Frequency of Eating in the US Population: A Narrative Review of the 2020 Dietary Guidelines Advisory Committee Report.

Background: A person's daily nutrient intake and overall nutritional status are determined by a complex interplay of the types and amounts of foods ingested in combination with the timing and frequency of eating. Objectives: The aim was to summarize frequency of eating occasion data examined by the 2020 Dietary Guidelines Advisory Committee, the macronutrient contributions they provide, and meal frequency relative to dietary quality among the US population (≥2 y), with a focus on sex, age, race/Hispanic origin, and income. Methods: Demographic and 24-h recall data from the 2013-2016 NHANES were examined. An eating occasion was defined as "any ingestive event (e.g., solid food, beverage, water) that is either energy yielding or non-energy yielding"; all eating occasions were further divided into discrete meals and snacks. Frequency of meals and snacks was defined as "the number of daily EOs [eating occasions]," respectively. Diet quality was assessed via the Healthy Eating Index (HEI)-2015. Results: Most Americans consume 2 (28%) to 3 (64%) meals on a given day and >90% consume 2 to 3 snacks on that day. Adult, Hispanic, and non-Hispanic Black and lower-income (<131% family poverty-to-income ratio) Americans had a lower frequency of eating than children or adolescents, non-Hispanic White, and non-Hispanic Asian Americans and higher-income Americans, respectively. Americans who reported 3 meals on a given day consumed a diet higher in dietary quality than Americans who consumed 2 meals on a given day (HEI-2015: 61.0 vs. 55.0), regardless of population subgroup. Conclusions: The frequency of the types of eating occasions differs according to age, race and Hispanic origin, and income. Dietary quality is associated with the number of meals consumed. Healthy dietary patterns can be constructed in a variety of ways to suit different life stages, cultural practices, and income levels; improved diet quality and careful consideration of nutrient density when planning meals are warranted.

National Food Intake Assessment: Technologies to Advance Traditional Methods.

National dietary surveillance produces dietary intake data used for various purposes including development and evaluation of national policies in food and nutrition. Since 2000, What We Eat in America, the dietary component of the National Health and Nutrition Examination Survey, has collected dietary data and reported on the dietary intake of the US population. Continual innovations are required to improve methods of data collection, quality, and relevance. This review article evaluates the strengths and limitations of current and newer methods in national dietary data collection, underscoring the use of technology and emerging technology applications. We offer four objectives for national dietary surveillance that serve as guiding principles in the evaluation. Moving forward, national dietary surveillance must take advantage of new technologies for their potential in enhanced efficiency and objectivity in data operations while continuing to collect accurate dietary information that is standardized, validated, and publicly transparent.

Dietary and Complementary Feeding Practices of US Infants, 6 to 12 Months: A Narrative Review of the Federal Nutrition Monitoring Data.

Complementary foods and beverages (CFBs) are key components of an infant's diet in the second 6 months of life. This article summarizes nutrition and feeding practices examined by the 2020 Dietary Guidelines Advisory Committees during the CFB life stage. Breastfeeding initiation is high (84%), but exclusive breastfeeding at 6 months (26%) is below the Healthy People 2030 goal (42%). Most infants (51%) are introduced to CFBs sometime before 6 months. The primary mode of feeding (ie, human milk fed [HMF]; infant formula or mixed formula and human milk fed [FMF]) at the initiation of CFBs is associated with the timing of introduction and types of CFBs reported. FMF infants (42%) are more likely to be introduced to CFBs before 4 months compared with HMF infants (19%). Different dietary patterns, such as higher prevalence of consumption and mean amounts, were observed, including fruit, grains, dairy, proteins, and solid fats. Compared with HMF infants of the same age, FMF infants consume more total energy (845 vs 631 kcal) and protein (22 vs 12 g) from all sources, and more energy (345 vs 204 kcal) and protein (11 vs 6 g) from CFBs alone. HMF infants have a higher prevalence of risk of inadequate intakes of iron (77% vs 7%), zinc (54% vs <3%), and protein (27% vs <3%). FMF infants are more likely to have an early introduction (<12 months) to fruit juice (45% vs 20%) and cow's milk (36% vs 24%). Registered dietitian nutritionists and nutritional professionals should consider tailoring their advice to caregivers on dietary and complementary feeding practices, taking into account the primary mode of milk feeding during this life stage to support infants' nutrient adequacy. National studies that address the limitations of this analysis, including small sample sizes and imputed breast milk volume, could refine findings from this analysis.

