Dr. Gregory Hand has received consultancy fees from the National Institutes of Health (NIH) and grants from the NIH, and The Coca-Cola Company. Dr. James Hébert is supported by an Established Investigator Award in Cancer Prevention and Control from the Cancer Training Branch of the National Cancer Institute (K05 CA136975). Dr. Steven Blair receives book royalties (<$5,000/year) from Human Kinetics; honoraria for service on the Scientific/Medical Advisory Boards for Clarity, Technogym, Santech, and Jenny Craig; and honoraria for lectures and consultations from scientific, educational, and lay groups which are donated to the University of South Carolina or not-for-profit organizations. Dr. Blair is a consultant on research projects with the University of Texas-Southwestern Medical School and the University of Miami. During the past 5-year period Dr. Blair has received research grants from The Coca-Cola Company, the National Institutes of Health, and Department of Defense. Funding for the study was provided by an unrestricted research grant from The Coca-Cola Company. The sponsor of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the report, and does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.
Conceived and designed the experiments: EA SNB. Performed the experiments: EA. Analyzed the data: EA GAH SNB. Wrote the paper: EA.
Methodological limitations compromise the validity of U.S. nutritional surveillance data and the empirical foundation for formulating dietary guidelines and public health policies.
Evaluate the validity of the National Health and Nutrition Examination Survey (NHANES) caloric intake data throughout its history, and examine trends in the validity of caloric intake estimates as the NHANES dietary measurement protocols evolved.
Validity of data from 28,993 men and 34,369 women, aged 20 to 74 years from NHANES I (1971–1974) through NHANES 2009–2010 was assessed by: calculating physiologically credible energy intake values as the ratio of reported energy intake (rEI) to estimated basal metabolic rate (BMR), and subtracting estimated total energy expenditure (TEE) from NHANES rEI to create ‘disparity values’.
1) Physiologically credible values expressed as the ratio rEI/BMR and 2) disparity values (rEI–TEE).
The historical rEI/BMR values for men and women were 1.31 and 1.19, (95% CI: 1.30–1.32 and 1.18–1.20), respectively. The historical disparity values for men and women were −281 and −365 kilocalorie-per-day, (95% CI: −299, −264 and −378, −351), respectively. These results are indicative of significant under-reporting. The greatest mean disparity values were −716 kcal/day and −856 kcal/day for obese (i.e., ≥30 kg/m2) men and women, respectively.
Across the 39-year history of the NHANES, EI data on the majority of respondents (67.3% of women and 58.7% of men) were not physiologically plausible. Improvements in measurement protocols after NHANES II led to small decreases in underreporting, artifactual increases in rEI, but only trivial increases in validity in subsequent surveys. The confluence of these results and other methodological limitations suggest that the ability to estimate population trends in caloric intake and generate empirically supported public policy relevant to diet-health relationships from U.S. nutritional surveillance is extremely limited.
The rise in the population prevalence of obesity has focused attention on U.S. nutritional surveillance research and the analysis of trends in caloric energy intake (EI). Because these efforts provide the scientific foundation for many public health policies and food-based guidelines, poor validity in dietary measurement protocols can have significant long-term implications for our nation’s health.
In the U.S., population-level estimates of EI are derived from data collected as part of the National Health and Nutrition Examination Survey (NHANES), a complex, cross-sectional sample of the U.S. population. The primary method used in NHANES to approximate EI is the 24-hour dietary recall interview (24HR)
Given the indirect, pseudo-quantitative nature of the method (i.e., assigning numeric values to subjective data without objective corroboration), nutrition surveys frequently report a range of energy intakes that are not representative of the respondents’ habitual intakes
Because the NHANES collected dietary data over the period in which the population prevalence of obesity was increasing, these data have been used (despite the widely acknowledged issues
Data were obtained from the National Health and Nutrition Examination Surveys for the years 1971–2010
The study sample was limited to adults aged ≥20 and
Estimates of EI were obtained from a single 24HR from each of the nine NHANES study periods
The ratio of rEI to BMR (rEI/BMR) <1.35
It is important to note that the <1.35 cut-off does not assess all forms of misreporting (e.g., over-reporting). To avoid the confounding effects of potential over-reporting, all rEI/BMR values >2.40
In 2002, the IOM used datasets derived from studies using DLW to create factorial equations to estimate energy requirements for the US population. IOM TEE values were subtracted from the NHANES rEI to calculate disparity values. Negative values indicate underreporting.
