and Nutrition Examination Survey, 1988-1994.

OBJECTIVES: To examine the relationship between television watching, energy intake, physical activity, and obesity status in US boys and girls, aged 8 to 16 years. METHODS: We used a nationally representative cross-sectional survey with an in-person interview and a medical examination, which included measurements of height and weight, daily hours of television watching, weekly participation in physical activity, and a dietary interview. Between 1988 and 1994, the Third National Health and Nutrition Examination Survey collected data on 4069 children. Mexican Americans and non-Hispanic blacks were oversampled to produce reliable estimates for these groups. RESULTS: The prevalence of obesity is lowest among children watching 1 or fewer hours of television a day, and highest among those watching 4 or more hours of television a day. Girls engaged in less physical activity and consumed fewer joules per day than boys. A higher percentage of non-Hispanic white boys reported participating in physical activity 5 or more times per week than any other race/ethnic and sex group. Television watching was positively associated with obesity among girls, even after controlling for age, race/ethnicity, family income, weekly physical activity, and energy intake. CONCLUSIONS: As the prevalence of overweight increases, the need to reduce sedentary behaviors and to promote a more active lifestyle becomes essential. Clinicians and public health interventionists should encourage active lifestyles to balance the energy intake of children.

Aim for a healthy weight: what is the target?

The first guideline statement of the Year 2000 edition of Nutrition and Your Health: Dietary Guidelines for Americans is "Aim for a healthy weight." The purpose of this paper is to describe the evolution of the weight guideline and discuss some issues related to it. We reviewed current and previous editions of the Dietary Guidelines and the corresponding advisory committee reports. The weight guideline has evolved over the years into one that is complex and touches on a wide range of issues. The 2000 edition emphasizes weight loss more than previous editions. Unlike the other guidelines in the Dietary Guidelines, the weight guideline has a health outcome, a "healthy" weight, rather than a behavioral outcome as its goal. Also unlike the other guidelines, the weight guideline has become more medically oriented over time. The concept of healthy weight in the guidelines includes aspects of body composition, fat distribution and weight-related health conditions. It may be difficult for the public and even for health care providers to interpret some of the concepts included in the weight guideline. Issues related to the appropriate management of weight can be complex and may require a health care provider as a resource for interpretation. Rather than try to incorporate further clinical decision-making and weight loss guidance within the weight guideline, it may be more appropriate to refer the reader to a health care provider for guidance, as was done in previous editions.

Be physically active each day. How can we know?

For the first time in its five versions, Nutrition and Your Health: Dietary Guidelines for Americans contains an apparently nondietary guideline recommending physical activity. Although new as a separate guideline, physical activity has been included in the weight guideline of previous versions. The current version recognizes the importance of physical activity to health beyond its effect on weight maintenance. The purpose of this paper is to examine what data are available or required to evaluate the level of physical activity in the population, particularly in light of current recommendations. The physical activity sections of several national surveys that assess individual behavior or activity-related policies are described. Surveillance of physical activity as a risk factor for chronic disease is critical because physical inactivity is highly prevalent, strongly associated with increased morbidity and mortality, costly and preventable. Determinants of physical activity behavior are also considered. These determinants are potentially important factors for surveillance and are critical components for planning successful interventions.

Energy and fat intakes of children and adolescents in the united states: data from the national health and nutrition examination surveys.

BACKGROUND: Dietary factors related to body weight and chronic disease risk are of interest because of recent increases in the prevalence of overweight. OBJECTIVE: Secular trends in energy and fat intakes of youths aged 2-19 y were assessed. Current intakes were compared with recommendations. DESIGN: Dietary 24-h recall data from the third National Health and Nutrition Examination Survey (1988-1994) and earlier national surveys were examined. RESULTS: Mean energy intake changed little from the 1970s to 1988-1994 except for an increase among adolescent females. Over the same time period, the mean percentage of energy from total and saturated fat decreased, but remained above recommendations, with overall means of 33.5% of energy from fat and 12.2% of energy from saturated fat. In 1988-1994, approximately 1 in 4 youths met the recommendations for intakes of fat and saturated fat and 3 in 4 met the recommendation for cholesterol intake. Beverages contributed 20-24% of energy across all ages and soft drinks provided 8% of energy in adolescents. Except for adolescent girls, beverage energy contributions were generally higher among overweight than nonoverweight youths; soft drink energy contribution was higher among overweight youths than among nonoverweight youths for all groups. CONCLUSIONS: The lack of evidence of a general increase in energy intake among youths despite an increase in the prevalence of overweight suggests that physical inactivity is a major public health challenge in this age group. Efforts to increase physical activity and decrease nonnutritive sources of energy may be important approaches to counter the rise in overweight prevalence.