Comparison of 4 Methods to Assess the Prevalence of Use and Estimates of Nutrient Intakes from Dietary Supplements among US Adults.

BACKGROUND: Accurate and reliable methods to assess prevalence of use of and nutrient intakes from dietary supplements (DSs) are critical for research, clinical practice, and public health monitoring. NHANES has been the primary source of DS usage patterns using an in-home inventory with a frequency-based DS and Prescription Medicine Questionnaire (DSMQ), but little is known regarding DS information obtained from 24-h dietary recalls (24HRs). METHODS: The objectives of this analysis were to compare results from 4 different methods for measuring DS use constructed from two data collection instruments (i.e., DSMQ and 24HR) and to determine the most comprehensive method for measuring the prevalence of use and estimating nutrient intakes from DS for selected nutrients. NHANES 2011-2014 data from US adults (aged ≥19 y; n = 11,451) were used to examine the 4 combinations of methods constructed for measuring the prevalence of use of and amount of selected nutrients from DSs (i.e., riboflavin, vitamin D, folate, magnesium, calcium): 1) DSMQ, 2) 24HR day 1, 3) two 24HRs (i.e., mean), and 4) DSMQ or at least one 24HR. RESULTS: Half of US adults reported DS use on the DSMQ (52%) and on two 24HRs (mean of 49%), as compared with a lower prevalence of DS use when using a single 24HR (43%) and a higher (57%) prevalence when combining the DSMQ with at least one 24HR. Mean nutrient intake estimates were highest using 24HR day 1. Mean supplemental calcium from the DSMQ or at least one 24HR was 372 mg/d, but 464 mg/d on the 24HR only. For vitamin D, the estimated intakes per consumption day were higher on the DSMQ (46 µg) and the DSMQ or at least one 24HR (44 µg) than those on the 24HR day 1 (32 µg) or the mean 24HR (31 µg). Fewer products were also classed as a default or reasonable match on the DSMQ than on the 24HR. CONCLUSIONS: A higher prevalence of use of DSs is obtained using frequency-based methods, whereas higher amounts of nutrients are reported from a 24HR. The home inventory results in greater accuracy for products reported. Collectively, these findings suggest that combining the DSMQ with at least one 24HR (i.e., DSMQ or at least one 24HR) is the most comprehensive method for assessing the prevalence of and estimating usual intake from DSs in US adults.This trial was registered at clinicaltrials.gov as NCT03400436.

Evaluation of measurement error in 24-hour dietary recall for assessing sodium and potassium intake among US adults - National Health and Nutrition Examination Survey (NHANES), 2014.

BACKGROUND: Understanding measurement error in sodium and potassium intake is essential for assessing population intake and studying associations with health outcomes. OBJECTIVE: The aim of this study was to compare sodium and potassium intake derived from 24-h dietary recall (24HDR) with intake derived from 24-h urinary excretion (24HUE). DESIGN: Data were analyzed from 776 nonpregnant, noninstitutionalized US adults aged 20-69 y who completed 1-to-2 24HUE and 24HDR measures in the 2014 NHANES. A total of 1190 urine specimens and 1414 dietary recalls were analyzed. Mean bias was estimated as mean of the differences between individual mean 24HDR and 24HUE measurements. Correlations and attenuation factors were estimated using the Kipnis joint-mixed effects model accounting for within-person day-to-day variability in sodium excretion. The attenuation factor reflects the degree to which true associations between long-term intake (estimated using 24HUEs) and a hypothetical health outcome would be approximated using a single 24HDR: values near 1 indicate close approximation and near 0 indicate bias toward null. Estimates are reported for sodium, potassium, and the sodium: potassium (Na/K) ratio. Model parameters can be used to estimate correlations/attenuation factors when multiple 24HDRs are available. RESULTS: Overall, mean bias for sodium was -452 mg (95% CI: -646, -259), for potassium -315 mg (CI: -450, -179), and for the Na/K ratio -0.04 (CI: -0.15, 0.07, NS). Using 1 24HDR, the attenuation factor for sodium was 0.16 (CI: 0.09, 0.21), for potassium 0.25 (CI:0.16, 0.36), and for the Na/K ratio 0.20 (CI: 0.10, 0.25). The correlation for sodium was 0.27 (CI: 0.16, 0.37), for potassium 0.35 (CI: 0.26, 0.55), and for the Na/K ratio 0.27 (CI: 0.13, 0.32). CONCLUSIONS: Compared with 24HUE, using 24HDR underestimates mean sodium and potassium intake but is unbiased for the Na/K ratio. Additionally, using 24HDR as a measure of exposure in observational studies attenuates the true associations of sodium and potassium intake with health outcomes.