Equation 1 Men: TEE = 864– (9.72×age [y])+PA*×(14.2×weight [kg]+503×height[m]) (±202).
Equation 2 Women: TEE = 387– (7.31×age [y]+PA*×(10.8×weight [kg]+660.7×height[m]) (±156).
* Physical activity (PA) values were 1.12 and 1.14 for NW men and women, respectively. The use of these values assumes a physical activity level (PAL) of ≥1.4 and <1.6, which is indicative of a “low active” population
Equation 3 Men: TEE = 1086– (10.1×age [y])+PA*×(13.7×weight [kg]+416×height [m]).
Equation 4 Women: TEE = 448– (7.95×age [y])+PA*×(11.4×weight [kg]+619×height [m]).
*PA values were 1.12 and 1.16 for OW/OB men and women, respectively. The use of these values assumes a physical activity level (PAL) of ≥1.4 and <1.6, which is indicative of a “low active” population
Note: age (years); weight (kg); height (m; meters); BMI = body mass index, (kg/m2), IOM = Institute of Medicine; TEE = total energy expenditure.
Body mass was measured to ±0.1 kg. Height was measured to ±0.1 cm. BMI was calculated as weight (kg)/height (m)2. The sample was divided into three standard BMI categories: BMI ≥18 kg/m2 and <25 kg/m2 were normal weight (NW), BMI between 25 kg/m2 and 29.9 kg/m2 were overweight (OW), and ≥30 kg/m2 were obese (OB).
Data processing and statistical analyses were performed using SAS®, V 9.2 and SPSS® V.19 in 2012–2013. Analyses accounted for the NHANES’ complex survey design via the incorporation of stratification, clustering and post-stratification weighting to maintain a nationally representative sample for each survey period. All analyses included adjusted means, and
Reported Energy Intake (rEI)/Basal Metabolic Rate (BMR) rEI/BMR >1.35 = plausible US Men & Women (20–74 years); NHANES I - NHANES 2009–2010 | ||||||
NHANESSurvey Year | Sex | Estimate rEI/RMR (mean) |
Standard Error | 95% Confidence Interval | rEI Value Plausible Y = Yes N = No | |
Lower | Upper | |||||
NHANES I | Men (n = 4652) | 1.30 | 0.012 | 1.28 | 1.32 | N |
Women (n = 7709) | 1.10 | 0.010 | 1.08 | 1.12 | N | |
NHANES II | Men (n = 5236) | 1.28 | 0.010 | 1.26 | 1.30 | N |
Women (n = 6006) | 1.08 | 0.008 | 1.06 | 1.09 | N | |
NHANES III | Men (n = 6122) | 1.36 |
0.011 | 1.34 | 1.39 | Y |
Women (n = 7127) | 1.22 |
0.009 | 1.20 | 1.24 | N | |
NHANES I999–00 | Men (n = 1600) | 1.31 | 0.018 | 1.27 | 1.34 | N |
Women (n = 1886) | 1.23 |
0.016 | 1.19 | 1.26 | N | |
NHANES 2001–2002 | Men (n = 1782) | 1.31 | 0.015 | 1.28 | 1.34 | N |
Women (n = 2029) | 1.24 |
0.011 | 1.22 | 1.26 | N | |
NHANES 2003–2004 | Men (n = 1671) | 1.32 | 0.013 | 1.30 | 1.35 | Y |
Women (n = 1838) | 1.23 |
0.018 | 1.20 | 1.27 | N | |
NHANES 2005–2006 | Men (n = 1749) | 1.34 |
0.013 | 1.31 | 1.36 | Y |
Women (n = 1998) | 1.21 |
0.014 | 1.18 | 1.24 | N | |
NHANES 2007–08 | Men (n = 2154) | 1.27 | 0.017 | 1.24 | 1.30 | N |
Women (n = 2306) | 1.19 |
0.020 | 1.15 | 1.23 | N | |
NHANES 2009–2010 | Men (n = 2319) | 1.29 | 0.013 | 1.26 | 1.31 | N |
Women (n = 2532) | 1.20 |
0.007 | 1.18 | 1.21 | N | |
All estimates are weighted means.
