Water consumption reduces energy intake at a breakfast meal in obese older adults

Water intake and obesity: By amount, timing, and perceived temperature of drinking water

Water intake has been suggested to be associated with weight control, but evidence for optimal water intake in terms of amount, timing, and temperature is sparse. Additionally, genetic predisposition to obesity, which affects satiety and energy expenditure, might interact with water intake in regulating individual adiposity risk. We conducted a cross-sectional study recruiting 172 Korean adults. Information on water intake and lifestyle factors was collected through self-reported questionnaires, and height, weight, and waist circumference (WC) were measured by researchers. The oral buccal swab was performed for genotyping of FTO rs9939609, MC4R rs17782313, BDNF rs6265 and genetic risk of obesity was calculated. Linear regression was performed to estimate mean difference in body mass index (BMI) and WC by water intake and its 95% confidence interval (95% CI). As a sensitivity analysis, logistic regression was performed to estimate odds ratio (OR) of obesity/overweight (BMI of ≥23kg/m2; WC of ≥90cm for men and of ≥80cm for women) and its 95% CI. Drinking >1L/day was significantly associated with higher BMI (mean difference: 0.90, 95% CI 0.09, 1.72) and WC (mean difference: 3.01, 95% CI 0.62, 5.41) compared with drinking ≤1L/day. Independent of total water intake, drinking before bedtime was significantly associated with lower BMI (mean difference: -0.98, 95% CI -1.91, -0.05). The results remained consistent when continuous BMI and WC were analyzed as categorical outcomes. By perceived temperature, drinking >1L/day of cold water was associated with higher BMI and WC compared with drinking ≤1L/day of water at room-temperature. By genetic predisposition to obesity, a positive association between water intake and WC was confined to participants with low genetic risk of obesity (P interaction = 0.04). In conclusion, amount, timing, and perceived temperature of water intake may be associated with adiposity risk and the associations might vary according to genetic predisposition to obesity.

Water Intake and Adiposity Outcomes among Overweight and Obese Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Water consumption is believed to be a key factor in weight management strategies, yet the existing literature on the subject yields inconsistent findings. To systematically assess the scientific evidence regarding the effect of water intake on adiposity, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) among overweight and obese populations.

METHODS

PubMed and Embase were searched for relevant articles published up to December 2023. The summary weighted mean difference (WMD) and 95% confidence interval (CI) were estimated using the DerSimonian-Laird random-effects model.

RESULTS

In this meta-analysis of eight RCTs, interventions to promote water intake or to substitute water for other beverages as compared to the control group resulted in a summary WMD of -0.33 kg (95% CI = -1.75-1.08, I2 = 78%) for body weight, -0.23 kg/m2 (95% CI = -0.55-0.09, I2 = 0%) for body mass index (BMI), and 0.05 cm (95% CI = -1.20-1.30, I2 = 40%) for waist circumference (WC). Among RCTs substituting water for artificially sweetened beverages, summary WMD was 1.82 kg (95% CI = 0.97-2.67, I2 = 0%) for body weight and 1.23 cm (95% CI = -0.03-2.48, I2 = 0%) for WC. Conversely, among RCTs substituting water for sugar-sweetened beverages, summary WMD was -0.81 kg (95% CI = -1.66-0.03, I2 = 2%) for body weight and -0.96 cm (95% CI = -2.06-0.13, I2 = 0%) for WC.

CONCLUSIONS

In conclusion, water intake may not significantly impact adiposity among overweight and obese individuals. However, replacing sugar-sweetened beverages with water might offer a modest benefit in inducing weight loss.

Comprehensive Approach to Medical Nutrition Therapy in Patients with Type 2 Diabetes Mellitus: From Diet to Bioactive Compounds

In the pathogenesis of type 2 diabetes mellitus (T2DM), diet plays a key role. Individualized medical nutritional therapy, as part of lifestyle optimization, is one of the cornerstones for the management of T2DM and has been shown to improve metabolic outcomes. This paper discusses major aspects of the nutritional intervention (including macro- and micronutrients, nutraceuticals, and supplements), with key practical advice. Various eating patterns, such as the Mediterranean-style, low-carbohydrate, vegetarian or plant-based diets, as well as healthy eating plans with caloric deficits have been proven to have beneficial effects for patients with T2DM. So far, the evidence does not support a specific macronutrient distribution and meal plans should be individualized. Reducing the overall carbohydrate intake and replacing high glycemic index (GI) foods with low GI foods have been shown as valid options for patients with T2DM to improve glycemic control. Additionally, evidence supports the current recommendation to reduce the intake of free sugars to less than 10% of total energy intake, since their excessive intake promotes weight gain. The quality of fats seems to be rather important and the substitution of saturated and trans fatty acids with foods rich in monounsaturated and polyunsaturated fats lowers cardiovascular risk and improves glucose metabolism. There is no benefit of supplementation with antioxidants, such as carotene, vitamins E and C, or other micronutrients, due to the lack of consistent evidence showing efficacy and long-term safety. Some studies suggest possible beneficial metabolic effects of nutraceuticals in patients with T2DM, but more evidence about their efficacy and safety is still needed.

Characterization of Metallic Off-Flavors in Drinking Water: Health, Consumption, and Sensory Perception

Characterization of taste- and flavor-producing metals, namely iron and copper, in drinking water is a multifaceted subject. Both metals are essential nutrients, can be toxic, and are known to produce unpleasant tastes and flavor sensations in drinking water. Ingestion of trace metal contaminants through drinking water is a probable source of human exposure. Biochemical mechanisms of metallic flavor perception have been previously described; however, less is known about how variations in salivary constituents might impact individuals' sensitivities to metallic flavors and beverage consumption behaviors. This research presents findings from in vitro experiments, using artificial human saliva, to better understand the role of salivary lipids and proteins on metallic flavor production as measured by biomarkers of metal-induced oxidative stress. The results indicate that metal-induced lipid oxidation, as measured by thiobarbituric acid reactive substances (TBARS), is dominated by salivary proteins, is slightly inhibited in the presence of salivary nitrite, and is detectable by the TBARS method at and above respective concentrations of 9 µM (0.5 mg/L) and 90 µM (5 mg/L), which are both above the aesthetic standards for iron (0.3 mg/L) and copper (1.0 mg/L) in drinking water. Preliminary study with human subjects indicated that reduction in metallic flavor sensitivity, as measured by the best estimate flavor threshold for ferrous iron among 33 healthy adults aged 19-84 years old (22 females), corresponded with reduced drinking water consumption and increased caloric beverage intake among older subjects (>60 years), as determined by a validated self-reported beverage intake questionnaire. These findings provide insights for further research to examine how salivary constituents can impact humans' sensory abilities in detecting metallic off-flavors in water, and how reduced metallic flavor sensitivity may influence beverage choices and drinking water consumption.

Baseline drinking water consumption and changes in body weight and waist circumference at 2-years of follow-up in a senior Mediterranean population

BACKGROUND & AIMS

The association between drinking water consumption and adiposity has been poorly explored. Therefore, we aimed to analyse the associations between the frequency of drinking water consumption and body weight and waist circumference changes in an elderly Mediterranean cohort.

METHODS

A total of 1832 elderly participants (aged 55-75 years) with metabolic syndrome from the PREDIMED-Plus study with baseline data on drinking water and other beverages assessed by a validated 32-item Spanish fluid-intake questionnaire and with data on body weight (BW) and waist circumference (WC) at 1-year and 2-year were included in these prospective analyses. Multivariable linear regression models were fitted to assess the β-coefficients and 95% confidence interval (CI) for BW and WC changes in terms of categories of baseline drinking water consumption (tap water and bottled water). The theoretical effect on BW and WC of replacing several beverages with drinking water was assessed using mathematical models.