Mineral Intake Ratios Are a Weak but Significant Factor in Blood Pressure Variability in US Adults.

Background: Hypertension contributes substantially to chronic disease and mortality. Mineral intakes can modify blood pressure. Objective: Individual minerals and their intake ratios in US adults and their association with blood pressure were examined. Methods: Regression models were used to examine the associations of sodium, potassium, and calcium intakes and their ratios from food and supplements with blood pressure in 8777 US adults without impaired renal function from the 2011-2014 NHANES. We evaluated men (n = 4395) and women (n = 4382) separately. Models for predicting blood pressure were developed using age, blood pressure medication, race, body mass index (BMI), and smoking as explanatory variables. Results: Few adults met the recommended intake ratios for sodium:potassium (1.2% and 1.5%), sodium:calcium (12.8% and 17.67%), and sodium:magnesium (13.7% and 7.3%) for men and women, respectively. Approximately half of adults (55.2% of men and 54.8% of women) met calcium:magnesium intake ratio recommendations. In our regression models, the factors that explained the largest amount of variability in blood pressure were age, blood pressure medication, race/ethnicity, BMI, and smoking status. Together, these factors explained 31% and 15% of the variability in systolic blood pressure in women and men, respectively. The sodium:potassium (men and women), sodium:magnesium (women), and sodium:calcium (men) intake ratios were positively associated with systolic blood pressure, whereas calcium intake was inversely associated with systolic blood pressure in men only. When mineral intake ratios were added individually to our regression models, they improved the percentage of variability in blood pressure explained by the model by 0.13-0.21%. Conclusions: Strategies to lower blood pressure are needed. Lower sodium:potassium intake ratios provide a small benefit for protection against hypertension in US adults.

Difference between 24-h diet recall and urine excretion for assessing population sodium and potassium intake in adults aged 18-39 y.

BACKGROUND: Limited data are available on the accuracy of 24-h dietary recalls used to monitor US sodium and potassium intakes. OBJECTIVE: We examined the difference in usual sodium and potassium intakes estimated from 24-h dietary recalls and urine collections. DESIGN: We used data from a cross-sectional study in 402 participants aged 18-39 y (∼50% African American) in the Washington, DC, metropolitan area in 2011. We estimated means and percentiles of usual intakes of daily dietary sodium (dNa) and potassium (dK) and 24-h urine excretion of sodium (uNa) and potassium (uK). We examined Spearman's correlations and differences between estimates from dietary and urine measures. Multiple linear regressions were used to evaluate the factors associated with the difference between dietary and urine measures. RESULTS: Mean differences between diet and urine estimates were higher in men [dNa - uNa (95% CI) = 936.8 (787.1, 1086.5) mg/d and dK - uK = 571.3 (448.3, 694.3) mg/d] than in women [dNa - uNa (95% CI) = 108.3 (11.1, 205.4) mg/d and dK - uK = 163.4 (85.3, 241.5 mg/d)]. Percentile distributions of diet and urine estimates for sodium and potassium differed for men. Spearman's correlations between measures were 0.16 for men and 0.25 for women for sodium and 0.39 for men and 0.29 for women for potassium. Urinary creatinine, total caloric intake, and percentages of nutrient intake from mixed dishes were independently and consistently associated with the differences between diet and urine estimates of sodium and potassium intake. For men, body mass index was also associated. Race was associated with differences in estimates of potassium intake. CONCLUSIONS: Low correlations and differences between dietary and urinary sodium or potassium may be due to measurement error in one or both estimates. Future analyses using these methods to assess sodium and potassium intake in relation to health outcomes may consider stratifying by factors associated with the differences in estimates from these methods. This trial was registered at clinicaltrials.gov as NCT01631240.

Estimating Sodium and Potassium Intakes and Their Ratio in the American Diet: Data from the 2011-2012 NHANES.