Significantly different from NHANES I at p≤0.001 (Women).
Significantly different from NHANES I at p≤0.001 (Men).
Significantly different from NHANES I at p≤0.05 (Men).
Note: rEI was from NHANES 24HR data and BMR was calculated using the Schofield predictive equations.
Values <1.35 are not physiologically credible.
As
Reported Energy Intake (rEI)/Basal Metabolic Rate (BMR) rEI/BMR >1.35 = plausible US Women (20–74 years); NHANES I - NHANES 2009–2010 | ||||||
NHANESSurvey Year | BMI Category | EstimaterEI/BMR(Mean) |
Standard Error | 95% Confidence Interval | rEI Value Plausible Y = Yes N = No | |
Lower | Upper | |||||
NHANES I | Normal (n = 4222) | 1.20 | 0.013 | 1.18 | 1.23 | N |
Overweight (n = 2028) | 1.00 | 0.012 | 0.98 | 1.02 | N | |
Obese (n = 1459) | 0.88 | 0.014 | 0.86 | 0.91 | N | |
NHANES II | Normal (n = 3171) | 1.18 | 0.010 | 1.16 | 1.20 | N |
Overweight (n = 1671) | 0.98 | 0.012 | 0.96 | 1.01 | N | |
Obese (n = 1164) | 0.89 | 0.012 | 0.87 | 0.91 | N | |
NHANES III | Normal (n = 2661) | 1.32 | 0.014 | 1.30 | 1.35 | Y |
Overweight (n = 2150) | 1.18 | 0.019 | 1.14 | 1.22 | N | |
Obese (n = 2316) | 1.07 | 0.015 | 1.04 | 1.10 | N | |
NHANES 1999–2000 | Normal (n = 555) | 1.36 | 0.020 | 1.32 | 1.40 | Y |
Overweight (n = 572) | 1.19 | 0.033 | 1.12 | 1.25 | N | |
Obese (n = 759) | 1.12 | 0.030 | 1.06 | 1.18 | N | |
NHANES 2001–2002 | Normal (n = 630) | 1.38 | 0.018 | 1.35 | 1.42 | Y |
Overweight (n = 639) | 1.26 | 0.028 | 1.21 | 1.32 | N | |
Obese (n = 760) | 1.08 | 0.012 | 1.05 | 1.10 | N | |
NHANES 2003–2004 | Normal (n = 550) | 1.35 | 0.031 | 1.29 | 1.41 | Y |
Overweight (n = 546) | 1.19 | 0.027 | 1.14 | 1.25 | N | |
Obese (n = 742) | 1.15 | 0.026 | 1.10 | 1.20 | N | |
NHANES 2005–2006 | Normal (n = 615) | 1.34 | 0.026 | 1.29 | 1.39 | Y |
Overweight (n = 558) | 1.19 | 0.028 | 1.13 | 1.24 | N | |
Obese (n = 825) | 1.10 | 0.024 | 1.05 | 1.15 | N | |
NHANES 2007–2008 | Normal (n = 634) | 1.30 | 0.038 | 1.23 | 1.38 | Y |
Overweight (n = 694) | 1.17 | 0.026 | 1.12 | 1.22 | N | |
Obese (n = 978) | 1.10 | 0.020 | 1.06 | 1.14 | N | |
NHANES 2009–2010 | Normal (n = 690) | 1.31 | 0.022 | 1.26 | 1.35 | Y |
Overweight (n = 745) | 1.23 | 0.024 | 1.18 | 1.28 | N | |
Obese (n = 1097) | 1.08 | 0.006 | 1.06 | 1.09 | N |
All estimates are weighted means.
Note: rEI was from NHANES 24HR data and BMR was calculated using the Schofield predictive equations.