Changes in the distribution of body mass index of adults and children in the US population.

BACKGROUND: National survey data show increases in mean body mass index (BMI) and in the prevalence of overweight and obesity for adults and children in the United States, indicating a change in the distribution of BMI. OBJECTIVE: To apply graphical methods to describe changes in the distribution of BMI. DESIGN: BMI values from the third National Health and Nutrition Examination Survey (NHANES III: 1988-94) were compared with data from earlier cross-sectional nationally representative surveys for adults 20-74 y of age and for children and adolescents 6-17 y of age. Tukey mean-difference plots were used to investigate the changes in the distributions of BMI within sex-age groups. RESULTS: Mean-difference plots allow qualitative visual comparisons of the distributions of BMI between surveys. For all sex-age groups, there was increasing skewness with a greater shift in the upper part of the distribution so that, within each group, the heaviest subgroup was heavier in NHANES III than in prior surveys. For the youngest children, the lower part of the distribution showed virtually no change. With increasing age the whole distribution tended to shift upward slightly, suggesting an increase in BMI across the entire population. CONCLUSIONS: These changes in the distribution of BMI suggest the combination of both profound environmental determinants and a population with a high degree of susceptibility. The reasons for the increasing prevalence of obesity should be sought in part by seeking to understand the factors causing increases in the population as a whole.

Overweight prevalence among youth in the United States: why so many different numbers?

Several recent publications have presented different estimates for the prevalence of overweight among youth in the United States. Prevalence estimates range from 11-24%, despite describing the same results from the third National Health and Nutrition Examination Survey (NHANES III). This paper discusses the variety and evolution of different overweight prevalence estimates. Issues of definition, measurements, criteria selection and comparison groups are considered and implications for estimates of the prevalence of overweight among youth are explored. Reference percentiles for body mass index (BMI) from several publications are compared. The differences in published estimates from NHANES III are noted and explained.

Overweight children and adolescents: description, epidemiology, and demographics.

We describe prevalence and trends in overweight among children and adolescents (6 to 17 years old) in the US population and variation in the prevalence by sex, age, race-ethnicity, income, and educational level. Height and weight were measured in nationally representative surveys conducted between 1963 and 1994: cycles II (1963 to 1965) and III (1966 to 1970) of the National Health Examination Survey (NHES) and the National Health and Nutrition Examination Surveys (NHANES I, 1971 to 1974; NHANES II, 1976 to 1980; and NHANES III, 1988 to 1994). Overweight was defined by the age- and sex-specific 95th percentile of body mass index (BMI) from NHES II and III. BMI values between the 85th and 95th percentiles were considered an area of concern, because at this level there is increased risk for becoming overweight. Approximately 11% of children and adolescents were overweight in 1988 to 1994, and an additional 14% had a BMI between the 85th and 95th percentiles. The prevalence of overweight did not vary systematically with race-ethnicity, income, or education. Overweight prevalence increased over time, with the largest increase between NHANES II and NHANES III. Examination of the entire BMI distribution showed that the heaviest children were markedly heavier in NHANES III than in NHES, but the rest of the distribution of BMI showed little change. Data are limited for assessing the causes of the rapid change in the prevalence of overweight. The increased overweight prevalence in US children and adolescents may be one manifestation of a more general set of societal effects. Childhood overweight should be addressed from a public health perspective.

Prevalence of overweight among preschool children in the United States, 1971 through 1994.

OBJECTIVE: To examine the prevalence of overweight among US preschool children 2 months through 5 years of age between the years 1971 through 1974 and 1988 through 1994. DESIGN: Nationally representative cross-sectional surveys with a physical examination, including measurement of stature, length, and weight. Between 1200 and 7500 children younger than 6 years were examined in each of four different surveys during 1971 through 1974 (first National Health and Nutrition Examination Survey [NHANES I]), 1976 through 1980 (NHANES II), 1982 through 1984 (Hispanic Health and Nutrition Examination Survey), and 1988 through 1994 (NHANES III). RESULTS: The prevalence of overweight increased among some sex and age groups of preschool children between 1971 through 1974 and 1988 through 1994. More than 10% of 4- and 5-year-old girls were overweight in 1988 through 1994 compared with 5.8% in 1971 through 1974. However, there was no change during this period in the prevalence of overweight among 1- and 2- to 3-year-old children. During 1988 through 1994, the prevalence of overweight among children 2 months through 5 years of age was consistently higher in girls than boys. Mexican-American children had a higher prevalence of overweight than non-Hispanic black and non-Hispanic white children. These results parallel what has been reported for older children and adults in the United States. CONCLUSION: These results show that in the last 20 years the prevalence of overweight has increased among 4- and 5-year-old children but not among younger children. These findings suggest that efforts to prevent overweight, including encouragement of physical activity and improved diets, should begin in early childhood.

Varying body mass index cutoff points to describe overweight prevalence among U.S. adults: NHANES III (1988 to 1994).

Body mass index (BMI; kg/m2) distributions are commonly reported in the scientific literature to describe weight for stature. These data are collected for various groups of subjects in local health and body composition studies, and comparisons with national distributions are often desirable. Tabular data for population prevalence estimates from the third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1994) at selected gender- and age-specific BMI levels ranging from < 18.0 to > 45.0 are presented and compared with various examples of BMI criteria reported in the scientific literature. NHANES III was a statistically representative national probability sample of the civilian, noninstitutionalized population of the United States in which height and weight were measured as part of a more comprehensive health examination. The implications of varying population prevalence estimates based on varying BMI cutoff points are briefly discussed for selected examples including World Health Organization over-weight/obesity criteria and the U.S. Dietary Guidelines for Americans. The median BMI for U.S. adults aged 20 years and older is 25.5 kg/m2. Median stature and weight for men are 175.5 cm and 80.0 kg and for women are 161.6 cm and 65.6 kg, respectively. The percentage of the population with BMI < 19.0 is 1.6% for men, 5.7% for women; BMI > or = 19.0 to < 25.0 is 39.0% for men, 43.6% for women; BMI > or = 25.0 is 59.4% for men, 50.7% for women. An estimated 97.1 million adults have a BMI > or = 25.0. Additional prevalence estimates based on other BMI cutoff points and ages are presented.

The relationship between body weight and mortality: a quantitative analysis of combined information from existing studies.

OBJECTIVE: To estimate the relationship between body mass index (BMI, kg/m2) and all-cause mortality with information from the published scientific literature. DESIGN: Meta-analysis using a hierarchical, mixed model. The analysis included random effects for information sources and fixed effects for factors that may modify the BMI-mortality relationship such as smoking, control for disease, and country of origin, which allowed combining information from diverse studies. MAIN OUTCOME MEASURES: Predicted probability of death over a given duration of follow-up plotted by BMI for sex-age cohorts of white race. RESULTS: An extensive search identified nineteen prospective cohort studies that met inclusion criteria. A U-shaped relationship between BMI and mortality was demonstrated for 50-year-old men followed for 30 years. Mortality risk increased with low and high BMI (< 23 or > 28) in groups of non-smokers without evidence of disease upon study entry. Limited information from studies of women indicated that, with 10 year follow-up, there was little relationship between BMI and mortality for (1) non-smokers and for (2) mixtures of smokers and non-smokers. CONCLUSION: This quantitative analysis of existing studies revealed increased mortality at moderately low BMI for white men comparable to that observed at extreme overweight, which does not appear to be due to smoking or existing disease. Attention to the health risks of underweight is needed, and body weight recommendations for optimum longevity need to be considered in light of these risks.

Evaluation of long-term community recovery from Hurricane Andrew: sources of assistance received by population sub-groups.

Two three-stage cluster surveys were conducted in South Dade County, Florida, 14 months apart, to assess recovery following Hurricane Andrew. Response rates were 75 per cent and 84 per cent. Sources of assistance used in recovery from Hurricane Andrew differed according to race, per capita income, ethnicity, and education. Reports of improved living situation post-hurricane were not associated with receiving relief assistance, but reports of a worse situation were associated with loss of income, being exploited, or job loss. The number of households reporting problems with crime and community violence doubled between the two surveys. Disaster relief efforts had less impact on subjective long-term recovery than did job or income loss or housing repair difficulties. Existing sources of assistance were used more often than specific post-hurricane relief resources. The demographic make-up of a community may determine which are the most effective means to inform them after a disaster and what sources of assistance may be useful.

The influence of smoking cessation on the prevalence of overweight in the United States.

BACKGROUND: The proportion of U.S. adults 35 to 74 years of age who were overweight increased by 9.6 percent for men and 8.0 percent for women between 1978 and 1990. Since the prevalence of smoking declined over the same period, smoking cessation has been suggested as a factor contributing to the increasing prevalence of overweight. METHODS: To estimate the influence of smoking cessation on the increase in the prevalence of overweight, we analyzed data on current and past weight and smoking status for a national sample of 5247 adults 35 years of age or older who participated in the third National Health and Nutrition Examination Survey, conducted from 1988 through 1991. The results were adjusted for age, sociodemographic characteristics, level of physical activity, alcohol consumption, and (for women) parity. RESULTS: The weight gain over a 10-year period that was associated with the cessation of smoking (i.e., the gain among smokers who quit that was in excess of the gain among continuing smokers) was 4.4 kg for men and 5.0 kg for women. Smokers who had quit within the past 10 years were significantly more likely than respondents who had never smoked to become overweight (odds ratios, 2.4 for men and 2.0 for women). For men, about a quarter (2.3 of 9.6 percentage points) and for women, about a sixth (1.3 of 8.0 percentage points) of the increase in the prevalence of overweight could be attributed to smoking cessation within the past 10 years. CONCLUSIONS: Although its health benefits are undeniable, smoking cessation may nevertheless be associated with a small increase in the prevalence of overweight.

Overweight prevalence and trends for children and adolescents. The National Health and Nutrition Examination Surveys, 1963 to 1991.

OBJECTIVE: To examine prevalence of overweight and trends in overweight for children and adolescents in the US population. DESIGN: Nationally representative cross-sectional surveys with an in-person interview and a medical examination, including measurement of height and weight. PARTICIPANTS: Between 3000 and 14,000 youths aged 6 through 17 years examined in each of five separate national surveys during 1963 to 1965, 1966 to 1970, 1971 to 1974, 1976 to 1980, and 1988 to 1991 (Cycles II and III of the National Health Examination Survey, and the first, second, and third National Health and Nutrition Examination Surveys, respectively). MAIN OUTCOME MEASURES: Prevalence of overweight based on body mass index and 85th or 95th percentile cutoff points from Cycles II and III of the National Health Examination Survey. RESULTS: From 1988 to 1991, the prevalence of overweight was 10.9% based on the 95th percentile and 22% based on the 85th percentile. Overweight prevalence increased during the period examined among all sex and age groups. The increase was greatest since 1976 to 1980, similar to findings previously reported for adults in the United States. CONCLUSIONS: Increasing overweight among youths implies a need to focus on primary prevention. Attempts to increase physical activity may provide a means to address this important public health problem.

Long-term effects of Hurricane Andrew: revisiting mental health indicators.

Two population-based surveys of South Dade County, Florida, were conducted after Hurricane Andrew to compare hurricane-related symptoms of mental distress and describe the impact of mental health outreach teams. Households were selected by three-stage cluster sampling and findings from the two surveys, 13 months apart, were compared. Response rates were 75 per cent and 84 per cent. The prevalence of symptoms of mental distress decreased over time. However, in the households contacted by the teams (25 per cent of sample), the prevalence of symptoms (50 per cent) did not differ from households not contacted (43 per cent). Households contacted by teams that reported symptoms were just as likely to have been referred for help by the teams (72 per cent) as those without symptoms (68 per cent). Households reporting symptoms were equally likely to get counselling regardless of whether the teams visited. Mental health teams had no significant impact on mental health symptoms or the use of mental health services. Alternative approaches to mental health outreach teams need to be explored.

Effect of dl-fenfluramine on thermic effect of food in humans.

To determine whether dl-fenfluramine increased metabolic rate in humans, hourly indirect calorimetry measurements were made on 16 nonobese males over a 5 h period under each of four conditions: placebo/no meal, placebo/meal, 60 mg dl-fenfluramine/no meal, and 60 mg dl-fenfluramine/meal. Drug administration was double-blind and a Latin square design was used with treatments separated by 7 days. To confirm that active drug was administered when assigned, subjective sensations were measured by questionnaires administered three times during each treatment. Metabolic rate (kcal/min) during the four treatments was compared by analysis of variance over the entire 5 h and at the end of the measurement period. The 750 kcal (3140 kJ) meal increased metabolic rate over the fasting conditions (0.160 +/- 0.035 kcal/min, P less than 0.0005) and the combination of fenfluramine and meal caused a further significant increase beyond that found with placebo and meal (0.072 +/- 0.035 kcal/min, P less than 0.025). At the end of the measurement period, metabolic rate during the placebo/meal treatment had returned to the level of the fasting treatments. In contrast, during the fenfluramine/meal condition, metabolic rate was still elevated (0.173 +/- 0.04 kcal/min, P less than 0.003). The results of this study suggested that fenfluramine increased metabolic rate by potentiating the thermic effect of food.