BACKGROUND: The dietary sodium-to-potassium ratio (Na:K) is shown to be more strongly associated with an increased risk of cardiovascular disease (CVD) and CVD-related mortality than either sodium or potassium intake alone. OBJECTIVE: The aim was to estimate the Na:K in the diet of US adults. METHODS: Among US adults from the 2011-2012 NHANES (≥20 y; 2393 men and 2337 women), the National Cancer Institute method was used to estimate sodium and potassium intakes, Na:K, and the percentage of individuals with Na:K <1.0 utilizing the complex, stratified, multistage probability cluster sampling design. RESULTS: Overall, women had a significantly lower Na:K than men (mean ± SE: 1.32 ± 0.02 compared with 1.45 ± 0.02). Non-Hispanic whites had a significantly lower Na:K than non-Hispanic blacks and non-Hispanic Asians (1.34 ± 0.02 compared with 1.54 ± 0.03 and 1.49 ± 0.04, respectively). Only 12.2% ± 1.5% of US adults had a Na:K < 1.0. The Na:K decreased linearly as age increased. Most adults (90% ± 0.8%) had sodium intakes >2300 mg/d, whereas <3% had potassium intakes >4700 mg/d. Grains and vegetables were among the highest contributors to sodium intakes for adults with Na:K < 1.0, compared with protein foods and grains for those with Na:K ≥ 1.0. Vegetables and milk and dairy products constituted the primary dietary sources of potassium for individuals with Na:K < 1.0, whereas mixed dishes and protein foods contributed the most potassium for individuals with ratios ≥1.0. Individuals with a Na:K < 1.0 were less likely to consume mixed dishes and condiments and were more likely to consume vegetables, milk and dairy products, and fruit than those with a Na:K ≥ 1.0. CONCLUSION: Only about one-tenth of US adults have a Na:K consistent with the WHO guidelines for reduced risk of mortality. Continued efforts to reduce sodium intake in tandem with novel strategies to increase potassium intake are warranted.

Vital signs: fruit and vegetable intake among children - United States, 2003-2010.

BACKGROUND: Eating more fruits and vegetables adds underconsumed nutrients to diets, reduces the risks for leading causes of illness and death, and helps manage body weight. This report describes trends in the contributions of fruits and vegetables to the diets of children aged 2-18 years. METHODS: CDC analyzed 1 day of 24-hour dietary recalls from the National Health and Nutrition Examination Surveys from 2003 to 2010 to estimate trends in children's fruit and vegetable intake in cup-equivalents per 1,000 calories (CEPC) and trends by sex, age, race/ethnicity, family income to poverty ratio, and obesity status. Total fruit includes whole fruit (all fruit excluding juice) and fruit juice (from 100% juice, foods, and other beverages). Total vegetables include those encouraged in the Dietary Guidelines for Americans, 2010 (i.e., dark green, orange, and red vegetables and legumes), white potatoes, and all other vegetables. RESULTS: Total fruit intake among children increased from 0.55 CEPC in 2003-2004 to 0.62 in 2009-2010 because of significant increases in whole fruit intake (0.24 to 0.40 CEPC). Over this period, fruit juice intake significantly decreased (0.31 to 0.22 CEPC). Total vegetable intake did not change (0.54 to 0.53 CEPC). No socio-demographic group met the Healthy People 2020 target of 1.1 CEPC vegetables, and only children aged 2-5 years met the target of 0.9 CEPC fruits. CONCLUSIONS: Children's total fruit intake increased because of increases in whole fruit consumption, but total vegetable intake remained unchanged. IMPLICATIONS FOR PUBLIC HEALTH PRACTICE: Increased attention to the policies and food environments in multiple settings, including schools, early care and education, and homes might help continue the progress in fruit intake and improve vegetable intake.

Difference in adult food group intake by sex and age groups comparing Brazil and United States nationwide surveys.