As
Reported Energy Intake (rEI)/Basal Metabolic Rate (BMR) rEI/BMR >1.35 = plausible US Men (20–74 years); NHANES I - NHANES 2009–2010 | ||||||
NHANESSurvey Year | BMI Category | Estimate rEI/BMR (Mean) |
Standard Error | 95% Confidence Interval | rEI Value Plausible Y = Yes N = No | |
Lower | Upper | |||||
NHANES I | Normal (n = 2115) | 1.41 | 0.016 | 1.38 | 1.44 | Y |
Overweight (n = 1945) | 1.24 | 0.017 | 1.21 | 1.28 | N | |
Obese (n = 592) | 1.08 | 0.025 | 1.04 | 1.13 | N | |
NHANES II | Normal (n = 2431) | 1.37 | 0.009 | 1.35 | 1.39 | Y |
Overweight (n = 2111) | 1.25 | 0.015 | 1.22 | 1.28 | N | |
Obese (n = 694) | 1.08 | 0.018 | 1.05 | 1.12 | N | |
NHANES III | Normal (n = 2275) | 1.47 | 0.018 | 1.43 | 1.50 | Y |
Overweight (n = 2482) | 1.35 | 0.015 | 1.32 | 1.38 | Y | |
Obese (n = 1365) | 1.20 | 0.018 | 1.17 | 1.24 | N | |
NHANES 1999–2000 | Normal (n = 476 ) | 1.42 | 0.020 | 1.38 | 1.46 | Y |
Overweight (n = 655) | 1.33 | 0.022 | 1.28 | 1.37 | Y | |
Obese (n = 469) | 1.16 | 0.036 | 1.09 | 1.23 | N | |
NHANES 2001–2002 | Normal (n = 493) | 1.43 | 0.038 | 1.35 | 1.50 | Y |
Overweight (n = 774) | 1.32 | 0.017 | 1.29 | 1.36 | Y | |
Obese (n = 515) | 1.18 | 0.027 | 1.13 | 1.24 | N | |
NHANES 2003–2004 | Normal (n = 465) | 1.46 | 0.029 | 1.41 | 1.52 | Y |
Overweight (n = 659) | 1.35 | 0.025 | 1.30 | 1.40 | Y | |
Obese (n = 547) | 1.18 | 0.035 | 1.11 | 1.24 | N | |
NHANES 2005–2006 | Normal (n = 413) | 1.51 | 0.030 | 1.45 | 1.57 | Y |
Overweight (n = 735) | 1.33 | 0.023 | 1.29 | 1.38 | Y | |
Obese (n = 601) | 1.22 | 0.014 | 1.19 | 1.25 | N | |
NHANES 2007–2008 | Normal (n = 539) | 1.40 | 0.038 | 1.32 | 1.47 | Y |
Overweight (n = 835) | 1.29 | 0.017 | 1.26 | 1.32 | N | |
Obese (n = 790) | 1.15 | 0.019 | 1.12 | 1.19 | N | |
NHANES 2009–2010 | Normal (n = 563) | 1.38 | 0.027 | 1.33 | 1.44 | Y |
Overweight (n = 872) | 1.35 | 0.021 | 1.31 | 1.39 | Y | |
Obese (n = 884) | 1.16 | 0.016 | 1.13 | 1.19 | N |
All estimates are weighted means.
Note: rEI was from NHANES 24HR data and BMR was calculated using the Schofield predictive equations.
As shown in
As
Disparity between rEI and IOM TEE US Men & Women (20–74 years) NHANES I – NHANES 2009–2010 | ||||||
NHANESSurvey Year | Sex | EstimaterEI minus TEE (mean) |
Standard Error | 95% Confidence Interval (CI) | Validity: 95% CI includes zero (Y = Yes, N = No) | |
Lower | Upper | |||||
NHANES I | Men (n = 4652) | −290.8 | 20.3 | −330.7 | −250.9 | N |
Women (n = 7709) | −479.7 | 14.5 | −508.1 | −451.3 | N | |
NHANES II | Men (n = 5236) | −323.2 | 17.8 | −358.1 | −288.3 | N |
Women (n = 6006) | −505.8 | 11.6 | −528.4 | −483.1 | N | |
NHANES III | Men (n = 6122) | −183.3 |
19.1 | −220.8 | −145.7 | N |
Women (n = 7127) | −325.3 |
13.5 | −351.7 | −298.8 | N | |
NHANES 1999–2000 | Men (n = 1600) | −285.3 | 37.7 | −359.3 | −211.4 | N |
Women (n = 1886) | −328.7 |
27.3 | −382.3 | −275.1 | N | |
NHANES 2001–2002 | Men (n = 1782) | −270.3 | 26.8 | −322.9 | −217.7 | N |
Women (n = 2029) | −306.0 |
15.5 | −336.3 | −275.6 | N | |
NHANES 2003–2004 | Men (n = 1671) | −255.6 | 24.7 | −304.0 | −207.3 | N |
Women (n = 1838) | −308.2 |
27.2 | −361.5 | −254.8 | N | |
NHANES 2005–2006 | Men (n = 1749) | −232.2 | 25.3 | −281.8 | −182.6 | N |
Women (n = 1998) | −347.5 |
20.8 | −388.4 | −306.6 | N | |
NHANES 2007–08 | Men (n = 2154) | −355.0 | 32.1 | −417.9 | −292.0 | N |
Women (n = 2306) | −379.4 |
28.5 | −435.3 | −323.5 | N | |
NHANES 2009–2010 | Men (n = 2319) | −330.9 | 22.7 | −375.4 | −286.4 | N |
Women (n = 2532) | −366.9 |
9.8 | −386.1 | −347.7 | N | |
− |
− |
− |
||||
− |
− |
− |
All estimates are weighted means.