RESULTS

The baseline frequency of drinking water consumption was inversely associated with 1-year and 2-year changes in BW. β-coefficients (95%CI) across categories of water consumption (<2.5, 2.5 to <5, 5 to < 7.5, ≥7.5 servings/d) expressed in % of weight changes at 2 years of follow-up were 0.0, -0.80 (-1.48, -0.12), -1.36 (-2.18, -0.54), and -1.97 (-3.09, -0.86), respectively. Individuals in the two highest categories of drinking water consumption (5 to < 7, and ≥7.5 servings/d) also showed a higher decrease in WC (expressed as % of change) after 2 years of follow-up: -1.11 (-1.96, -0.25) and -1.45 (-2.66, -0.24) compared to the reference intake (<2.5 servings/day), after adjustment for potential confounding factors. The theoretical replacement of soups, beers, spirits, hot beverages, dairy beverages, and other beverages group with drinking water was associated with greater reductions in BW at one- and two-years of follow-up.

CONCLUSIONS

Drinking water consumption was inversely associated with 2-year adiposity changes in an elderly Mediterranean cohort at high cardiovascular risk. Our results also suggest that the consumption of drinking water instead of energy-containing beverages is associated with lower weight gain.

THE TRIAL REGISTRATION

ISRCTN89898870.

The Impact of Post-Prandial Delay Periods on Ad Libitum Consumption of a Laboratory Breakfast Meal

This study examined the impact of varying the holding time following an ad libitum laboratory breakfast on acute dietary behaviour and subsequent intake. 24 participants (20 females (age: 23.4±6.3 y; BMI: 23.9±3.9 kg·m-2, mean±SD)) completed three trials following a quasi-randomized, crossover design. Each trial (seven day separation) incorporated a defined post-prandial delay (DPD) period of either zero (no delay), one or three hours following a buffet breakfast consumed over 30-minutes. Dietary intake outcomes included energy, macronutrient and core food group intakes. On completion of the DPD period, participants left the laboratory and recorded all food/beverages consumed for the remainder of the day. One-way repeated-measures ANOVA assessed all outcomes, with post hoc analysis conducted on significant main effects. Energy and carbohydrate intakes were significantly lower on no delay vs one hour (p = 0.014) and three hour (p = 0.06) DPD trials (EI: 1853±814 kJ vs. 2250±1345 kJ vs. 1948±1289 kJ; CHO: 68±34 g vs. 77±44 vs. 69±43 g; respectively). DPD periods did not influence the time to consume next meal or energy, macronutrient and core food group intakes for the remainder of the day. Delaying participants from leaving a laboratory alters dietary intake at an ad libitum test meal. The post-meal holding period is an important methodological consideration when planning laboratory studies to assess appetite. Novelty Bullets: 1. Delaying participants from leaving a laboratory alters dietary intake at ad libitum breakfast meals. 2. The length of the delay period did not affect dietary intake at ad libitum breakfast meals.

Effect of pre-meal water intake on the serum levels of Copeptin, glycemic control, lipid profile and anthropometric indices in patients with type 2 diabetes mellitus: a randomized, controlled trial

Background

Water pre-load affects insulin secretion by altering the level of copeptin (C-terminal component of the arginine vasopressin hormone (AVP)) and preventing obesity by reducing food intake.

Aims

The present randomized controlled trial (RCT) aimed to investigate the effects of pre-meal water intake on type 2 diabetes Mellitus (T2DM).

Materials and methods

In this study, 40 patients with T2DM were randomly assigned to two intervention groups for 8 weeks; a) drinking 1 liter of water per day before each main meal (PW group)., and b) no water consumption before any meal (NPW group). At the beginning and at the end of the study, blood samples were taken to assess glycemic indices, lipid profile, copeptin and anthropometric indices.

Results

Pre-meal water intake was associated with lower energy intake, BMI, waist circumference (WC) and greater weight loss, in compared with the controls (P < 0.0001) after 8 weeks. At the end of the trial, the concentrations of fasting blood sugar (FBS) (P < 0.0001), triglyceride (TG) (P < 0.05), low-density lipoprotein cholesterol (LDL-C) (P < 0.05) and copeptin (P < 0.05) were significantly reduced following water drinking before meals.

Conclusion

To sum up, the present study revealed that pre-meal water intake is associated with lower BMI, body weight, WC, FBS, TG, LDL-C and copeptin levels in patients with T2DM.

A cluster-randomized controlled trial of an elementary school drinking water access and promotion intervention: Rationale, study design, and protocol

INTRODUCTION

Promoting water consumption among children in schools is a promising intervention to reduce sugar-sweetened beverage (SSB) intake and achieve healthful weight. To date, no studies in the United States have examined how a school-based water access and promotion intervention affects students' beverage and food intake both in and out of school and weight gain over time. The Water First trial is intended to evaluate these interventions.

METHODS

Informed by the PRECEDE-PROCEED model and Social Cognitive Theory, the Water First intervention includes: 1) installation of lead-free water stations in cafeterias, physical activity spaces, and high-traffic common areas in lower-income public elementary schools, 2) provision of cups/reusable water bottles for students, and 3) a 6-month healthy beverage education campaign. A five year-long cluster randomized controlled trial of 26 low-income public elementary schools in the San Francisco Bay Area is examining how Water First impacts students' consumption of water, caloric intake from foods and beverages, and BMI z-score and overweight/obesity prevalence, from baseline to 7 months and 15 months after the start of the study. Intervention impact on outcomes will be examined using a difference-in-differences approach with mixed-effects regression accounting for the clustering of students in schools and classrooms.

DISCUSSION

This paper describes the rationale, study design, and protocol for the Water First study. If the intervention is effective, findings will inform best practices for implementing school water policies, as well as the development of more expansive policies and programs to promote and improve access to drinking water in schools.

The Effect of Acute Hypohydration on Indicators of Glycemic Regulation, Appetite, Metabolism and Stress: A Systematic Review and Meta-Analysis

Evidence synthesizing the effects of acute body water losses on various markers of glycemic regulation, appetite, metabolism, and stress is lacking. Thus, the purpose of this review was to summarize the response of various hormonal changes involved in these physiologic functions to dehydration. A comprehensive literature search for peer-reviewed research in the databases PubMed, Scopus, CINAHL, and SportDiscus was conducted. Studies were included if they contained samples of adults (>18 years) and experimentally induced dehydration as measured by acute body mass loss. Twenty-one articles were eligible for inclusion. Findings suggested cortisol is significantly elevated with hypohydration (standard mean difference [SMD] = 1.12, 95% CI [0.583, 1.67], p < 0.0001). Testosterone was significantly lower in studies where hypohydration was accompanied by caloric restriction (SMD= -1.04, 95% CI [-1.93, -0.14], p = 0.02), however, there were no changes in testosterone in studies examining hypohydration alone (SMD = -0.17, 95% CI [-0.51 0.16], p = 0.30). Insulin and ghrelin were unaffected by acute total body water losses. Acute hypohydration increases markers of catabolism but has a negligible effect on markers of glycemic regulation, appetite, anabolism and stress. Given the brevity of existing research, further research is needed to determine the impact of hydration on glucagon, leptin, peptide YY and the subsequent outcomes relevant to both health and performance.

Protein Status Modulates an Appetite for Protein To Maintain a Balanced Nutritional State-A Perspective View

Protein sufficiency is tightly controlled through different sensing and signaling processes that modulate and adapt protein and energy metabolism and feeding behavior to reach and maintain a well-balanced protein status. High-protein diets, often discussed in the context of body weight management, usually activate anorexigenic pathways, leading to higher satiety, decreased food and energy intake, and decreased body weight and adiposity. Diets marginally low in protein (3-8% energy) or marginally deficient in some indispensable amino acid more often activate orexigenic pathways, with higher appetite and a specific appetite for protein, a response that leads to an increase in protein intake to partially compensate for the deficit in protein and amino acid. Diets severely deficient in protein (2-3% energy as protein) usually depress food intake and induce lower weight and lower fat mass and lean tissues that characterize a status of protein deficiency. The control of protein sufficiency involves various peripheral and central signals, including modulation of both metabolic pathways at the periphery as well as central pathways of the control of food and protein intake, including a reward-driven specific sensitivity to the protein content of foods.