BACKGROUND: International comparisons of dietary intake are an important source of information to better understand food habits and their relationship to nutrition related diseases. The objective of this study is to compare food intake of Brazilian adults with American adults identifying possible dietary factors associated with the increase in obesity in Brazil. METHODS: This research used cross-national analyses between the United States and Brazil, including 5,420 adults in the 2007-2008 What We Eat In America, National Health and Nutrition Examination Survey and 26,390 adults in the 2008-2009 Brazilian Household Budget Survey, Individual Food Intake. Dietary data were collected through 24 h recalls in the U.S. and through food records in Brazil. Foods and beverages were combined into 25 food categories. Food intake means and percentage of energy contribution by food categories to the population's total energy intake were compared between the countries. RESULTS: Higher frequencies of intake were reported in the United States compared to Brazil for the majority of food categories except for meat, rice and rice dishes; beans and legumes; spreads; and coffee and tea. In either country, young adults (20-39 yrs) had greater reports of meat, poultry and fish mixed dishes; pizza and pasta; and soft drinks compared to older adults (60 + yrs). Meat, poultry and fish mixed dishes (13%), breads (11%), sweets and confections (8%), pizza and pasta (7%), and dairy products (6%) were the top five food category sources of energy intake among American adults. The top five food categories in Brazil were rice and rice dishes (13%), meat (11%), beans and legumes (10%), breads (10%), and coffee and tea (6%). Thus, traditional plant-based foods such as rice and beans were important contributors in the Brazilian diet. CONCLUSION: Although young adults had higher reports of high-calorie and nutrient-poor foods than older adults in both countries, Brazilian young adults did not consume a diet similar to Americans, indicating that it is still possible to reverse the current trends of incorporating Western dietary habits in Brazil.

Assessing U.S. sodium intake through dietary data and urine biomarkers.

Sodium intake is related to blood pressure, an established risk factor for heart disease and stroke. Reducing intake may save billions in United States health care dollars annually. Efforts targeting sodium reductions make accurate monitoring vital, yet limited information exists on the accuracy of the current data to assess sodium intake in the United States population. In this symposium, new findings were presented on the accuracy of estimating population 24-h urinary excretion of sodium from spot urine specimens or sodium intake from 24-h dietary recalls. Differences in accuracy by sex, BMI, and race were apparent as well as by timing of spot urine collections. Although some published equations appear promising for estimating group means, others are biased. Individual estimates of sodium intake were highly variable and adjustment for within-individual variation in intake is required for estimating population prevalence or percentiles. Estimates indicated United States sodium intake remains high.

The USDA Automated Multiple-Pass Method accurately assesses population sodium intakes.

BACKGROUND: Given current sodium-reduction strategies, accurate and practical methods to monitor sodium intake in the US population are critical. Although the gold standard for estimating sodium intake is the 24-h urine collection, few studies have used this biomarker to evaluate the accuracy of a dietary instrument. OBJECTIVE: Our objective was to compare self-reported dietary intake of sodium with 24-h urinary excretion obtained in the USDA Automated Multiple-Pass Method (AMPM) Validation Study. DESIGN: Subjects were healthy, weight-stable volunteers aged 30-69 y recruited from the Washington, DC, area. Data from 465 subjects who completed at least one 24-h recall and collected a complete 24-h urine sample during the same period were used to assess the validity of sodium intake. Reporting accuracy was calculated as the ratio of reported sodium intake to that estimated from the urinary biomarker (24-h urinary sodium/0.86). Estimations of sodium intake included salt added in cooking but did not include salt added at the table. RESULTS: Overall, the mean (95% CI) reporting accuracy was 0.93 (0.89, 0.97) for men (n = 232) and 0.90 (0.87, 0.94) for women (n = 233). Reporting accuracy was highest for subjects classified as normal weight [body mass index (in kg/m(2)) <25]: 1.06 (1.00, 1.12) for men (n = 84) and 0.99 (0.94, 1.04) for women (n = 115). For women only, reporting accuracy was higher in those aged 50-69 y than in those who were younger. CONCLUSION: Findings from this study suggest that the USDA AMPM is a valid measure for estimating sodium intake in adults at the population or group level.

The US Department of Agriculture Automated Multiple-Pass Method reduces bias in the collection of energy intakes.

BACKGROUND: The US Department of Agriculture Automated Multiple-Pass Method (AMPM) is used for collecting 24-h dietary recalls in What We Eat In America, the dietary interview component of the National Health and Nutrition Examination Survey. Because the data have important program and policy applications, it is essential that the validity of the method be tested. OBJECTIVE: The accuracy of the AMPM was evaluated by comparing reported energy intake (EI) with total energy expenditure (TEE) by using the doubly labeled water (DLW) technique. DESIGN: The 524 volunteers, aged 30-69 y, included an equal number of men and women recruited from the Washington, DC, area. Each subject was dosed with DLW on the first day of the 2-wk study period; three 24-h recalls were collected during the 2-wk period by using the AMPM. The first recall was conducted in person, and subsequent recalls were over the telephone. RESULTS: Overall, the subjects underreported EI by 11% compared with TEE. Normal-weight subjects [body mass index (in kg/m(2)) < 25] underreported EI by <3%. By using a linear mixed model, 95% CIs were determined for the ratio of EI to TEE. Approximately 78% of men and 74% of women were classified as acceptable energy reporters (within 95% CI of EI:TEE). Both the percentage by which energy was underreported and the percentage of subjects classified as low energy reporters (<95% CI of EI:TEE) were highest for subjects classified as obese (body mass index > 30). CONCLUSIONS: Although the AMPM accurately reported EIs in normal-weight subjects, research is warranted to enhance its accuracy in overweight and obese persons.

Validation of a food frequency questionnaire by direct measurement of habitual ad libitum food intake.

Food frequency questionnaires are commonly used to assess habitual food intake. Although food frequency questionnaires are known to produce measurement error, the amount of error and effectiveness of correction methods are poorly understood. Twelve men from the Baltimore, MD/Washington, DC, area consumed an ad libitum diet for 16 weeks during the spring of 2001. At the end of the study period, subjects reported their food intakes with a food frequency questionnaire (Block 98). During weeks 8 and 16, subjects were dosed with doubly labeled water and maintained physical activity logs. Absolute and relative macronutrient intakes were poorly predicted by the food frequency questionnaire. The application of a single, group mean energy adjustment (using doubly labeled water or physical activity) reduced the variance of carbohydrate intake and increased the variance of fat and protein intakes, but none significantly (p>0.05). Subject-specific energy adjustments reduced the variance for carbohydrate and protein intakes (p<0.05). Including a body weight adjustment reduced the variance in fat intake (p<0.05) when doubly labeled water was used to first correct energy intake. The application of correction methods based on energy expenditure and body weight can be used to reduce measurement error, improving the ability of the food frequency questionnaire to measure food intake.

Preprandial ghrelin is not affected by macronutrient intake, energy intake or energy expenditure.

BACKGROUND: Ghrelin, a peptide secreted by endocrine cells in the gastrointestinal tract, is a hormone purported to have a significant effect on food intake and energy balance in humans. The influence of factors related to energy balance on ghrelin, such as daily energy expenditure, energy intake, and macronutrient intake, have not been reported. Secondly, the effect of ghrelin on food intake has not been quantified under free-living conditions over a prolonged period of time. To investigate these effects, 12 men were provided with an ad libitum cafeteria-style diet for 16 weeks. The macronutrient composition of the diets were covertly modified with drinks containing 2.1 MJ of predominantly carbohydrate (Hi-CHO), protein (Hi-PRO), or fat (Hi-FAT). Total energy expenditure was measured for seven days on two separate occasions (doubly labeled water and physical activity logs). RESULTS: Preprandial ghrelin concentrations were not affected by macronutrient intake, energy expenditure or energy intake (all P > 0.05). In turn, daily energy intake was significantly influenced by energy expenditure, but not ghrelin. CONCLUSION: Preprandial ghrelin does not appear to be influenced by macronutrient composition, energy intake, or energy expenditure. Similarly, ghrelin does not appear to affect acute or chronic energy intake under free-living conditions.

Commercial portion-controlled foods in research studies: how accurate are label weights?

OBJECTIVE: The purpose of this study was to evaluate the reliability of label weights as surrogates for actual weights in commercial portion-controlled foods used in a research setting. DESIGN: Actual weights of replicate samples of 82 portion-controlled food items and 17 discrete units of food from larger packaging were determined over time. Comparison was made to the package label weights for the portion-controlled food items and the per-serving weights for the discrete units. SETTING: The study was conducted at the US Department of Agriculture's Beltsville Human Nutrition Research Center's Human Study Facility, which houses a metabolic kitchen and human nutrition research facility. MAIN OUTCOME MEASURES: The primary outcome measures were the actual and label weights of 99 food items consumed by human volunteers during controlled feeding studies. Statistical analyses performed The difference between label and actual weights was tested by the paired t test for those data that complied with the assumptions of normality. The Wilcoxon signed rank test was used for the remainder of the data. Compliance with federal guidelines for packaged weights was also assessed. RESULTS: There was no statistical difference between actual and label weights for only 37 food items. The actual weights of 15 portion-controlled food items were 1% or more less than label weights, making them potentially out of compliance with federal guidelines. CONCLUSIONS: With advance planning and continuous monitoring, well-controlled feeding studies could incorporate portion-controlled food items and discrete units, especially beverages and confectionery products. Dietetics professionals should encourage individuals with diabetes and others on strict dietary regimens to check actual weights of portion-controlled products carefully against package weights.