Significantly different from NHANES I at p≤0.001 (Women).
Significantly different from NHANES I at p≤0.001 (Men).
Significantly different from NHANES I at p≤0.05 (Men).
Significantly different from NHANES I at p≤0.05 (Women).
Note: TEE = estimated total energy expenditure; IOM = Institute of Medicine; rEI = reported energy intake; BMR = Basal Metabolic Rate calculated via Schofield predictive equation.
These values were calculated by subtracting the IOM TEE from the NHANES rEI. Negative values indicate the kilocalorie-per-day (kcal/day) value of underreporting.
As
When stratified by sex and BMI categories (see
Disparity between rEI and IOM TEE; US Women by BMI categories (20–74 years) NHANES I – NHANES 2009–2010 | ||||||
NHANESSurvey Year | BMI Category | Estimate rEI minus TEE (mean) | Standard Error | 95% Confidence Interval (CI) | Validity: 95% CI includes zero (Y = Yes, N = No) | |
Lower | Upper | |||||
NHANES I | Normal n = 4222) | −316.0 | 17.7 | −350.8 | −281.2 | N |
Overweight (n = 2028) | −595.3 | 17.7 | −629.9 | −560.6 | N | |
Obese (n = 1459) | −856.0 | 23.5 | −902.0 | −809.9 | N | |
NHANES II | Normal (n = 3171) | −351.6 | 13.7 | −378.5 | −324.8 | N |
Overweight (n = 1671) | −617.6 | 17.1 | −651.1 | −584.1 | N | |
Obese (n = 1164) | −850.6 | 19.5 | −888.9 | −812.3 | N | |
NHANES III | Normal (n = 2661) | −158.6 | 17.7 | −193.3 | −123.9 | N |
Overweight (n = 2150) | −357.1 | 26.5 | −409.1 | −305.2 | N | |
Obese (n = 2316) | −594.2 | 22.6 | −638.5 | −549.9 | N | |
NHANES 1999–2000 | Normal (n = 555) | −106.0 | 27.2 | −159.3 | −52.6 | N |
Overweight (n = 572) | −359.6 | 48.8 | −455.3 | −264.0 | N | |
Obese (n = 759) | −530.1 | 50.2 | −628.5 | −431.6 | N | |
NHANES 2001–2002 | Normal (n = 630) | −74.0 | 21.7 | −116.6 | −31.4 | N |
Overweight (n = 639) | −239.6 | 38.7 | −315.5 | −163.7 | N | |
Obese (n = 760) | −591.1 | 20.5 | −631.4 | −550.9 | N | |
NHANES 2003–2004 | Normal (n = 550) | −116.3 | 39.2 | −193.2 | −39.4 | N |
Overweight (n = 546) | −339.0 | 37.7 | −413.0 | −265.0 | N | |
Obese (n = 742) | −477.1 | 42.2 | −560.0 | −394.2 | N | |
NHANES 2005–2006 | Normal (n = 615) | −131.1 | 34.1 | −198.0 | −64.3 | N |
Overweight (n = 558) | −342.8 | 38.0 | −417.4 | −268.3 | N | |
Obese (n = 825) | −567.3 | 38.7 | −643.2 | −491.3 | N | |
NHANES 2007–2008 | Normal (n = 634) | −173.2 | 52.1 | −275.4 | −71.0 | N |
Overweight (n = 694) | −374.1 | 35.8 | −444.4 | −303.7 | N | |
Obese (n = 978) | −567.3 | 33.2 | −632.5 | −502.1 | N | |
NHANES 2009–2010 | Normal (n = 690) | −173.0 | 27.8 | −227.5 | −118.4 | N |
Overweight (n = 745) | −288.9 | 34.0 | −355.7 | −222.2 | N | |
Obese (n = 1097) | −590.5 | 14.0 | −617.8 | −563.1 | N |
Note: BMI = body mass index; TEE = estimated total energy expenditure; IOM = Institute of Medicine; rEI = reported energy intake; BMR = Basal Metabolic Rate calculated via Schofield predictive equation.
