Jodi D. Stookey

Drinking water is associated with weight loss in overweight dieting women independent of diet and activity.

Background: Data from short‐term experiments suggest that drinking water may promote weight loss by lowering total energy intake and/or altering metabolism. The long‐term effects of drinking water on change in body weight and composition are unknown, however.

Replacing sweetened caloric beverages with drinking water is associated with lower energy intake.

Objective: Reduced intake of sweetened caloric beverages (SCBs) is recommended to lower total energy intake. Replacing SCBs with non‐caloric diet beverages does not automatically lower energy intake, however. Compensatory increases in other food or beverages reportedly negate benefits of diet beverages. The purpose of this study was to evaluate drinking water as an alternative to SCBs.

Hydration biomarkers in free-living adults with different levels of habitual fluid consumption

Little is known about the impact of habitual fluid intake on physiology. Specifically, biomarkers of hydration status and body water regulation have not been adequately explored in adults who consume different fluid volumes in everyday conditions, without prolonged exercise or environmental exposure. The purpose of the present study was to compare adults with habitually different fluid intakes with respect to biomarkers implicated in the assessment of hydration status, the regulation of total body water and the risk of kidney pathologies. In the present cross-sectional study, seventy-one adults (thirty-two men, thirty-nine women, age 25–40 years) were classified according to daily fluid intake: thirty-nine low drinkers (LD; ≤ 1·2 litres/d) and thirty-two high drinkers (HD; 2–4 litres/d). During four consecutive days, urinary parameters (first morning urine (FMU) on day 1 and subsequent 24 h urine (24hU) collections), blood parameters, and food and beverage intake were assessed. ANOVA and non-parametric comparisons revealed significant differences between the LD and HD groups in 24hU volume (1·0 (se 0·1) v. 2·4 (se 0·1) litres), specific gravity (median 1·023 v. 1·010), osmolality (767 (se 27) v. 371 (se 33) mOsm/kg) and colour (3·1 (se 0·2) v. 1·8 (se 0·2)). Similarly, in the FMU, the LD group produced a smaller amount of more concentrated urine. Plasma cortisol, creatinine and arginine vasopressin concentrations were significantly higher among the LD. Plasma osmolality was similar between the groups, suggesting physiological adaptations to preserve plasma osmolality despite low fluid intake. The long-term impact of adaptations to preserve plasma osmolality must be examined, particularly in the context of renal health.

Measuring diet quality in China: the INFH-UNC-CH diet quality index.

Objective: This paper describes the development and efficacy of a diet quality index (DQI) for China.Design: The Dietary Guidelines for Chinese Residents motivated the selection of 10 DQI components. These components were weighted and assigned cut-offs and point schemes based on the Chinese Food Guide Pagoda, Chinese and/or international dietary reference values. The efficacy of resulting DQI scores was assessed relative to a priori expectations.Subjects: The Chinese DQI was evaluated using cross-sectional 3 day diet record and anthropometric data on 7450 adults from the 1991 China Health and Nutrition Survey.Methods: For each individual, a DQI total score was calculated as the sum of components, and DQI pattern scores calculated to reflect the underlying composition of diet quality problems. The DQI scores were compared with component scores, food and nutrient intake, weight status and sociodemographic variables.Results: The total DQI score simultaneously represented all component aspects of diet quality as well as micronutrients not explicitly built into the index. The total DQI score was significantly correlated with food and nutrient intakes, BMI, urban residence and income. The DQI pattern scores correlated with DQI components and weight status as expected.Conclusions: The China DQI captures variation along several components of diet quality, appears sensitive to under- and overnutrition, as well as sociodemographic variables. The China DQI may prove useful for monitoring the nutrition transition and epidemiologic trends in China.Sponsorship: National Institutes of Health (HD 38700 and R01-HD30880) and the Chinese Academy of Preventive Medicine. European Journal of Clinical Nutrition (2000) 54, 811–821

What is the cell hydration status of healthy children in the USA? Preliminary data on urine osmolality and water intake.

