A systematic review of the determinants of seafood consumption.

Although seafood is considered to be an important part of a balanced diet, many national food consumption surveys suggest that seafood is not consumed in sufficient amounts. As consumers are moving to diversify their diet from animal-based protein, it is important to understand the factors influencing consumption of marine foods. This review aims to assess the characteristics of seafood consumers as well as the influences on seafood consumption in Europe, USA, Canada, Australia and New Zealand. Systematic search strategies were used to identify relevant journal articles from three electronic databases (PubMed, Web of Science and Embase). Three searches were carried out and identified 4405 unique publications from which 121 met the criteria for the review process. The reviewed studies revealed that seafood consumers were more likely to be older, more affluent and more physically active and were less likely to smoke compared with non-seafood consumers. Sex and BMI did not appear to have a directional association with seafood consumption. The most commonly reported barriers to seafood consumption were cost, followed by sensory or physical barriers, health and nutritional beliefs, habits, availability and cooking skills. The most commonly reported influences were beliefs about the contribution of seafood to health, environmental influences and personal preferences. Based on the findings of this review, future intervention strategies to increase seafood consumption may need to consider affordability and education in terms of health, nutrition and cooking skills. More research is needed to explore the effectiveness of specific interventions at increasing the consumption of seafood.

Folic acid levels in some food staples in Ireland are on the decline: implications for passive folic acid intakes?

BACKGROUND: Neural tube defects are largely preventable by the maternal periconceptual consumption of folic acid. The aim of this study was to examine the levels of synthetic folic acid in foods and the range of food stuffs with added folic acid available to consumers in Ireland at the current time. METHODS: Three audits of fortified foods available in supermarkets in the Republic of Ireland were conducted. Researchers visited supermarkets and obtained folic acid levels from nutrition labels in 2004, 2008 and 2013/4. Levels were compared using MS Excel. RESULTS: The profile of foods fortified with folic acid in 2013/4 has changed since 2004. The percentage of foods fortified with folic acid has decreased as has the level of added folic acid in some food staples, such as fat/dairy spreads. CONCLUSION: Bread, milk and spreads no longer contain as much folic acid as previously (2004 and 2008). This may contribute to a decrease in folate intake and therefore may contribute to an increase in NTD rates. Research on current blood concentrations of folate status markers is now warranted.

Quantifying consumer portion control practices. A cross-sectional study.

The use of portion control practices has rarely been quantified. The present study aimed to: (1) explore which portion control practices are actually used by the general population and their association with cognitive restraint, demographic background and general health interest (GHI), and (2) examine how the usage of portion control practices predicts the estimated consumption of an energy dense food (i.e. pizza). Twenty-two portion control practices were rated in terms of their frequency of use from 'never' to 'very often' by a representative sample of 1012 consumers from the island of Ireland. Three factors were extracted and named: measurement-strategy scale, eating-strategy scale, and purchasing-strategy scale. The eating-strategy scale score was the highest, while the measurement-strategy scale carried the lowest frequency score. For each strategy scale score, the strongest predictor was GHI, followed by gender. Having higher GHI and being female were independently associated with more frequent portion control. Both the eating-strategy scale score and the purchasing-strategy scale score were negatively associated with pizza portion size consumption estimates. In conclusion, while this study demonstrates that the reported use of portion control practices is low, the findings provide preliminary evidence for their validity. Further studies are needed to explore how portion control practices are used in different kinds of portion size decisions and what their contribution is to the intake of food over an extended period of time.

Dietary isoflavone intake is associated with evoked responses to inflammatory cardiometabolic stimuli and improved glucose homeostasis in healthy volunteers.