Αcute effects of essential amino acid gel-based and whey protein supplements on appetite and energy intake in older women

Deficiencies in protein and energy intakes are partly responsible for age-related sarcopenia. We investigated the effects of supplements matched in essential amino acid (EAA) content (7.5 g) on energy intake and appetite. Ten women aged 69.2 ± 2.7 years completed 3 trials in a randomised, crossover design. Composite appetite scores, peptide-YY (PYY), and insulin responses to a 200-mL whey protein (WP) isolate (275 kJ), a 50-mL EAA gel (GEL, 478 kJ), or nothing as the control (CON) condition were investigated over 1 h, followed by an ad libitum breakfast. Energy intake at breakfast (CON, 1957 ± 713; WP, 1413 ± 623; GEL, 1963 ± 611 kJ) was higher in CON and GEL than in WP (both P = 0.006). After accounting for supplement energy content, energy intake in GEL was higher than in CON (P = 0.0006) and WP (P = 0.0008). Time-averaged area under the curve for composite appetite scores (CON, 74 ± 20; WP, 50 ± 22; GEL, 60 ± 16 mm) was higher in CON than WP (P = 0.015). Time-averaged area under the curve for PYY (CON, 87 ± 13; WP, 119 ± 27; GEL, 97 ± 22 pg·mL−1) was higher in WP than CON (P = 0.009) and GEL (P = 0.012). In conclusion, supplementation with WP facilitated an increase in protein intake, whereas supplementation with GEL increases in both energy and protein intakes, when consumed before an ad libitum breakfast. Such findings highlight potential gel-based EAA supplementation intake for addressing age-related sarcopenia.

Influence of Water Intake and Balance on Body Composition in Healthy Young Adults from Spain

The increasing prevalence of overweight and obesity has become an epidemic public health problem worldwide. In the last years, several investigations have suggested that water intake and retention could have important implications for both weight management and body composition. However, there is a lack of information about this issue globally, and mainly specifically in Spain. Thus, the aim of this study was to analyze the association between hydration status and body composition in a sample of healthy Spanish adults. The study involved 358 subjects, aged 18-39 years. The recently validated "hydration status questionnaire" was used to assess their water intake, elimination, and balance. Anthropometric measurements were performed according to the recommendations of the International Standards for Anthropometric Assessment (ISAK). Body composition variables were acquired by bioelectrical impedance analysis. Differences in anthropometric and body composition variables were assessed through the ANOVA test and considered significant at p < 0.05. Fluid intake was correlated with body water content. Inverse associations between water consumption, normalized by weight, with body weight, body fat mass, and waist circumference were found. Moreover, according to water balance, significant differences in body water content in females were observed. In conclusion, higher fluid intake seems to be related with a healthier body composition. Therefore, the improvement of water intake and water balance could be useful for overweight and obesity prevention, although further studies are needed to confirm the present findings.

Of Mice and Men-The Physiology, Psychology, and Pathology of Overhydration

The detrimental effects of dehydration, to both mental and physical health, are well-described. The potential adverse consequences of overhydration, however, are less understood. The difficulty for most humans to routinely ingest ≥2 liters (L)-or "eight glasses"-of water per day highlights the likely presence of an inhibitory neural circuit which limits the deleterious consequences of overdrinking in mammals but can be consciously overridden in humans. This review summarizes the existing data obtained from both animal (mostly rodent) and human studies regarding the physiology, psychology, and pathology of overhydration. The physiology section will highlight the molecular strength and significance of aquaporin-2 (AQP2) water channel downregulation, in response to chronic anti-diuretic hormone suppression. Absence of the anti-diuretic hormone, arginine vasopressin (AVP), facilitates copious free water urinary excretion (polyuria) in equal volumes to polydipsia to maintain plasma tonicity within normal physiological limits. The psychology section will highlight reasons why humans and rodents may volitionally overdrink, likely in response to anxiety or social isolation whereas polydipsia triggers mesolimbic reward pathways. Lastly, the potential acute (water intoxication) and chronic (urinary bladder distension, ureter dilation and hydronephrosis) pathologies associated with overhydration will be examined largely from the perspective of human case reports and early animal trials.

Effects of a Paleolithic Diet on Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

There is some evidence supporting the beneficial effects of a Paleolithic Diet (PD) on cardiovascular disease risk factors. This diet advises consuming lean meat, fish, vegetables, fruits, and nuts and avoiding intake of grains, dairy products, processed foods, and added sugar and salt. This study was performed to assess the effects of a PD on cardiovascular disease risk factors including anthropometric indexes, lipid profile, blood pressure, and inflammatory markers using data from randomized controlled trials. A comprehensive search was performed in the PubMed, Scopus, ISI Web of Science, and Google Scholar databases up to August, 2018. A meta-analysis was performed using a random-effects model to estimate the pooled effect size. Meta-analysis of 8 eligible studies revealed that a PD significantly reduced body weight [weighted mean difference (WMD) = -2.17 kg; 95% CI: -3.48, -0.87 kg], waist circumference (WMD = -2.90 cm; 95% CI: -4.51, -1.28 cm), body mass index (in kg/m2) (WMD = -1.15; 95% CI: -1.68, -0.62), body fat percentage (WMD = -1.38%; 95% CI: -2.08%, -0.67%), systolic (WMD = -4.24 mm Hg; 95% CI: -7.11, -1.38 mm Hg) and diastolic (WMD = -2.95 mm Hg; 95% CI: -4.72, -1.18 mm Hg) blood pressure, and circulating concentrations of total cholesterol (WMD = -0.22 mg/dL; 95% CI: -0.42, -0.03 mg/dL), TGs (WMD = -0.23 mg/dL; 95% CI: -0.46, -0.01 mg/dL), LDL cholesterol (WMD = -0.13 mg/dL; 95% CI: -0.25, -0.01 mg/dL), and C-reactive protein (CRP) (WMD = -0.41 mg/L; 95% CI: -0.81, -0.008 mg/L) and also significantly increased HDL cholesterol (WMD = 0.05 mg/dL; 95% CI: 0.005, 0.10 mg/dL). However, sensitivity analysis revealed that the overall effects of a PD on lipid profile, blood pressure, and circulating CRP concentrations were significantly influenced by removing some studies, hence the results must be interpreted with caution. Although the present meta-analysis revealed that a PD has favorable effects on cardiovascular disease risk factors, the evidence is not conclusive and more well-designed trials are still needed.

The effects of water temperature on gastric motility and energy intake in healthy young men

Purpose

Although immediate pre-meal water ingestion has been shown to reduce energy intake in healthy young men, no studies are available regarding potential mechanisms underlying the effect of energy intake in response to different temperatures of pre-meal water ingestion. This study examined the effects of consuming different temperatures of water on gastric motility and energy intake in healthy young men.

Methods

Eleven young men were completed three, 1-day trials in a random order. Subjects visited the laboratory after a 10-h overnight fast and consumed 500 mL of water at 2 °C, 37 °C, or 60 °C in 5 min. Then, subjects sat on a chair over 1 h to measure the cross-sectional gastric antral area and gastric contractions using the ultrasound imaging systems. Thereafter, subjects consumed a test meal until they felt completely full. Energy intake was calculated from the amount of food consumed.