OBJECTIVE Hyperosmotic stress on cells limits many aspects of cell function, metabolism and health. International data suggest that schoolchildren may be at risk of hyperosmotic stress on cells because of suboptimal water intake. The present study explored the cell hydration status of two samples of children in the USA. DESIGN Cross-sectional study describing the urine osmolality (an index of hyperosmotic cell shrinkage) and water intake of convenience samples from Los Angeles (LA) and New York City (NYC). SETTING Each participant collected a urine sample at an outpatient clinic on the way to school on a weekday morning in spring 2009. Each was instructed to wake, eat, drink and do as usual before school, and complete a dietary record form describing the type and amounts of all foods and beverages consumed after waking, before giving the sample. SUBJECTS The children (9-11 years) in LA (n 337) and NYC (n 211) considered themselves healthy enough to go to school on the day they gave the urine sample. RESULTS Elevated urine osmolality (>800 mmol/kg) was observed in 63 % and 66 % of participants in LA and NYC, respectively. In multivariable-adjusted logistic regression models, elevated urine osmolality was associated with not reporting intake of drinking water in the morning (LA: OR = 2·1, 95 % CI 1·2, 3·5; NYC: OR = 1·8, 95 % CI 1·0, 3·5). Although over 90 % of both samples had breakfast before giving the urine sample, 75 % did not drink water. CONCLUSIONS Research is warranted to confirm these results and pursue their potential health implications.

Relation between urinary hydration biomarkers and total fluid intake in healthy adults

Background/objectives:In sedentary adults, hydration is mostly influenced by total fluid intake and not by sweat losses; moreover, low daily fluid intake is associated with adverse health outcomes. This study aimed to model the relation between total fluid intake and urinary hydration biomarkers.Subjects/methods:During 4 consecutive weekdays, 82 adults (age, 31.6±4.3 years; body mass index, 23.2±2.7 kg/m2; 52% female) recorded food and fluid consumed, collected one first morning urine (FMU) void and three 24-h (24hU) samples. The strength of linear association between urinary hydration biomarkers and fluid intake volume was evaluated using simple linear regression and Pearson’s correlation. Multivariate partial least squares (PLS) modeled the association between fluid intake and 24hU hydration biomarkers.Results:Strong associations (|r|⩾0.6; P<0.001) were found between total fluid intake volume and 24hU osmolality, color, specific gravity (USG), volume and solute concentrations. Many 24hU biomarkers were collinear (osmolality versus color: r=0.49–0.76; USG versus color: r=0.46–0.78; osmolality versus USG: 0.86–0.97; P<0.001). Measures in FMU were not strongly correlated to intake. Multivariate PLS and simple linear regression using urine volume explained >50% of the variance in fluid intake volume (r2=0.59 and 0.52, respectively); however the error in both models was high and the limits of agreement very large.Conclusions:Hydration biomarkers in 24hU are strongly correlated with daily total fluid intake volume in sedentary adults in free-living conditions; however, the margin of error in the present models limits the applicability of estimating fluid intake from urinary biomarkers.

The altered fluid distribution in obesity may reflect plasma hypertonicity

Objective:This study explored whether the increased extracellular relative to intracellular fluid (ECF/ICF) ratio in obesity might reflect osmotic effects of elevated plasma solute concentrations.Design:Cross-sectional, epidemiological survey.Setting and subjects:The present analysis used nationally representative data from the Third National Health and Nutrition Examination Survey on community-dwelling adults (aged 40–59 years) in the US without evidence of glucose dysregulation or chronic disease (n=1285).Intervention:Body mass index (BMI) was estimated from measured height and weight. Total body reactance, an index of body fluid distribution, was determined by bioelectrical impedance analysis. Plasma tonicity (the cumulative index of osmotically effective plasma solute) was estimated from plasma glucose, sodium and potassium. Sex-specific relative odds of lower reactance (⩽50 Ω/m for women, ⩽40 Ω/m for men) and plasma hypertonicity (tonicity ⩾295 mmol/l) associated with overweight (25⩽BMI <30) and obesity (BMI⩾30) were estimated using logistic regression models that controlled for sociodemographic variables, smoking, leisure-time physical activity, total energy intake, serum creatinine, plasma insulin and glucose. Multinomial logistic regression models tested for associations between weight status and specific serum solute.Results:Independent of covariates, in men and women, overweight and obesity were associated with increased odds of lower reactance and hypertonicity. Overweight and obese individuals with lower reactance had significantly higher serum sodium than normal weight individuals.Conclusions:Elevated plasma solute concentrations are associated with obesity in free-living adults. Physicians and researchers should be alert to a possible link between hypertonicity and obesity.Descriptors:Hydration, body water, hypertonicity, obesity, ECF/ICF ratio, sodium.Sponsorship:Grants from the NIH, Nestle Waters.

A proposed method for assessing plasma hypertonicity in vivo.

Indices of plasma hypertonicity, elevated plasma concentrations of solutes that draw fluid out of cells by osmosis, are needed to pursue hypertonicity as a possible risk factor for obesity and chronic disease. This paper proposes a new index that may be more sensitive to mild hypertonicity in vivo at a point in time than traditional measures. The index compares mean corpuscular volume (MCV) estimates from diluted (in solution by automated cell counter) and nondiluted blood (calculated from manual hematocrit, MCV=Hct/RBC*106). A larger Auto vs Manual MCV (>2 fl) in vitro indicates hypertonicity in vivo if the cell counter diluent is isotonic with the threshold for plasma vasopressin (PVP) release and PVP is detectable in plasma (>0.5 pg/ml). To evaluate this principle of concept, hypertonicity was induced by 24-h fluid restriction after a 20 ml/kg water load in four healthy men (20–46 years). Unlike serum and urine indices, the MCV difference-&-PVP index detected hypertonicity in all participants.

From State to Process: Defining Hydration

a Danone Nutricia Research, Palaiseau , France, b Human Performance Laboratory, Department of Kinesiology and Department of Nutritional Sciences, University of Connecticut, Storrs, CT , USA, c Service d’Explorations Fonctionnelles, Hopital Tenon, Paris , France, d Human Performance Laboratory, Department of Health and Human Performance, University of Arkansas, Fayetteville, AR , USA, e INSERM/UPS UMR 1048-I2MC, Hopital Rangueil, Universite Paul Sabatier, Toulouse , France, f Institute of Physiology, University of Tubingen, Tubingen , Germany, g Departement de kinesiologie, Universite de Montreal, Montreal, QC , Canada, h Children’s Hospital Oakland Research Institute, Oakland, CA , USA, i Service des Explorations Fonctionnelles Physiologiques et INSERM 1048 – Equipe 12, CHU de Rangueil, Toulouse , France

Orange Juice Limits Postprandial Fat Oxidation after Breakfast in Normal-Weight Adolescents and Adults

Caloric beverages may promote weight gain by simultaneously increasing total energy intake and limiting fat oxidation. During moderate intensity exercise, caloric beverage intake depresses fat oxidation by 25% or more. This randomized crossover study describes the impact of having a caloric beverage with a typical meal on fat oxidation under resting conditions. On 2 separate days, healthy normal-weight adolescents (n = 7) and adults (n = 10) consumed the same breakfast with either orange juice or drinking water and sat at rest for 3 h after breakfast. The meal paired with orange juice was 882 kJ (210 kcal) higher than the meal paired with drinking water. Both meals contained the same amount of fat (12 g). For both age groups, both meals resulted in a net positive energy balance 150 min after breakfast. Resting fat oxidation 150 min after breakfast was significantly lower after breakfast with orange juice, however. The results suggest that, independent of a state of energy excess, when individuals have a caloric beverage instead of drinking water with a meal, they are less likely to oxidize the amount of fat consumed in the meal before their next meal.