BACKGROUND AND AIMS: Consumption of foods that modulate inflammatory stress in genetically-prone individuals may influence development of cardiometabolic diseases. Isoflavones in soy-derived foods function as phytoestrogens, have antioxidant and anti-inflammatory activity, inhibit protein-tyrosine kinase activity, and may be atheroprotective. We examined the relationship between soy food consumption and inflammatory responses to endotoxemia, postprandial responses to oral lipid tolerance test (OLTT), and insulin sensitivity from frequently sampled intravenous tolerance tests (FSIGTT). METHODS AND RESULTS: We administered low-dose endotoxin (LPS 1 ng/kg) to induce transient endotoxemia in young, healthy volunteers (N = 215) of African (AA), and European (EA) ancestry as part of the GENE Study. We further supported these findings in two independent samples: the MECHE Study and NHANES. Soy food consumption was a significant predictor of peak cytokine response following LPS. Individuals with moderate-high (>1.48 mg/day, N = 65) vs. low-no (<1.48 mg/day, N = 150) isoflavone consumption had significantly higher tumor necrosis factor alpha (TNFα) post-LPS (AUC, P = 0.009). Further, high-isoflavone consumers were protected against inflammation-induced decline in insulin sensitivity (SI) in GENE. We observed significant differences by soy consumption in the interferon gamma (IFNγ) response to OLTT, and the insulin response to OGTT in MECHE, as well as significantly lower fasting insulin, and 2-hour glucose post-OGTT in EA NHANES subjects. CONCLUSION: We demonstrate that soy consumption may influence inflammatory and metabolic responses. In research of nutritional exposures, measuring evoked phenotypes may be more informative than describing resting characteristics. The GENE Study was registered under NCT00953667 and the MECHE Study under NCT01172951, both at clinicaltrials.gov.

Pregnant immigrant Nigerian women: an exploration of dietary intakes.

OBJECTIVE: The aim of the study is to explore the dietary intakes of a prominent ethnic minority group of women from Sub-Saharan Africa during pregnancy, in order to identify nutritional issues of concern which may impact on pregnancy outcomes and whether different food based dietary guidelines may be required to meet their needs. STUDY DESIGN: This is an observational study with quantitative assessment of nutrient intakes and an exploration of meal composition and food choices. METHODS: Fifty-two Nigerian pregnant women in their second or third trimester of pregnancy were recruited from antenatal clinics in the National Maternity Hospital, Dublin, Ireland. Early pregnancy weight was measured and body mass index recorded. A 24 h dietary recall was used to assess food and nutrient intakes. RESULTS: Eighty-nine per cent of the study population were classified as overweight or obese. These women appear to be maintaining traditional African dietary habits and have a healthy macronutrient composition in the diet. The intake of key pregnancy micronutrients such as calcium, vitamin D and folate may be insufficient from diet alone to meet requirements and supplements may be inadequately utilized in a timely manner. CONCLUSIONS: These women represent a vulnerable obstetric group that may be at risk of adverse pregnancy outcomes due to high obesity rates and inadequate micronutrient status in early pregnancy. Provision of dietary advice should be tailored to suit their cultural dietary practices and food preferences. Pre-conception counselling on healthy lifestyle and appropriate supplement usage may be beneficial, although larger studies are required to assess the need for specific nutrition policy recommendations.

Comparison of Meal Patterns Across Common Racial Groups in the UK and the USA, Examining Associations with Weight Status and Diet Quality: a Secondary Analysis of NDNS and NHANES Datasets.

OBJECTIVE: Understanding diets of population subgroups is essential for monitoring health of diversifying populations, but currently, meal patterns of many population subgroups are not widely known. This paper aimed to identify meal patterns of racial groups in the UK and USA, considering if racial groups exhibit similar patterns of intake irrespective of location and relationships between meal patterns and health parameters. DESIGN: Data were extracted from the UK (National Diet and Nutrition Survey) and the USA (National Health and Nutrition Examination Survey) national dietary surveys. Temporal and content meal patterns among racial groups in the UK and USA (White, Black, Asian and Other, n = 1780 and n = 4339, respectively) were examined. Kruskal-Wallis tests were applied to understand differences across groups. Logistic regression models identified associations between meal patterns and body mass index and diet quality. RESULTS: Black groups consumed fewer eating occasions than White and Other groups in both countries, while UK racial groups consumed significantly more snacks than USA groups. Food group contribution to eating occasion consumption was similar across countries where Asian groups in the USA and UK had the lowest meat intake at lunch and dinner. Meal frequency was positively associated with diet quality. CONCLUSIONS: Overall, meal patterns differ across racial groups within a single country, and some differences were observed within groups of the same race across countries. Learnings from this research highlight the differences in consumption patterns across racial groups and the importance of considering a meal-based approach to dietary guidelines by racial group.

Maternal nutrition among women from Sub-Saharan Africa, with a focus on Nigeria, and potential implications for pregnancy outcomes among immigrant populations in developed countries.

Pregnant women in countries of Sub-Saharan Africa (SSA) are at risk of poor nutritional status and adverse outcomes as a result of poverty, food insecurity, sub-optimal healthcare facilities, frequent infections and frequent pregnancies. Studies from Nigeria, for example, have revealed a high prevalence of both under- and over-nutrition, as well as nutrient deficiencies, including iron, folate, vitamin D and vitamin A. Subsequently, obstetric complications, including hypertension, anaemia, neural tube defects, night-blindness, low birth weight and maternal and perinatal mortality, are common. Migration patterns from SSA to the Western world are on the rise in recent years, with Nigerians now representing the most prevalent immigrant African population in many developed countries. However, the effect of immigration, if any, on the nutritional status and pregnancy outcomes of these women in their host countries has not yet been studied. Consequently, it is unknown to what extent the nutritional deficiencies and pregnancy complications occurring in Nigeria, and other countries of SSA, present in these women post-emigration. This may result in missed opportunities for appropriate antenatal care of a potential high-risk group in pregnancy. The present review discusses the literature regarding nutrition in pregnancy among SSA women, using Nigeria as an example, the common nutrition-related complications that arise and the subsequent obstetric outcomes. The concept of dietary acculturation among immigrant groups is also discussed and deficiencies in the literature regarding studies on the diets of pregnant immigrant women are highlighted.

Genetic and environmental influences on serum oxylipins, endocannabinoids, bile acids and steroids.

Lipid bioactivity is a result of direct action and the action of lipid mediators including oxylipins, endocannabinoids, bile acids and steroids. Understanding the factors contributing to biological variation in lipid mediators may inform future approaches to understand and treat complex metabolic diseases. This research aims to determine the contribution of genetic and environmental influences on lipid mediators involved in the regulation of inflammation and energy metabolism. This study recruited 138 monozygotic (MZ) and dizygotic (DZ) twins aged 18-65 years and measured serum oxylipins, endocannabinoids, bile acids and steroids using liquid chromatography mass-spectrometry (LC-MS). In this classic twin design, the similarities and differences between MZ and DZ twins are modelled to estimate the contribution of genetic and environmental influences to variation in lipid mediators. Heritable lipid mediators included the 12-lipoxygenase products 12-hydroxyeicosatetraenoic acid [0.70 (95% CI: 0.12,0.82)], 12-hydroxyeicosatetraenoic acid [0.73 (95% CI: 0.30,0.83)] and 14­hydroxy-docosahexaenoic acid [0.51 (95% CI: 0.07,0.71)], along with the endocannabinoid docosahexaenoy-lethanolamide [0.52 (95% CI: 0.15,0.72)]. For others such as 13-hydroxyoctadecatrienoic acid and lithocholic acid the contribution of environment to variation was stronger. With increased understanding of lipid mediator functions in health, it is important to understand the factors contributing to their variance. This study provides a comprehensive analysis of lipid mediators and extends pre-existing knowledge of the genetic and environmental influences on the human lipidome.

Use of the cellular model of body composition to describe changes in body water compartments after total fasting, very low calorie diet and low calorie diet in obese men.

INTRODUCTION: The cellular model of body composition divides the body in body cell mass (BCM), extracellular solids and extracellular fluids. This model has been infrequently applied for the evaluation of weight loss (WL) programmes. OBJECTIVES: (1) To assess changes in body compartments in obese men undergoing fasting, very low calorie diet (VLCD) and low calorie diet (LCD); (2) to evaluate two cellular models for the determination of changes in BCM, fat mass (FM) and body fluids. MATERIALS AND METHODS: Three groups of six, obese men participated in a total fast (F) for 6 days, a VLCD (2.5 MJ per day) for 3 weeks or an LCD (5.2 MJ per day) for 6 weeks. Body composition was measured at baseline and after small ( approximately 5%) and moderate ( approximately 10%) WL. FM was measured using a four-compartment model. Total body water (TBW) and extracellular water (ECW) were, respectively, measured by deuterium and sodium bromide dilution and intracellular water (ICW) calculated by difference. Two cellular models were used to measure BCM, FM and body fluids distribution. RESULTS: After about 5%WL changes in TBW were F=-3.2+/-1.2 kg (P<0.01), VLCD=-1.2+/-0.6 kg (P<0.01), LCD=-0.3+/-0.9 kg(n.s.). The contribution of TBW to total body mass loss was indirectly associated with FM loss. ECW increased during fasting (+1.5+/-3.1 kg, n.s.), decreased during the VLCD (-2.0+/-1.5 kg, P<0.05) and remained unchanged at the end of the LCD (-0.3+/-1.6 kg, n.s.). ICW significantly decreased during fasting (-4.7+/-3.9 kg, P<0.05) but did not change in the LCD and VLCD groups. The loss of BCM was more significant in the fasting group and it was directly associated with changes in ICW. CONCLUSIONS: After a 6-day period of fasting we observed more ICW losses and less fat mobilization compared with VLCD and LCD. The cellular model of body composition is suitable for the characterization of changes in body fluids distribution during WL.

Epigenetics and gene expression.

Transcription, translation and subsequent protein modification represent the transfer of genetic information from the archival copy of DNA to the short-lived messenger RNA, usually with subsequent production of protein. Although all cells in an organism contain essentially the same DNA, cell types and functions differ because of qualitative and quantitative differences in their gene expression. Thus, control of gene expression is at the heart of differentiation and development. Epigenetic processes, including DNA methylation, histone modification and various RNA-mediated processes, are thought to influence gene expression chiefly at the level of transcription; however, other steps in the process (for example, translation) may also be regulated epigenetically. The following paper will outline the role epigenetics is believed to have in influencing gene expression.

Patterns of dairy food intake, body composition and markers of metabolic health in Ireland: results from the National Adult Nutrition Survey.

BACKGROUND: Studies examining the association between dairy consumption and metabolic health have shown mixed results. This may be due, in part, to the use of different definitions of dairy, and to single types of dairy foods examined in isolation. OBJECTIVE: The objective of the study was to examine associations between dairy food intake and metabolic health, identify patterns of dairy food consumption and determine whether dairy dietary patterns are associated with outcomes of metabolic health, in a cross-sectional survey. DESIGN: A 4-day food diary was used to assess food and beverage consumption, including dairy (defined as milk, cheese, yogurt, cream and butter) in free-living, healthy Irish adults aged 18-90 years (n=1500). Fasting blood samples (n=897) were collected, and anthropometric measurements taken. Differences in metabolic health markers across patterns and tertiles of dairy consumption were tested via analysis of covariance. Patterns of dairy food consumption, of different fat contents, were identified using cluster analysis. RESULTS: Higher (total) dairy was associated with lower body mass index, %body fat, waist circumference and waist-to-hip ratio (P<0.001), and lower systolic (P=0.02) and diastolic (P<0.001) blood pressure. Similar trends were observed when milk and yogurt intakes were considered separately. Higher cheese consumption was associated with higher C-peptide (P<0.001). Dietary pattern analysis identified three patterns (clusters) of dairy consumption; 'Whole milk', 'Reduced fat milks and yogurt' and 'Butter and cream'. The 'Reduced fat milks and yogurt' cluster had the highest scores on a Healthy Eating Index, and lower-fat and saturated fat intakes, but greater triglyceride levels (P=0.028) and total cholesterol (P=0.015). CONCLUSION: Overall, these results suggest that while milk and yogurt consumption is associated with a favourable body phenotype, the blood lipid profiles are less favourable when eaten as part of a low-fat high-carbohydrate dietary pattern. More research is needed to better understand this association. CONCLUSION: Overall, these results suggest that although milk and yogurt consumption is associated with a favourable body phenotype, the blood lipid profiles are less favourable when eaten as part of a low-fat high-carbohydrate dietary pattern. More research is needed to better understand this association.

Comparison of the portion size and frequency of consumption of 156 foods across seven European countries: insights from the Food4ME study.

There are no standardised serving/portion sizes defined for foods consumed in the European Union (EU). Typical serving sizes can deviate significantly from the 100 g/100 ml labelling specification required by the EU legislation. Where the nutritional value of a portion is specified, the portion size is determined by the manufacturers. Our objective was to investigate the potential for standardising portion sizes for specific foods, thereby ensuring complementarity across countries. We compared portion size for 156 food items measured using a food frequency questionnaire across the seven countries participating in the Food4me study. The probability of consuming a food and the frequency of consumption differed across countries for 93% and 58% of the foods, respectively. However, the individual country mean portion size differed from the average across countries in only 16% of comparisons. Thus, although dietary choices vary markedly across countries, there is much less variation in portion sizes. Our results highlight the potential for standardisation of portion sizes on nutrition labels in the EU.

Associations between FTO genotype and total energy and macronutrient intake in adults: a systematic review and meta-analysis.

Risk variants of fat mass and obesity-associated (FTO) gene have been associated with increased obesity. However, the evidence for associations between FTO genotype and macronutrient intake has not been reviewed systematically. Our aim was to evaluate the potential associations between FTO genotype and intakes of total energy, fat, carbohydrate and protein. We undertook a systematic literature search in OVID MEDLINE, Scopus, EMBASE and Cochrane of associations between macronutrient intake and FTO genotype in adults. Beta coefficients and confidence intervals (CIs) were used for per allele comparisons. Random-effect models assessed the pooled effect sizes. We identified 56 eligible studies reporting on 213,173 adults. For each copy of the FTO risk allele, individuals reported 6.46 kcal day(-1) (95% CI: 10.76, 2.16) lower total energy intake (P = 0.003). Total fat (P = 0.028) and protein (P = 0.006), but not carbohydrate intakes, were higher in those carrying the FTO risk allele. After adjustment for body weight, total energy intakes remained significantly lower in individuals with the FTO risk genotype (P = 0.028). The FTO risk allele is associated with a lower reported total energy intake and with altered patterns of macronutrient intake. Although significant, these differences are small and further research is needed to determine whether the associations are independent of dietary misreporting.

Technology-supported dietary and lifestyle interventions in healthy pregnant women: a systematic review.

Overweight and obesity are associated with increased risk of adverse maternal and fetal outcomes. However, the actuality of delivering effective lifestyle interventions in clinical practice is hampered by a high demand for resources. The use of technology to assist lifestyle interventions needs to be explored as a valid method of reducing strain on resources, and enhancing the effectiveness and population reach of interventions. The aim was to systematically review the literature on the use of technology-supported lifestyle interventions for healthy pregnant women and their impact on maternal outcomes. Online databases and registries were searched in March 2013. Primary outcomes of selected English language studies were fasting maternal glucose, incidence of gestational diabetes mellitus (GDM) and maternal gestational weight gain. Secondary outcomes were intervention uptake and acceptance, and dietary or physical activity modification. Studies whose subjects were diagnosed with GDM prior to intervention were excluded. The minimal number of eligible studies and varying outcomes precluded formal meta-analysis of the data. Initially, 203 articles were identified and screened. Seven articles, including five randomised controlled trials, met inclusion criteria for the current review. Results demonstrate several potential benefits associated with technology-supported interventions in pregnancy, despite minimal search results. Although communication technology holds potential as a safe therapeutic tool for the support of lifestyle interventions in pregnancy, there is a paucity of data on its effectiveness. Further RCTs examining the effectiveness of communication technology are required, particularly among those most likely to benefit from lifestyle interventions, such as overweight and obese pregnant women.

Habitual dietary intake impacts on the lipidomic profile.

Reliable dietary assessments are essential when attempting to understand the complex links between diet and health. Traditional methods for collecting dietary exposure can be unreliable, therefore there is an increasing interest in identifying biomarkers to provide a more accurate measurement. Metabolomics is a technology that offers great promise in this area. The aim of this study was to use a multivariate statistical strategy to link lipidomic patterns with dietary data in an attempt to identify dietary biomarkers. We assessed the relationship between lipidomic profiles and dietary data in volunteers (n=34) from the Metabolic Challenge Study (MECHE). Principal component analysis (PCA), linear regression and receiver operating characteristic (ROC) analysis were used to (1) reduce the lipidomic data into lipid patterns (LPs), (2) investigate relationships between these patterns and dietary data and (3) identify biomarkers of dietary intake. Our study identified a total of 6 novel LPs. LP1 was highly predictive of dietary fat intake (area under the curve AUC=0.82). A random forest (RF) classification model used to discriminate between low and high consumers resulted with an error rate of >10%, with a panel of six metabolites identified as the most predictive. LP4 was highly predictive of alcohol intake (AUC=0.81) with lysophosphatidylcholine alkyl C18:0 (LPCeC18:0) identified as a potential biomarker of alcohol consumption. LP6 had a reasonably good ability to predict dietary fish intake (AUC=0.76), with lysophosphatidylethanolamine acyl C18:2 (LPEaC18:2) phoshatidylethanolamine diaclyl C38:4 (PEaaC38:4) identified as potential biomarkers. The identification of these LPs and specific biomarkers will help in better classifying a persons dietary intake and in turn will improve the assessment of the relationship between diet and disease. Linking these LPs and specific biomarkers with health parameters will be an important future step.

Genetic variation in taste perception: does it have a role in healthy eating?

Taste is often cited as the factor of greatest significance in food choice, and has been described as the body's 'nutritional gatekeeper'. Variation in taste receptor genes can give rise to differential perception of sweet, umami and bitter tastes, whereas less is known about the genetics of sour and salty taste. Over twenty-five bitter taste receptor genes exist, of which TAS2R38 is one of the most studied. This gene is broadly tuned to the perception of the bitter-tasting thiourea compounds, which are found in brassica vegetables and other foods with purported health benefits, such as green tea and soya. Variations in this gene contribute to three thiourea taster groups of people: supertasters, medium tasters and nontasters. Differences in taster status have been linked to body weight, alcoholism, preferences for sugar and fat levels in food and fruit and vegetable preferences. However, genetic predispositions to food preferences may be outweighed by environmental influences, and few studies have examined both. The Tastebuddies study aimed at taking a holistic approach, examining both genetic and environmental factors in children and adults. Taster status, age and gender were the most significant influences in food preferences, whereas genotype was less important. Taster perception was associated with BMI in women; nontasters had a higher mean BMI than medium tasters or supertasters. Nutrient intakes were influenced by both phenotype and genotype for the whole group, and in women, the AVI variation of the TAS2R38 gene was associated with a nutrient intake pattern indicative of healthy eating.

Energy expenditure in disease: time to revisit?

Knowledge of energy expenditure is especially important in disease, and may in fact help in the understanding of the pathophysiology of wasting associated with disease. Energy requirements in a clinical setting are often 'prescribed' by health professionals, either directly through enteral or parenteral feeding, or perhaps controlled through a hospital diet. Studies initially suggested an increase in energy expenditure, and thus energy requirements, as a direct result of an increase in basal metabolic rate often seen in disease. However, many problems exist in the measurement of BMR in a disease situation, due to the effects of drugs, clinical practice, feeding or possibly anxiety either as a cause of the disease or the measurement itself. These problems could in themselves contribute to the rise in metabolism seen in disease. More recently, however, with the use of tracer techniques such as doubly-labelled water and the bicarbonate-urea method, more accurate estimates of energy expenditure, and thus energy requirements, have been made. Some such measurements have in fact shown that even with an elevated BMR, free-living total energy expenditure can in fact be reduced in many disease situations, suggesting a reduced rather than an increased energy requirement. The present review investigates measurements of total energy expenditure in disease to explore the hypothesis that energy expenditure in disease, even with an elevated BMR, can in fact be reduced due to a concurrent reduction in physical activity.

Measurement of total energy expenditure in grossly obese women: comparison of the bicarbonate-urea method with whole-body calorimetry and free-living doubly labelled water.

OBJECTIVE: To establish validity of the bicarbonate-urea (BU) method against direct measurements of gaseous exchange (GE) in a whole-body indirect calorimeter and to compare BU and doubly labelled water (DLW) measurements in free-living conditions in the same group of grossly obese women. DESIGN: Energy expenditure (EE) was estimated by the BU method over 24 h concurrently with whole-body indirect calorimetry and subsequently over 5 consecutive days at home concurrently with 14 day DLW. Six women, body mass index (BMI) 52.4+/-10.4 kg/m(2) (s.d.), were studied. RESULTS: Total energy expenditure (TEE) measurements by BU and GE within the metabolic chamber were not significantly different (BU=11.79+/-1.89 MJ/day and GE=11.64+/-1.86 MJ/day; mean difference, 0.25+/-0.49 MJ/day, P>0.05). Free-living TEE derived from BU and DLW was also similar (13.28+/-1.86 and 13.86+/-2.25 MJ/day, respectively; mean difference 0.17+/-1.33 MJ/day, P<0.05). The measured physical activity level (PAL) in these very obese subjects was within the range reported in other free-living studies in less obese individuals (1.62+/-0.14 using DLW and 1.56+/-0.20 using BU). The BU method was well tolerated by the subjects. CONCLUSIONS: This study in grossly obese subjects, heavier than those participating in previous studies involving tracer methods, demonstrates validity of the BU against GE under controlled metabolic conditions, and the equivalence between BU and DLW under free-living conditions. The results suggest that both tracer methods are valid in this population group. This study also demonstrates the practicalities of using the BU method over 5 days, the longest application of the method so far.