These values were calculated by subtracting the IOM TEE from the NHANES rEI for each respondent. Negative values indicate the kcal/day value of underreporting.
Disparity between rEI and IOM TEE; US Men by BMI categories (20–74 years) NHANES I – NHANES 2009–2010 | ||||||
NHANESSurvey Year | BMI Category | Estimate rEI minus TEE (mean) | Standard Error | 95% Confidence Interval (CI) | Validity: 95% CI includes zero (Y = Yes, N = No) | |
Lower | Upper | |||||
NHANES I | Normal (n = 2115) | −96.3 | 26.8 | −149.0 | −43.6 | N |
Overweight (n = 1945) | −374.7 | 30.8 | −435.1 | −314.2 | N | |
Obese (n = 592) | −702.1 | 49.7 | −799.7 | −604.5 | N | |
NHANES II | Normal (n = 2431) | −178.7 | 15.9 | −209.9 | −147.6 | N |
Overweight (n = 2111) | −367.6 | 27.0 | −420.5 | −314.6 | N | |
Obese (n = 694) | −716.5 | 37.3 | −789.8 | −643.3 | N | |
NHANES III | Normal (n = 2275) | −8.8 | 31.1 | −69.8 | 52.2 | Y |
Overweight (n = 2482) | −191.5 | 27.9 | −246.3 | −136.7 | N | |
Obese (n = 1365) | −494.4 | 38.0 | −569.0 | −419.9 | N | |
NHANES 1999–2000 | Normal (n = 476 ) | −87.2 | 34.8 | −155.6 | −18.8 | N |
Overweight (n = 655) | −221.8 | 41.5 | −303.3 | −140.2 | N | |
Obese (n 469) | −590.9 | 76.8 | −741.6 | −440.2 | N | |
NHANES 2001–2002 | Normal (n = 493) | −64.1 | 63.1 | −188.0 | 59.9 | Y |
Overweight (n = 774) | −229.2 | 29.5 | −287.1 | −171.3 | N | |
Obese (n = 515) | −527.5 | 55.3 | −636.1 | −418.9 | N | |
NHANES 2003–2004 | Normal (n = 465) | −6.8 | 47.3 | −99.6 | 86.0 | Y |
Overweight (n = 659) | −175.4 | 46.9 | −267.4 | −83.4 | N | |
Obese (n = 547) | −549.8 | 72.0 | −691.1 | −408.5 | N | |
NHANES 2005–2006 | Normal (n = 413) | 70.4 | 53.0 | −33.7 | 174.5 | Y |
Overweight (n = 735) | −222.4 | 39.7 | −300.3 | −144.4 | N | |
Obese (n = 601) | −464.2 | 32.1 | −527.2 | −401.2 | N | |
NHANES 2007–2008 | Normal (n = 539) | −117.9 | 64.8 | −245.2 | 9.3 | Y |
Overweight (n = 835) | −286.7 | 31.3 | −348.1 | −225.2 | N | |
Obese (n = 790) | −608.0 | 42.2 | −690.8 | −525.2 | N | |
NHANES 2009–2010 | Normal (n = 563) | −154.4 | 43.5 | −239.8 | −69.1 | N |
Overweight (n = 872 ) | −178.9 | 42.1 | −261.5 | −96.4 | N | |
Obese (n = 884) | −590.9 | 32.9 | −655.4 | −526.4 | N |
Note: BMI = body mass index; TEE = estimated total energy expenditure; IOM = Institute of Medicine; rEI = reported energy intake; BMR = Basal Metabolic Rate calculated via Schofield predictive equation.
These values were calculated by subtracting the estimated IOM TEE from the NHANES rEI for each respondent. Negative numbers indicate the kcal/day value of underreporting.