Results

Energy intake in the 2 °C (6.7 ± 1.8 MJ) trial was 19% and 26% lower than the 37 °C (7.9 ± 2.3 MJ, p = 0.039) and 60 °C (8.5 ± 3.2 MJ, p = 0.025) trials, respectively. The frequency of the gastric contractions after 1-h consuming water was lowered in the 2 °C trial than the 60 °C trial (trial-time interaction, p = 0.020). The frequency of gastric contractions was positively related to energy intake (r = 0.365, p = 0.037).

Conclusions

These findings demonstrate that consuming water at 2 °C reduces energy intake and this reduction may be related to the modulation of the gastric motility.

Effect of Pre-meal Water Consumption on Energy Intake and Satiety in Non-obese Young Adults

I determined whether water consumption reduces energy intake and affects satiety in non-obese young adults. The final subjects consisted of 15 individuals (8 women and 7 men) with average ages of 26.4 and 23.5 years for women and men, respectively. When subjects drank water before eating a test meal, they ate a lower amount of the test meal compared to eating test meals under waterless and postload water conditions (preload water: 123.3 g vs. waterless: 161.7 g or postload water: 163.3 g, p < 0.05). Water consumption after eating a test meal did not affect energy intake. When the subjects drank water before eating a test meal, despite consuming a lower amount, the subjects did not feel significantly less satiety than eating meals under waterless or postload water conditions. The finding that pre-meal water consumption led to a significant reduction in meal energy intake in young adults suggests that pre-meal water consumption may be an effective weight control strategy, although the mechanism of action is unknown.

Increasing water intake influences hunger and food preference, but does not reliably suppress energy intake in adults

Increasing water intake is often purported to reduce energy intake, and is recommended as a weight loss strategy. The few experimental studies that have been conducted to verify these claims have examined the impact of a single pre-load of water before a meal. Although correlational data indicate a relationship between hydration, energy intake, and weight status, there is very little experimental research in this area. The current studies examined the hypothesis that elevated hydration, through increased water intake, would suppress energy intake. In Experiment 1, participants (n = 49) were asked to consume either one, two, or three 500 ml bottles of water throughout the morning before a lunch buffet in the laboratory. When participants categorized as normal weight drank three bottles of water they consumed less energy at lunch, but there was no effect on participants categorized as overweight or obese. In addition, increased water intake suppressed liking of food items in all participants and hunger in females. A follow-up study (n = 45) was conducted to test if four bottles of water throughout the morning would result in a similar energy suppression in participants categorized as overweight or obese. Surprisingly, in the second experiment, there was no effect of water intake on energy intake at lunch in any of the conditions. There was, however, a similar suppression of hunger and food liking. In conclusion, increasing water intake throughout the morning only suppressed energy intake in individuals categorized as normal weight under certain circumstances, and had no effect on individuals categorized as overweight/obese.

Drinking water with consumption of a jelly filled doughnut has a time dependent effect on the postprandial blood glucose level in healthy young individuals

An elevated postprandial glucose (PPG) level in plasma or blood is a risk factor for chronic disorders like obesity, diabetes mellitus type II and related cardiovascular conditions. Therefore, it is important to identify mechanisms that increase the value of postprandial glucose PPG levels. Hence in the present study we investigated the time dependent effect of drinking water during a meal on the level of PPG. Thirty-five volunteers were randomly assigned to five groups. Group A was given a jelly filled doughnut and group B, C, D and E had a similar doughnut in combination with a bottle of water along with the doughnut, thirty minutes before, thirty minutes after, and a second doughnut with water thirty minutes after the first one, respectively. Glucose was measured in capillary blood at intervals of 30 min up to 150 min (reg # FMeW 725B/17). PPG versus fasting glucose (Means ± SD, mmol/L) was for group A 5.4 ± 0.6 vs 4.6 ± 0.4, B 7.2 ± 0.7 vs 4.9 ± 0.4, C 5.5 ± 0.7 vs 4.4 ± 0.3, D 5.5 ± 0.6 vs 4.6 ± 0.3 and E 5.7 ± 0.5 vs 4.7 ± 0.2. The increase in group B was significantly higher than in all other groups (ANOVA, Dunnet's posttest). These results show that drinking water with consumption of a jelly-filled doughnut increases the postprandial blood glucose levels significantly compared to no drinking at all or thirty minutes before or after the consumption. It is therefore advisable that we should reconsider our eating and drinking habits to lower the PPG and consequently reduce the risks of abovementioned chronic disorders. Further assessment is necessary to evaluate this in more detail.

Long-Term Intake of a High-Protein Diet Affects Body Phenotype, Metabolism, and Plasma Hormones in Mice

Background: High-protein diets (HPDs) recently have been used to obtain body weight and fat mass loss and expand muscle mass. Several studies have documented that HPDs reduce appetite and food intake.Objective: Our goal was to determine the long-term effects of an HPD on body weight, energy intake and expenditure, and metabolic hormones.Methods: Male C57BL/6 mice (8 wk old) were fed either an HPD (60% of energy as protein) or a control diet (CD; 20% of energy as protein) for 12 wk. Body composition and food intakes were determined, and plasma hormone concentrations were measured in mice after being fed and after overnight feed deprivation at several time points.Results: HPD mice had significantly lower body weight (in means ± SEMs; 25.73 ± 1.49 compared with 32.5 ± 1.31 g; P = 0.003) and fat mass (9.55% ± 1.24% compared with 15.78% ± 2.07%; P = 0.05) during the first 6 wk compared with CD mice, and higher lean mass throughout the study starting at week 2 (85.45% ± 2.25% compared with 75.29% ± 1.90%; P = 0.0001). Energy intake, total energy expenditure, and respiratory quotient were significantly lower in HPD compared with CD mice as shown by cumulative energy intake and eating rate. Water vapor was significantly higher in HPD mice during both dark and light phases. In HPD mice, concentrations of leptin [feed-deprived: 41.31 ± 11.60 compared with 3041 ± 683 pg/mL (P = 0.0004); postprandial: 112.5 ± 102.0 compared with 8273 ± 1415 pg/mL (P < 0.0001)] and glucagon-like peptide 1 (GLP-1) [feed-deprived: 5.664 ± 1.44 compared with 21.31 ± 1.26 pg/mL (P = <0.0001); postprandial: 6.54 ± 2.13 compared with 50.62 ± 11.93 pg/mL (P = 0.0037)] were significantly lower, whereas postprandial glucagon concentrations were higher than in CD-fed mice.Conclusions: In male mice, the 12-wk HPD resulted in short-term body weight and fat mass loss, but throughout the study preserved body lean mass and significantly reduced energy intake and expenditure as well as leptin and GLP-1 concentrations while elevating postprandial glucagon concentrations. This study suggests that long-term use of HPDs may be an effective strategy to decrease energy intake and expenditure and to maintain body lean mass.

Attenuating the Biologic Drive for Weight Regain Following Weight Loss: Must What Goes Down Always Go Back Up?

Metabolic adaptations occur with weight loss that result in increased hunger with discordant simultaneous reductions in energy requirements—producing the so-called energy gap in which more energy is desired than is required. The increased hunger is associated with elevation of the orexigenic hormone ghrelin and decrements in anorexigenic hormones. The lower total daily energy expenditure with diet-induced weight loss results from (1) a disproportionately greater decrease in circulating leptin and resting metabolic rate (RMR) than would be predicted based on the decline in body mass, (2) decreased thermic effect of food (TEF), and (3) increased energy efficiency at work intensities characteristic of activities of daily living. These metabolic adaptations can readily promote weight regain. While more experimental research is needed to identify effective strategies to narrow the energy gap and attenuate weight regain, some factors contributing to long-term weight loss maintenance have been identified. Less hunger and greater satiation have been associated with higher intakes of protein and dietary fiber, and lower glycemic load diets. High levels of physical activity are characteristic of most successful weight maintainers. A high energy flux state characterized by high daily energy expenditure and matching energy intake may attenuate the declines in RMR and TEF, and may also result in more accurate regulation of energy intake to match daily energy expenditure.

Pre-meal inulin consumption does not affect acute energy intake in overweight and obese middle-aged and older adults: A randomized controlled crossover pilot trial

BACKGROUND

Three-fourths of adults older than 55 years in the United States are overweight or obese. Prebiotics including inulin-type fructans may benefit with weight management.

AIM

We aimed to investigate the acute effects of pre-meal inulin consumption on energy intake (EI) and appetite in older adults.

METHODS

Sedentary, overweight or obese middle-aged and older adults ( n = 7, 60.9 ± 4.4 years, BMI 32.9 ± 4.3 kg/m²) ingested inulin (10 g) or a water preload before each test period in a randomly assigned order. EI, appetite and gastrointestinal symptoms were monitored during the following 24 h.

RESULTS

No differences in EI were noted between conditions (inulin: 14744 ± 5552 kJ, control: 13924 ± 4904 kJ, p > 0.05). Rumbling was increased with inulin consumption ( p < 0.05).

CONCLUSION

Pre-meal inulin consumption does not acutely decrease EI or suppress appetite in older adults. Further research should address individual differences among diets, eating behaviors, and microbiota profiles.

Dietary quality changes in response to a sugar-sweetened beverage-reduction intervention: results from the Talking Health randomized controlled clinical trial

Background: The reduction of sugar-sweetened beverage (SSB) intake may be beneficial for weight management and other related health conditions; however, to our knowledge, no data exist regarding the spontaneous changes in other dietary components or the overall dietary quality after an SSB-reduction intervention.Objectives: We explored longitudinal changes within and between an SSB-reduction intervention (SIPsmartER) and a physical activity intervention (MoveMore) with respect to spontaneous changes in 1) energy intake and macronutrients and micronutrients, 2) dietary quality [Healthy Eating Index-2010 (HEI)], and 3) beverage categories.Design: Participants were enrolled in a 6-mo, community-based behavioral trial and randomly assigned into either the SIPsmartER (n = 149) intervention group or the MoveMore (n = 143) matched-contact comparison group. Dietary intake was assessed through a mean of three 24-h dietary recalls at baseline and 6 mo. Dietary recalls were analyzed with the use of nutritional analysis software. A multilevel, mixed-effects linear regression with intention-to-treat analyses is presented.Results: SIPsmartER participants showed a significant reduction in total SSBs (mean decrease: -366 mL; P ≤ 0.001). Several spontaneous changes occurred within the SIPsmartER group and, compared with the MoveMore group, included significant HEI improvements for empty calorie, total vegetable, and total HEI scores (mean increases: 2.6, 0.3, and 2.6, respectively; all P ≤ 0.01). Additional positive changes were shown, including significant decreases in total energy intake, trans fat, added sugars, and total beverage energy (all P ≤ 0.05). Few dietary changes were noted in the MoveMore group over the 6-mo intervention.Conclusions: Intervention of the single dietary component SSB resulted in additional spontaneous and beneficial dietary changes. Interventions that target a single dietary change, such as limiting SSB intake to <240 mL/d (<8 fl oz/d), may improve the overall dietary quality health and provide motivation to make additional dietary changes. This trial was registered at clinicaltrials.gov as NCT02193009.

Modeling the Effect of Replacing Sugar-Sweetened Beverage Consumption with Water on Energy Intake, HBI Score, and Obesity Prevalence

Sugar-sweetened beverages (SSB) contribute to excessive weight gain through added energy intake. Replacing SSB with water is one strategy that has shown promise in helping lower excessive energy intake. Using nationally representative data from US adults (n = 19,718) from NHANES 2007–2012 we examine the impact of replacing SSB with water on Healthy Beverage Index (HBI) scores and obesity prevalence. Replacing an 8-ounce serving of SSB with water lowered the percent of energy from beverages from 17% to 11% (among those consuming 1 serving SSB/day). Reductions in the percent energy from beverages were observed across all SSB consumption groups (1–2 servings/day and >2 servings/day). Among adults there was a 9% to 21% improvement in HBI score when one serving of water replaced one serving of SSB. Using previously published randomized controlled trials (RCT) and meta-analyses of measured weight loss we also predicted a reduction in the prevalence of obesity (observed: 35.2%; predicted 33.5%–34.9%, p < 0.05) and increase in the prevalence of normal weight (observed: 29.7%; high weight loss: 31.3%, p < 0.05). Our findings provide further epidemiologic evidence that water in the place of SSB can be used as a strategy to limit energy intake and help individuals meet beverage intake recommendations.

Increased Hydration Can Be Associated with Weight Loss

This mini-review develops the hypothesis that increased hydration leads to body weight loss, mainly through a decrease in feeding, and a loss of fat, through increased lipolysis. The publications cited come from animal, mainly rodent, studies where manipulations of the central and/or the peripheral renin–angiotensin system lead to an increased drinking response and a decrease in body weight. This hypothesis derives from a broader association between chronic hypohydration (extracellular dehydration) and raised levels of the hormone angiotensin II (AngII) associated with many chronic diseases, such as obesity, diabetes, cancer, and cardiovascular disease. Proposed mechanisms to explain these effects involve an increase in metabolism due to hydration expanding cell volume. The results of these animal studies often can be applied to the humans. Human studies are consistent with this hypothesis for weight loss and for reducing the risk factors in the development of obesity and type 2 diabetes.

Discrete strategies to reduce intake of discretionary food choices: a scoping review

On a population level, dietary improvement strategies have had limited success in preventing the surge in overweight and obesity or reducing risk factors for chronic disease. While numerous multi-component studies have examined whole-of-diet strategies, and single component (i.e. discrete) dietary intervention strategies have targeted an increase in core foods (e.g. fruits, vegetables, dairy), there is a paucity of evidence on the effectiveness of dietary intervention strategies targeting a decrease in discretionary choices. The aim of this review was to identify dietary intervention strategies that are potentially relevant to reducing intake of discretionary choices in 2–65 year olds. A scoping review was carried out to map the literature on key discrete dietary intervention strategies that are potentially applicable to reducing discretionary choices, and to identify the targeted health/nutrition effects (e.g. improve nutrient intake, decrease sugar intake, and reduce body weight) of these strategies. Studies conducted in participants aged 2–65 years and published in English by July 20, 2015, were located through electronic searches including the Cochrane Library, Medline, Embase, CINAHL, and Scopus. Three thousand two hundred and eighty three studies were identified from the search, of which 44 met the selection criteria. The dietary intervention strategies included reformulation (n = 13), substitution (n = 5), restriction/elimination (n = 9), supplementation (n = 13), and nutrition education/messages (n = 4). The key findings of the review were: restricting portion size was consistently beneficial for reducing energy intake in the acute setting; reformulating foods from higher fat to lower fat could be useful to reduce saturated fat intake; substituting discretionary choices for high fibre snacks, fruit, or low/no-calorie beverages may be an effective strategy for reducing energy intake; supplementing nutrient dense foods such as nuts and wholegrain cereals supports an improved overall diet quality; and, a combination of permissive and restrictive nutrition messages may effectively modify behavior to reduce discretionary choices intake. Longer-term, well-controlled studies are required to assess the effectiveness of the identified dietary strategies as interventions to reduce discretionary choices intake.

Plain water consumption in relation to energy intake and diet quality among US adults, 2005-2012

OBJECTIVE

The present study examined plain water consumption in relation to energy intake and diet quality among US adults.

METHODS

A nationally representative sample of 18 311 adults aged ≥18 years, from the National Health and Nutrition Examination Survey 2005-2012, was analysed. The first-difference estimator approach addressed confounding bias from time-invariant unobservables (e.g. eating habits, taste preferences) by using within-individual variations in diet and plain water consumption between two nonconsecutive 24-h dietary recalls.

RESULTS

One percentage point increase in the proportion of daily plain water in total dietary water consumption was associated with a reduction in mean (95% confidence interval) daily total energy intake of 8.58 (7.87-9.29) kcal, energy intake from sugar-sweetened beverages of 1.43 (1.27-1.59) kcal, energy intake from discretionary foods of 0.88 (0.44-1.32) kcal, total fat intake of 0.21 (0.17-0.25) g, saturated fat intake of 0.07 (0.06-0.09) g, sugar intake of 0.74 (0.67-0.82) g, sodium intake of 9.80 (8.20-11.39) mg and cholesterol intake of 0.88 (0.64-1.13) g. The effects of plain water intake on diet were similar across race/ethnicity, education attainment, income level and body weight status, whereas they were larger among males and young/middle-aged adults than among females and older adults, respectively. Daily overall diet quality measured by the Healthy Eating Index-2010 was not found to be associated with the proportion of daily plain water in total dietary water consumption.

CONCLUSIONS

Promoting plain water intake could be a useful public health strategy for reducing energy and targeted nutrient consumption in US adults, which warrants confirmation in future controlled interventions.

The effects of water and dairy drinks on dietary patterns in overweight adolescents

The aim was to investigate the effects of increased water or dairy intake on total intake of energy, nutrients, foods and dietary patterns in overweight adolescents in the Milk Components and Metabolic Syndrome (MoMS) study (n=173). Participants were randomly assigned to consume 1l/d of skim milk, whey, casein or water for 12 weeks. A decrease in the dietary pattern called Convenience Food, identified by principal component analysis, was observed during the intervention both in the water and dairy groups. Total energy intake decreased by 990.9 kJ/d (236.8 kcal/d) in the water group but was unchanged in the dairy group during intervention. To conclude, an extra intake of fluid seems to favourably affect the rest of the diet by decreasing the intake of convenience foods, including sugar-sweetened beverages. A low energy drink, such as water, seems advantageous considering the total energy intake in these overweight adolescents. This study is registered at clinicaltrials.gov (NCT00785499).

Negative, Null and Beneficial Effects of Drinking Water on Energy Intake, Energy Expenditure, Fat Oxidation and Weight Change in Randomized Trials: A Qualitative Review

Drinking water has heterogeneous effects on energy intake (EI), energy expenditure (EE), fat oxidation (FO) and weight change in randomized controlled trials (RCTs) involving adults and/or children. The aim of this qualitative review of RCTs was to identify conditions associated with negative, null and beneficial effects of drinking water on EI, EE, FO and weight, to generate hypotheses about ways to optimize drinking water interventions for weight management. RCT conditions that are associated with negative or null effects of drinking water on EI, EE and/or FO in the short term are associated with negative or null effects on weight over the longer term. RCT conditions that are associated with lower EI, increased EE and/or increased FO in the short term are associated with less weight gain or greater weight loss over time. Drinking water instead of caloric beverages decreases EI when food intake is ad libitum. Drinking water increases EE in metabolically-inflexible, obese individuals. Drinking water increases FO when blood carbohydrate and/or insulin concentrations are not elevated and when it is consumed instead of caloric beverages or in volumes that alter hydration status. Further research is needed to confirm the observed associations and to determine if/what specific conditions optimize drinking water interventions for weight management.

Efficacy of water preloading before main meals as a strategy for weight loss in primary care patients with obesity: RCT

OBJECTIVE

To investigate the efficacy of water preloading before meals as a weight loss strategy for adults with obesity.

METHODS

A two-group randomized controlled trial was conducted in Birmingham, England. Eighty-four adults with obesity were recruited from general practices. All participants were given a face-to-face weight management consultation at baseline (30 min) and a follow-up telephone consultation at 2 weeks (10 min). At baseline, participants were randomized to either drinking 500 ml of water 30 min before their main meals or an attention control group where participants were asked to imagine their stomach was full before meals. The primary outcome was weight change at 12-week follow-up. Several measures of adherence were also used, including 24 h total urine collections.

RESULTS

41 participants were randomized to the intervention group and 43 to the comparator group. The water preloading group lost -1.3 kg (95% CI -2.4 to -0.1, P = 0.028) more than comparators at follow up. Adjusting for ethnicity, deprivation, age, and gender resulted in the intervention group losing -1.2 kg (95% CI -2.4 to 0.07, P = 0.063) more than the comparator.

CONCLUSIONS

There is preliminary evidence that water preloading before main meals leads to a moderate weight loss at follow up. ISRCTN33238158.

Gender and racial/ethnic background predict weight loss after Roux-en-Y gastric bypass independent of health and lifestyle behaviors

Our study investigated how demographic, health, and behavioral factors interacted to affect weight outcomes in bariatric patients. Roux-en-Y gastric bypass (RYGB) patients who were non-Hispanic black, Hispanic, or non-Hispanic white race/ethnicity, had no revisions to their RYGB during 2004-2009, and had at least 1 year of follow-up data for body weight after surgery (n = 860) were surveyed by phone about their health and behaviors. The main outcomes of interest were percent excess weight loss and percent of initial weight lost. Participants were 47 ± 11 years old, 54 % non-Hispanic white, 25 % Hispanic, and 21 % non-Hispanic black, 82 % female, 60 % married, 82 % had some college education, and 47 % had an annual income between $35,000 and $80,000. At the time of surgery, patients had lost 50 ± 29 % of their excess weight and had achieved 24 ± 15 % initial weight lost after an average of 54 months of follow-up. After accounting for weight at the time of surgery, demographics, and self-reported health and behavior, non-Hispanic black men had significantly greater weight loss compared to non-Hispanic white men (p < .05). There were no differences between racial/ethnic groups of women in weight outcomes. Percent excess weight loss was related to greater diet soda intake, and percent initial weight lost was related to greater water intake. Independent of health status and lifestyle behaviors, age, and weight at the time of surgery, race/ethnicity, gender, and diet soda and water intake were the strongest predictors of weight outcomes after RYGB surgery.

A Water and Education Provision Intervention Modifies the Diet in Overweight Mexican Women in a Randomized Controlled Trial

BACKGROUND

There is minimal information on the impact of replacing sugar-sweetened beverage (SSB) consumption with water on diet quality from randomized controlled trials.

OBJECTIVE

We evaluated the effect of a water intake intervention on diet quality in overweight Mexican women.

METHODS

Women with a body mass index ≥25 and <39, 18-45 y old, and a self-reported high intake of SSBs (≥250 kcal/d) were randomly allocated to either the water and education provision (WEP) group (n = 120) or the education provision (EP) only group (n = 120). Each group received monthly nutrition counseling, and the WEP group received biweekly water deliveries for 9 mo. Three 24-h recalls, anthropometry, and demographic information were collected at baseline, and 3, 6, and 9 mo. Energy, macronutrient, sugar, SSB, fruit and vegetable, salty snack, cake and cookie, and fast food intakes were assessed in study completers (n = 189) classified by intervention assignment and by actual water intake at every time point (low <1200 vs. high ≥1200 mL/d).

RESULTS

The WEP group reported greater decreases in SSB intake than the EP group (from 20.9% to 10.3% of energy/d vs. from 20.1% to 17.8%). Thirty-eight percent of the EP group and 84.3% of the WEP group reported attaining a water intake ≥1200 mL/d. Reductions in energy intake and food groups were similar across intervention groups. However, the high actual water intake group reported greater increases vs. the lower intake group in intake of fruits and vegetables (117 vs. 47 g/d), as well as larger reductions in salty snacks (4.6 vs. 0.7 g/d) and cakes and cookies (31.7 vs. 14.7 g/d).

CONCLUSIONS

Other than SSBs, improvements in food group intake did not differ by intervention group in overweight Mexican women. However, post hoc analyses suggested that achieving a high actual water intake was associated with additional beneficial changes in food group intake. This trial was registered at clinicaltrials.gov as NCT01245010.

Critical review and rethinking of USEPA secondary standards for maintaining organoleptic quality of drinking water

Consumers assess their tap water primarily by its taste, odor, and appearance. Starting in 1979, USEPA promulgated Secondary Maximum Contaminant Levels (SMCLs) as guidance for contaminants with organoleptic effects and also to maintain consumers’ confidence in tap water. This review assesses the basis for the 15 SMCLs (aluminum, chloride, color, copper, corrosivity, fluoride, foaming agents, iron, manganese, odor, pH, silver, sulfate, total dissolved solids, zinc) and summarizes advances in scientific knowledge since their promulgation. SMCLs for aluminum, color, pH, silver, sulfate, total dissolved solids, and zinc are appropriate at current values and remain consistent with sensory science literature. Recent advances in sensory and health sciences indicate that SMCLs for chloride, copper, fluoride, iron, and manganese are too high to minimize organoleptic effects. The SMCLs for corrosivity and foaming agents may be outdated. The SMCL for odor requires rethinking as the test does not correlate with consumer complaints. Since current stresses on source and treated waters include chemical spills, algal blooms, and increased salinization, organoleptic episodes that negatively impact consumer confidence and perception of tap water still occur and may increase. Thus, adherence to SMCLs can help maintain production of palatable water along with consumers’ confidence in their water providers.

Weighing the Evidence of Common Beliefs in Obesity Research

Obesity is a topic on which many views are strongly held in the absence of scientific evidence to support those views, and some views are strongly held despite evidence to contradict those views. We refer to the former as "presumptions" and the latter as "myths." Here, we present nine myths and 10 presumptions surrounding the effects of rapid weight loss; setting realistic goals in weight loss therapy; stage of change or readiness to lose weight; physical education classes; breastfeeding; daily self-weighing; genetic contribution to obesity; the "Freshman 15"; food deserts; regularly eating (versus skipping) breakfast; eating close to bedtime; eating more fruits and vegetables; weight cycling (i.e., yo-yo dieting); snacking; built environment; reducing screen time in childhood obesity; portion size; participation in family mealtime; and drinking water as a means of weight loss. For each of these, we describe the belief and present evidence that the belief is widely held or stated, reasons to support the conjecture that the belief might be true, evidence to directly support or refute the belief, and findings from randomized controlled trials, if available. We conclude with a discussion of the implications of these determinations, conjecture on why so many myths and presumptions exist, and suggestions for limiting the spread of these and other unsubstantiated beliefs about the obesity domain.

Beyond the role of dietary protein and amino acids in the prevention of diet-induced obesity

High-protein diets have been shown to prevent the development of diet-induced obesity and can improve associated metabolic disorders in mice. Dietary leucine supplementation can partially mimic this effect. However, the molecular mechanisms triggering these preventive effects remain to be satisfactorily explained. Here we review studies showing a connection between high protein or total amino nitrogen intake and obligatory water intake. High amino nitrogen intake may possibly lower lipid storage, and prevent insulin resistance. Suggestions are made for further systematical studies to explore the relationship between water consumption, satiety, and energy expenditure. Moreover, these examinations should better distinguish between leucine-specific and unspecific effects. Research in this field can provide important information to justify dietary recommendations and strategies in promoting long-term weight loss and may help to reduce health problems associated with the comorbidities of obesity.

The Hydration Equation: Update on Water Balance and Cognitive Performance

To become aware of the most practical measures of hydration status.To describe sources of water input and output and the basics of water balance.To understand how hydration status may impact daily cognitive performance.

CONDENSED VERSION AND BOTTOM LINE

Water is a crucial nutrient and euhydration is necessary for optimal daily functioning. Water balance is precisely regulated within the body and many methods exist for assessing hydration status. Cognitive performance measures an individual's attentiveness, critical thinking skills, and memory. Traditionally a 2% or more body water deficit was thought to produce cognitive performance decrements; however, recent literature suggests that even mild dehydration - a body water loss of 1-2% - can impair cognitive performance. Counseling clients about their health and wellbeing should include conveying the importance of water for normal body functioning, as well as its effects on physical and cognitive performance.

Changes in water and beverage intake and long-term weight changes: results from three prospective cohort studies

OBJECTIVE

To examine the long-term relationship between changes in water and beverage intake and weight change.

SUBJECTS

Prospective cohort studies of 50013 women aged 40-64 years in the Nurses' Health Study (NHS, 1986-2006), 52987 women aged 27-44 years in the NHS II (1991-2007) and 21988 men aged 40-64 years in the Health Professionals Follow-up Study (1986-2006) without obesity and chronic diseases at baseline.

MEASURES

We assessed the association of weight change within each 4-year interval, with changes in beverage intakes and other lifestyle behaviors during the same period. Multivariate linear regression with robust variance and accounting for within-person repeated measures were used to evaluate the association. Results across the three cohorts were pooled by an inverse-variance-weighted meta-analysis.

RESULTS

Participants gained an average of 1.45 kg (5th to 95th percentile: -1.87 to 5.46) within each 4-year period. After controlling for age, baseline body mass index and changes in other lifestyle behaviors (diet, smoking habits, exercise, alcohol, sleep duration, TV watching), each 1 cup per day increment of water intake was inversely associated with weight gain within each 4-year period (-0.13 kg; 95% confidence interval (CI): -0.17 to -0.08). The associations for other beverages were: sugar-sweetened beverages (SSBs) (0.36 kg; 95% CI: 0.24-0.48), fruit juice (0.22 kg; 95% CI: 0.15-0.28), coffee (-0.14 kg; 95% CI: -0.19 to -0.09), tea (-0.03 kg; 95% CI: -0.05 to -0.01), diet beverages (-0.10 kg; 95% CI: -0.14 to -0.06), low-fat milk (0.02 kg; 95% CI: -0.04 to 0.09) and whole milk (0.02 kg; 95% CI: -0.06 to 0.10). We estimated that replacement of 1 serving per day of SSBs by 1 cup per day of water was associated with 0.49 kg (95% CI: 0.32-0.65) less weight gain over each 4-year period, and the replacement estimate of fruit juices by water was 0.35 kg (95% CI: 0.23-0.46). Substitution of SSBs or fruit juices by other beverages (coffee, tea, diet beverages, low-fat and whole milk) were all significantly and inversely associated with weight gain.

CONCLUSION

Our results suggest that increasing water intake in place of SSBs or fruit juices is associated with lower long-term weight gain.

Challenges of linking chronic dehydration and fluid consumption to health outcomes

The purpose of this article is to review the effects of chronic mild dehydration and fluid consumption on specific health outcomes including obesity. The electronic databases PubMed and Google Scholar were searched for relevant literature published from the time of their inception to 2011, with results restricted to studies performed on human subjects and reports in the English language. Key words included the following: dehydration, hypohydration, water intake, fluid intake, disease, and the names of specific disease states. Strength of evidence categories were described for 1) medical conditions associated with chronic dehydration or low daily water intake, and 2) randomized-controlled trials regarding the effects of increased water consumption on caloric intake, weight gain, and satiety. This process determined that urolithiasis is the only disorder that has been consistently associated (i.e., 11 of 13 publications) with chronic low daily water intake. Regarding obesity and type 2 diabetes, evidence suggests that increased water intake may reduce caloric intake for some individuals. Recommendations for future investigations include measuring total fluid intake (water + beverages + water in solid food), conducting randomized-controlled experiments, identifying novel hydration biomarkers, and delineating hydration categories.

Water and sugar-sweetened beverage consumption and changes in BMI among Brazilian fourth graders after 1-year follow-up

Objective

We examined whether drinking water per se is associated with drinking less of other beverages and whether changes in BMI are associated with the intake of water and other beverages.

Design

Secondary analysis of a randomized trial of fourth graders followed over 1 year.

Setting

Public schools in the metropolitan area of Rio de Janeiro, Brazil.

Subjects

Participants were 1134 students aged 10–11 years.

Results

At baseline, a higher frequency of water consumption was associated with a greater daily intake of fruit juice (P = 0·02) and a higher daily frequency of milk (P = 0·005). In the intervention group, the baseline frequency of water consumption was negatively associated with weight change over 1 year but without statistical significance (coefficient = −0·08 kg/m2; 95 % CI −0·37, 0·24 kg/m2), whereas fruit juice intake frequency was positively associated with weight change: each increase in fruit juice intake of 1 glass/d was associated with a BMI increase of 0·16 (95 % CI 0·02, 0·30) kg/m2.

Conclusions

Our findings do not support a protective effect of water consumption on BMI, but confirm consumption of juice drinks as a risk factor for BMI gain. Students who reported high water consumption also reported high intake of other beverages; therefore, the promotion of water consumption per se would not prevent excessive weight gain.

Daily self-monitoring of body weight, step count, fruit/vegetable intake, and water consumption: a feasible and effective long-term weight loss maintenance approach

Maintenance of weight loss remains a challenge for most individuals. Thus, practical and effective weight-loss maintenance (WTLM) strategies are needed. A two-group 12-month WTLM intervention trial was conducted from June 2007 to February 2010 to determine the feasibility and effectiveness of a WTLM intervention for older adults using daily self-monitoring of body weight, step count, fruit/vegetable (F/V) intake, and water consumption. Forty weight-reduced individuals (mean weight lost=6.7±0.6 kg; body mass index [calculated as kg/m²] 29.2±1.1), age 63±1 years, who had previously participated in a 12-week randomized controlled weight-loss intervention trial, were instructed to record daily body weight, step count, and F/V intake (WEV [defined as weight, exercise, and F/V]). Experimental group (WEV+) participants were also instructed to consume 16 fl oz of water before each main meal (ie, three times daily), and to record daily water intake. Outcome measures included weight change, diet/physical activity behaviors, theoretical constructs related to health behaviors, and other clinical measures. Statistical analyses included growth curve analyses and repeated measures analysis of variance. Over 12 months, there was a linear decrease in weight (β=-0.32, P<0.001) and a quadratic trend (β=0.02, P<0.01) over time, but no group difference (β=-0.23, P=0.08). Analysis of the 365 days of self-reported body weight for each participant determined that weight loss was greater over the study period in the WEV+ group than in the WEV group, corresponding to weight changes of -0.67 kg and 1.00 kg, respectively, and an 87% greater weight loss (β=-0.01, P<0.01). Overall compliance to daily tracking was 76%±5%. Daily self-monitoring of weight, physical activity, and F/V consumption is a feasible and effective approach for maintaining weight loss for 12 months, and daily self-monitoring of increased water consumption may provide additional WTLM benefits.

Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial

BACKGROUND

Replacement of caloric beverages with noncaloric beverages may be a simple strategy for promoting modest weight reduction; however, the effectiveness of this strategy is not known.

OBJECTIVE

We compared the replacement of caloric beverages with water or diet beverages (DBs) as a method of weight loss over 6 mo in adults and attention controls (ACs).

DESIGN

Overweight and obese adults [n = 318; BMI (in kg/m(2)): 36.3 ± 5.9; 84% female; age (mean ± SD): 42 ± 10.7 y; 54% black] substituted noncaloric beverages (water or DBs) for caloric beverages (≥200 kcal/d) or made dietary changes of their choosing (AC) for 6 mo.

RESULTS

In an intent-to-treat analysis, a significant reduction in weight and waist circumference and an improvement in systolic blood pressure were observed from 0 to 6 mo.Mean ((±SEM) weight losses at 6 mo were -2.5 ± 0.45% in the DB group, -2.03 ± 0.40% in the water group, and -1.76 ± 0.35% in the AC group; there were no significant differences between groups [corrected]. The chance of achieving a 5% weight loss at 6 mo was greater in the DB group than in the AC group (OR: 2.29; 95% CI: 1.05, 5.01; P = 0.04). A significant reduction in fasting glucose at 6 mo (P = 0.019) and improved hydration at 3 (P = 0.0017) and 6 (P = 0.049) mo was observed in the Water group relative to the AC group. In a combined analysis, participants assigned to beverage replacement were 2 times as likely to have achieved a 5% weight loss (OR: 2.07; 95% CI: 1.02, 4.22; P = 0.04) than were the AC participants.

CONCLUSIONS

Replacement of caloric beverages with noncaloric beverages as a weight-loss strategy resulted in average weight losses of 2% to 2.5%. This strategy could have public health significance and is a simple, straightforward message. This trial was registered at clinicaltrials.gov as NCT01017783.

Effect of Mediterranean diet on lipid peroxidation marker TBARS in obese patients with OSAHS under CPAP treatment: a randomised trial

PURPOSE

The aim of our study was to examine the possible effect of the Mediterranean diet on thiobarbituric acid reacting substances (TBARS) in obese patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) who are under continuous positive airway pressure treatment.

METHODS

Nine hundred patients were evaluated during a 1-year period (November 2008-October 2009), and 21 obese patients who met the inclusion criteria, with moderate to severe OSAHS based on overnight attended polysomnography, were included in the study. After randomisation, 11 followed the Mediterranean diet and 10 a prudent diet for a 6-month period. TBARS were measured in serum.

RESULTS

TBARS levels decreased notably in both groups (p < 0.05), but no difference was observed between them (p > 0.05). There were significant differences in other characteristics. The Mediterranean diet group showed a greater reduction in weight (-10.8 ± 3.8), body mass index (-3.9 ± 1.6), waist circumference (-9.9 ± 3.0) and percentage of body fat (-4.7 ± 2.3) compared with the other group (-6.9 ± 3.1, -2.5 ± 1.0, -5.3 ± 2.6 and -2.2 ± 1.5, respectively; p < 0.05).

CONCLUSIONS

Our results showed that the Mediterranean diet did not reduce the TBARS more than the prudent diet.

Satiety: have we neglected dietary non-nutrients?

Satiety, which is the inhibition of eating following the end of a meal, is influenced by a number of food characteristics, including compositional and structural factors. An increased understanding of these factors and the mechanisms whereby they exert their effects on satiety may offer a food-based approach to weight management. Water and gas, which are often neglected in nutrition, are major components of many foods and contribute to volume, and to sensory and other characteristics. A review of previous short-term studies that evaluated the effects of water or gas in foods on satiety showed that while satiety was generally increased, effects on subsequent intakes were not always apparent. These studies were diverse in terms of design, timings and food matrices, which precludes definitive conclusions. However, the results indicate that solids may be more effective at increasing satiety than liquids, but gas may be as effective as water. Although increased gastric distension may be the main mechanism underlying these effects, pre-ingestive and ingestive impacts on cognitive, anticipatory and sensory responses also appear to be involved. Furthermore, there is limited evidence that water on its own may be effective at increasing satiety and decreasing intakes when drunk before, but not with, a meal. Longer-term extrapolation suggests that increasing food volumes with water or gas may offer weight-management strategies. However, from a practical viewpoint, the effects of water and gas on satiety may be best exploited by using these non-nutrients to manipulate perceived portion sizes, without increasing energy contents.