After the removal of over-reporters, both protocols, that is rEI/BMR (
Across the study period, approximately 4.9% of men and 2.9% of women reported rEI/BMR values suggestive of over-reporting (i.e., rEI/BMR >2.4) with no significant trends. The greatest increase in the percentage of over-reporters between survey periods occurred from NHANES II to NHANES III, with men increasing from 4.1% to 6.4%, and women from 1.7% to 3.4% (both p<0.001). The greatest absolute percentage of over-reporters was in NHANES III, with 6.4% of men over-reporting and NHANES 2003–2004, with 3.9% of women over-reporting.
Our results suggest that across the 39-year history of U.S. nutrition surveillance research, rEI data on the majority of respondents (67.3% of women and 58.7% of men) were not physiologically plausible. The historical average rEI/BMR values for all men and women were 1.31 and 1.19 respectively (
Throughout the study period (i.e., 1971–2010) the disparity between rEI and TEE values were large and variable across BMI and sex categories suggesting substantial systematic biases in underreporting (
As depicted in
These changes in measurement protocols led to an apparent increase in mean rEI values that has been reported as an actual increase in population-level EI despite caveats that the “
In addition to the ubiquity of misreporting, there is strong evidence that the reporting of ‘socially undesirable’ (e.g., high fat and/or high sugar) foods has changed as the prevalence of obesity has increased
Selective misreporting of specific macronutrients has important ramifications for epidemiological research and nutrition surveillance. Heitmann and Lissner (2005) demonstrated that the selective misreporting of dietary fat by groups at an increased risk of chronic non-communicable diseases may result in an overestimated association between fat consumption and disease
In addition to known sources of systematic reporting error, there are numerous sources of systematic bias in nutrition surveillance research protocols that are not addressed via our data. Another potentially large source of error is the translation of food and beverage consumption data (e.g. 24HR) into nutrient energy values via nutrient composition databases. The accuracy of this translation relies on a number of assumptions that are rarely justified. As cited earlier, research on misreporting shows that reports do not accurately reflect the quantity or number of foods consumed, and are not representative of usual intakes
Throughout its history, the NHANES has relied upon databases of varying quality and composition for the
As with the improvements in the NHANES survey protocols, the progressive alterations to the nutrient database combined with changes in the types of foods that are available for consumption led to artifactual differences in nutrient and energy consumption estimates that frustrate efforts to examine trends in caloric consumption
One of the most prominent systematic errors from 24HR data-to-nutrient energy conversions is due to the increased reliance on the food service industry and the substantial rise in meals eaten ‘away from home’
Recent research has attempted to quantify the changes in consumer packaged foods and beverages, and their impact on the American diet
There are various methods that attempt to improve estimates of caloric consumption derived from self-reported dietary intake
A strength of the present study was the use of the established rEI/BMR method for the determination of physiologically implausible EI values. We used a liberal cutoff (i.e., <1.35) that is below the study-specific theoretical cutoff for our smallest sub-group (i.e.,
Finally, the use of the IOM factorial equations for estimating TEE for specific subgroups (i.e., OW & OB respondents) in the calculation of disparity values is a significant strength. The results of this additional protocol demonstrated significant underreporting in all surveys, and that the disparity values closely paralleled the implausible values in 15 of the 18 sub-groups (i.e., men & women in 9 surveys). The close agreement between these two dissimilar protocols increases confidence in our results and conclusions.
A potential limitation to our analysis was the use of the Schofield predictive equation for estimating BMR. The Schofield predictive equations may overestimate BMR in some populations
Throughout its history, NHANES dietary measurement protocols have failed to provide accurate estimates of the habitual caloric consumption of the U.S. population. Furthermore, successive changes to the nutrient databases used for the 24HR data-to-energy conversations and improvements in measurement protocols make it exceedingly difficult to discern temporal patterns in caloric intake that can be related to changes in population rates of obesity. As such, there are no valid population-level data to support speculations regarding trends in caloric consumption and the etiology of the obesity epidemic. Because under-reporting and physiologically implausible rEI values are a predominant feature of U.S. nutritional surveillance, the ability to generate empirically supported public policy and dietary guidelines relevant to the obesity epidemic based on these data is extremely limited.
The data used in this study are available at: