Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle-aged and Older Adults

Transcription

1 nture publishing group Wter Consumption Increses Weight Loss During Hypocloric Diet Intervention in Middle-ged nd Older Adults Elizbeth A. Dennis 1, An Lur Dengo 1, Dn L. Comber 1, Kyle D. Flck 2, Jyoti Svl 3, Kevin P. Dvy 1 nd Brend M. Dvy 1 Wter consumption cutely reduces mel energy intke (EI) mong middle-ged nd older dults. Our objectives were to determine if premel wter consumption fcilittes weight loss mong overweight/obese middle-ged nd older dults, nd to determine if the bility of premel wter consumption to reduce mel EI is sustined fter 12-week period of incresed wter consumption. Adults (n = 48; yers, BMI 25 kg/m 2 ) were ssigned to one of two groups: (i) hypocloric diet + 5 ml wter prior to ech dily mel (wter group), or (ii) hypocloric diet lone (nonwter group). At bseline nd week 12, ech prticipnt underwent two d libitum test mels: (i) no prelod (NP), nd (ii) 5 ml wter prelod (WP). Mel EI ws ssessed t ech test mel nd body weight ws ssessed weekly for 12 weeks. Weight loss ws ~2 kg greter in the wter group thn in the nonwter group, nd the wter group (β =.87, P <.1) showed 44% greter decline in weight over the 12 weeks thn the nonwter group (β =.6, P <.1). Test mel EI ws lower in the WP thn NP condition t bseline, but not t week 12 (bseline: WP 498 ± 25 kcl, NP 541 ± 27 kcl, P =.9; 12-week: WP 48 ± 25 kcl, NP 56 ± 25 kcl, P =.69). Thus, when combined with hypocloric diet, consuming 5 ml wter prior to ech min mel leds to greter weight loss thn hypocloric diet lone in middle-ged nd older dults. This my be due in prt to n cute reduction in mel EI following wter ingestion. Obesity (1) 18, doi:1.138/oby Introduction If recent trends continue, 86% of US dults will be overweight or obese by the yer 3 (1). Middle-ged nd older dults (ged yers) re t incresed risk for obesity nd ~7% in this segment of the popultion re currently overweight or obese (2). Age-relted weight gin my be ttributed to severl fctors including reduction in energy expenditure, reduction in energy requirements, nd n incresed susceptibility to energy overconsumption (3 6). Obesity mong older dults is ssocited with impired physicl function, incresed morbidity nd mortlity, nd greter helth cre costs (7 9). Thus, identifying successful weight mngement strtegies for middle-ged nd older dults hs significnt public helth implictions. Incresing dily wter consumption is widely recognized s weight loss strtegy in the generl public, yet there is surprisingly little dt supporting this prctice. Epidemiologicl studies suggest tht energy intke (EI) is significntly lower (~9%, or 194 kcl/d) in wter drinkers compred with nonwter drinkers (1), nd tht sweetened beverge consumption is ssocited with weight gin nd obesity (11). Recently, investigtors reported tht substituting wter for energy-contining beverges decreses self-reported EI (12), nd tht incresing self-reported dily wter consumption by 1 l in overweight women is ssocited with incresed weight loss of ~2 kg over 12-month diet intervention compred with women who consumed <1l wter dily (13). Lbortory-bsed test mel studies hve demonstrted tht wter consumed with mel reduces rtings of hunger nd increses rting of stiety (14,15), though no differences in mel EI were observed when compred to no beverge condition (14). We (16,17) hve recently demonstrted tht both norml-weight nd overweight/obese middleged nd older dults ingest less energy t n d libitum mel when given wter prelod (WP) (5 ml, ~16 fl oz) 3 min prior to the mel compred with no-prelod mel condition. However, reduction in mel EI following wter ingestion hs not been observed in studies of young dults (16,18), suggesting there my be ge-relted differences in the bility of wter 1 Deprtment of Humn Nutrition, Foods nd Exercise, Virgini Tech, Blcksburg, Virgini, USA; 2 Deprtment of Helth Sciences, Ferrum College, Ferrum, Virgini, USA; 3 Deprtment of Humn Development nd Center for Gerontology, Virgini Tech, Blcksburg, Virgini, USA. Correspondence: Brend M. Dvy (bdvy@vt.edu) Received 22 December 8; ccepted 14 June 9; published online 6 August 9. doi:1.138/oby VOLUME 18 NUMBER 2 februry 1

2 to cutely reduce EI. Other studies reporting no effect of wter ingestion on EI in young dults (19 21) hve used wter s control condition; no-prelod condition is not vilble for comprison. It is unknown if incresed wter consumption fcilittes weight loss over time. We tested the hypothesis tht premel wter consumption would led to greter weight loss in older overweight nd obese individuls consuming hypocloric diet. Given previous findings (16,17), secondry objective ws to determine if the bility of premel wter consumption to reduce d libitum EI is sustined fter 12-week period of incresed wter consumption in older overweight nd obese dults. Methods nd Procedures Subject ch rcteristics Overweight or obese (BMI 25 kg/m 2 ) men nd women between the ges of yers were recruited from the locl community though newspper dvertisements. For inclusion in the study, individuls were required to be weight stble (± 2 kg, >1 yer) nd nonsmokers. Individuls were excluded if they reported history of depression, eting disorders, dibetes, uncontrolled hypertension (>159/99 mm Hg), hert, lung, kidney disese; cncer, food llergies/ intolernces to items used in the lbortory test mels; or current use of medictions known to lter food intke or body weight. Individuls were blinded to the specific purpose of the study, nd were informed tht the study involved exmintion of dietry fctors believed to influence weight loss. The study protocol ws pproved by the Institutionl Review Bord of Virgini Polytechnic Institute nd Stte University. All prticipnts provided written informed consent prior to study enrollment. Protocol Initil screening procedures nd bseline ssessments. An overview of the study protocol is depicted in Figure 1. Individuls meeting initil enrollment criteri completed bseline lbortory ssessments over series of four visits. Height ws mesured in meters without shoes using wll-mounted stdiometer, nd body weight ws mesured to the nerest.1 kg using digitl scle with prticipnts wering light street clothing nd no shoes (Scle-Tronix model 52, Wheton, IL). Percentge body ft, bsolute ft mss, ft-free mss, nd totl body bone minerl content were mesured using dul-energy X-ry bsorptiometry (GE Lunr Prodigy; GE Helthcre, Mdison, WI). Wist circumference ws mesured to the nerest.5 cm t the umbilicus, using Gulick tpe mesure (Gulick, Country Technology, Gys Mill, WI). Resting blood pressure ws mesured in the seted position using mercury sphygmomnometer fter 15-min period of rest; the verge of three mesurements ±6 mm Hg ws used. To ssess hbitul dietry intke nd beverge consumption, prticipnts were instructed in proper methods to record their food nd beverge intke (including wter consumption) for 4 consecutive dys, which included 3 weekdys nd 1 weekend dy, nd provided with food models to ssist in portion size determintion. Records were reviewed for completeness upon their return, nd nlyzed using diet nlysis softwre (NDS-R Individuls ssessed for eligibility (n = 65) Initil screening tests Visit 1: Medicl history, eting hbits nd depression questionnires, 4-dy food record, 4-dy ctivity monitor Visit 2: Fsting blood drw, body composition, blood pressure Visit 3: Lbortory d libitum test mel 1 Visit 4: Lbortory d libitum test mel 2 Excluded (n = 17) Did not meet inclusion criteri (n = 8) Refused to prticipte (n = 9) Rndomized (n = 48) Hypocloric diet + incresed wter consumption (n = 23) wter group Discontinued intervention (n = 2) Time constrints 12-Week intervention Weekly body weight checks, diet counseling Urine collection nd food records t weeks 4, 8 Hypocloric diet lone (n = 25) nonwter group Discontinued intervention (n = 4) Lost interest (n = 3) Trnsporttion problems (n = 1) 12-Week post-testing Visit 17: Fsting blood drw, body composition, 4 dy food record, 24-h urine collection, 4 dy physicl ctivity monitor, exit surveys Visit 18: Lbortory d libitum test Mel 3 Visit 19: Lbortory d libitum test Mel 4 Follow-up 12-Week post-testing Visit 17: Fsting blood drw, body composition, 4 dy food record, 24-h urine collection, 4 dy physicl ctivity monitor, exit surveys Visit 18: Lbortory d libitum test Mel 3 Visit 19: Lbortory d libitum test Mel 4 Included in nlysis (n = ) Incomplete post dt (n = 1) Anlysis Included in nlysis (n = 21) Figure 1 Study design. obesity VOLUME 18 NUMBER 2 februry 1 31

3 4.5; University of Minnesot, Minnepolis, MN). A second trined technicin reviewed ll diet nlyses for dt entry errors. To ssess hbitul beverge consumption, bseline nd week 12 food intke records were mnully reviewed to clculte men dily mounts (kcl, g) of wter nd other beverges consumed. Dietry energy density (ED; kcl/g) ws clculted from the food nd beverge intke records nd ws expressed in four wys (22): totl ED including ll foods nd beverges consumed; beverge ED including wter; beverge ED excluding wter; nd ED from food only, excluding ll beverges. When compring ED (food + beverges) between individuls or over time, excluding wter from the clcultion could led to higher ED vlues mong wter consumers or those incresing wter intke, compred to those consuming energy-free beverges (diet sods, coffee, nd te) (22). Thus, multiple ED clcultions were performed. Prticipnts collected urine for one 24-h period for ssessment of totl urine volume, nd specific grvity ws determined using refrctometer (Fisher UriSystem; Fisher Scientific, Hmpton, NH). Blood ws smpled from n ntecubitl vein for ssessment of lipid nd lipoprotein concentrtions, which were performed using SynchronLX (Beckmn Coulter, Fullerton, CA). Totl cholesterol nd triglyceride concentrtions were determined using the timed endpoint method, high-density lipoprotein cholesterol ws determined by homogenous ssy, nd low-density lipoprotein cholesterol ws determined by clcultion. Hbitul physicl ctivity (steps/dy) ws mesured using GT1M ctivity monitors for 4-dy period (ActiGrph, Penscol, FL). Following initil ssessments, ech prticipnt underwent two lbortory test mel conditions within 2-week period, seprted by minimum of 2 dys, in rndom order s follows: (i) 3-min witing period (no prelod (NP)) followed by n d libitum brekfst mel, nd (ii) prelod consisting of 5 ml (~16 fl oz) chilled bottled wter followed within 3 min by n d-lib mel. Condition 1 served s the bseline EI for comprison. A 3-min time intervl between the prelod nd d libitum mel is the most effective time intervl to study EI compenstion using prelods (23). Subjects were instructed not to et or drink for t lest 12 h prior to rriving for the test mel. The mel consisted of typicl brekfst items (cinnmon risin bgel, crem cheese, mrgrine, jelly, vnill yogurt, bnn, mozzrell cheese stick, cerel br, ornge juice, coffee, crem, nd sugr) provided in excess of wht would normlly be consumed, from which the prticipnts were llowed to self-select during -min mel period. All foods used in the brekfst mels were evluted for pltbility prior to study initition. Foods were presented on mel try nd rrnged in the sme mnner (i.e., loction on try, temperture) on both testing dys, nd mels were served in individuls cubicles under stndrdized lbortory conditions (i.e., quiet, temperture controlled). All foods were covertly weighed (±.1 g) before being served nd gin fter the completion of the mel to determine the mount consumed. Mel energy nd nutrient intke were clculted using diet nlysis softwre (NDS-R; University of Minnesot, Minnepolis, MN). Prticipnts completed visul nlog scles during the test mel procedure t times, 3, 6, 9, 1, nd 15 min to subjectively rte their feelings of hunger, stiety (fullness) nd thirst (24 26). Time represented rrivl for the mel nd time 3 represented the time immeditely prior to receiving the mel. Intervention period. Following completion of ll bseline ssessments (Figure 1), prticipnts were rndomly ssigned to one of two diet groups for 12 weeks: (i) hypocloric diet + 16 fl oz (5 ml) bottled wter prior to ech of the three dily mels ( wter group ), or (ii) hypocloric diet lone ( nonwter group ). Individuls ssigned to the wter group were provided with cses of bottled wter (Aqufin; Pepsico, Purchse, NY), nd were instructed to consume one bottle prior to ech mel (3 16 fl oz bottles/dy). Wter group prticipnts were provided with dily trcking form to record their premel wter consumption, which ws returned to the study personnel t weekly visits for clcultion of weekly wter consumption (%) complince. Nonwter group prticipnts were offered bottled wter, but were not given instructions or recommendtions on wter consumption. Both groups were provided with vriety of dditionl foods consistent with their mel plns, in order to keep prticipnts blinded to the study purpose. Consumption of these items ws not mndtory. Prticipnts received one provided food per week in ddition to the bottled wter, nd ll prticipnts received the sme food item during tht week (e.g., seven red delicious pples, 55 kcl ech; seven nvel ornges, 62 kcl ech; one box of microwve popcorn, Orville Redenbcher s Smrt Pop 94% Ft-Free, four Butter-Flvored 1-clorie pcks; ConAgr Foods, Omh, NE). Both groups received individulized instruction by registered dietitin on hypocloric diet (women: 1, kcl, men: 1,5 kcl), which ws developed using United Sttes Deprtment of Agriculture food guide pyrmid guidelines (27). Consumption of fruits, vegetbles, len sources of protein, lowft/nonft diry products, nd whole grins ws emphsized; both groups were instructed to moderte their consumption of high-ft snck foods, sweetened energy-contining beverges, nd lcohol. Mel pln booklets with smple menus were lso provided. Averge energy nd mcronutrient content (% energy from ft/crbohydrte/protein, ED) of the 1, nd 1,5 kcl smple menus, not including optionl energy-free beverges (e.g., wter, diet soft drinks) were s follows: 1,191 kcl (3/52/21, 1.28 kcl/g); 1,425 kcl (28/53/22,.93 kcl/g). Prticipnts were instructed to mintin their current level of physicl ctivity throughout the intervention. Prticipnts returned weekly to the lbortory for body weight mesurement nd dietry counseling, nd dietry intke records were repeted t weeks 4 nd 8 to encourge complince. Post-testing. Following the 12-week intervention, prticipnts repeted ll bseline mesurements (body weight nd composition, 4-dy dietry intke record nd ctivity monitoring, fsting blood drw, resting blood pressure, 24-h urine collection, two d libitum lbortory test mel studies), completed n exit survey, nd were compensted $5. Sttisticl nlyses Power clcultions (α =.5, power =.8) were performed bsed upon expected differences in weight loss between hypocloric diets groups (2. ± 2.5 kg) to determine the trgeted finl smple size (n = ). Bseline group demogrphic chrcteristics were ssessed using independent smples t-test nd Person s χ 2 -tests (SPSS vs. 12. for windows). To ssess group difference in weight loss over 12 weeks, rndom coefficients (mixed) model (i.e., growth curve nlysis) ws used, which includes ll vilble dt from n individul, corrects for unrelibility of mesurement nd emphsizes individul growth trjectories rther thn verge vlues t ech occsion (28,29). The growth curve model ws fitted using STATA 9.1 xtmixed function. Fullinformtion mximum likelihood estimtion, which uses ll vilble dt (i.e., weekly body weight mesurements) on the 48 prticipnts enrolled into the intervention, ws used to ddress prtilly observed dt. To cpture potentil vritions in the effect of incresed wter consumption on weight loss over the 12-week intervention, qudrtic effect of time (week-squred) ws included in the model s covrite. The intercept ws specified t the first occsion of mesurement (i.e., week = ). Follow-up occsions occurred weekly for 12 weeks, nd time ws coded s 12. All min effects nd their interctions with the liner nd qudrtic effects remined in the model regrdless of the significnce of the effect. For secondry outcome vribles, repeted mesures ANOVA ws used to ssess group nd time differences for subjects completing the 12-week intervention; nlysis of covrince ws used to djust for bseline differences when present. When significnt interctions were detected, t-tests were used for post hoc nlyses. Group differences in pre-to-post chnge vlues (Δ) were nlyzed using independent smples t-test. The trpezoidl model ws used to clculte re under the curve (AUC) for ech visul nlog scle vrible (3), nd differences in visul nlog scle rtings during the test mel period were ssessed using repeted mesures ANOVA. Associtions mong vribles were ssessed by simple correltionl nlyses (Person s r). The α-level ws set priori t P <.5. Dt re expressed s men ± s.e.m. 32 VOLUME 18 NUMBER 2 februry 1

4 Results Bseline chrcteristics In the study, 48 individuls were enrolled nd rndomized, nd 41 completed the 12-week intervention nd ll post-testing mesurements (Figure 1). Bseline group demogrphic chrcteristics re shown in Tble 1. Most prticipnts were white (~92%), nd remining prticipnts were Africn Americn (n = 2), nd other (n = 2). There were no group differences t bseline in ge, body weight, BMI, body composition, urinry specific grvity, systolic blood pressure, totl cholesterol nd triglyceride concentrtion, or physicl ctivity level; however, 24-h urine volume nd high-density lipoprotein cholesterol concentrtion ws lower nd distolic blood pressure nd lowdensity lipoprotein cholesterol concentrtion ws higher in the wter group t bseline (Tble 2). There were no bseline Tble 1 Bseline group demogrphic chrcteristics: hypocloric diet with incresed dily wter consumption ( wter group ) nd hypocloric diet lone ( nonwter group ) Wter group (n = 23) Nonwter group (n = 25) Men/women, n 12/11 6/19 Rce, white/nonwhite, n 21/2 23/2 Age, yers 62.6 ± ± 1. Height, m 1.69 ± ±.2 Weight, kg 93.2 ± ± 3.4 BMI, kg/m ± ± 1.3 Dt re presented s men ± s.e.m. Group difference, P <.5. group differences in men dily intke of wter, totl beverge volume, or beverge energy content (Tble 3). Intervention As depicted in Figure 2, weight declined significntly over the 12 weeks for both groups (β =.27, P <.1), lthough the wter group (β =.87, P <.1) showed 44% greter decline (i.e., greter rte of weight loss) over the 12 weeks thn the nonwter group (β =.6, P <.1). There ws lso significnt qudrtic trend in weight loss (β =.1, P <.5), indicting tht the liner decline in weight leveled off towrd the end of the study period. This btement ws greter for the wter group (β =.3, P <.1) thn for the nonwter group (β =.2, P <.1). Body composition nd other clinicl outcome vribles t bseline nd postintervention re presented in Tble 2. Decline in totl ft mss ws greter in the wter thn nonwter group (wter: Δ 5.4 ±.6 kg; nonwter: Δ 3.3 ±.5 kg; P =.1); however, percent of initil body weight lost (7.8 ±.7% vs. 6.5 ±.7%, wter vs. nonwter, respectively; P =.17) nd reduction in percent body ft (wter: Δ 3.4 ±.5%; nonwter: Δ 2.1 ±.6%; P =.8) were not different between groups. Reductions in BMI, wist circumference, systolic nd distolic blood pressure, totl cholesterol, low-density lipoprotein cholesterol, nd triglyceride concentrtions were observed over the 12-week intervention, but there were no group differences in chnges in these outcomes (Tble 2). There ws no chnge over time or between groups in bone minerl content during the 12-week intervention. The reduction in high-density lipoprotein cholesterol concentrtion ws smller in the wter group compred with the nonwter group following the Tble 2 Body composition nd other clinicl chrcteristics in the wter nd nonwter groups before nd fter the 12-week intervention Wter group Nonwter group Bseline Week 12 Bseline Week 12 BMI, kg/m ± ± ± ± 1.1 Wist circumference, cm 15.5 ± ± ± ± 2.6 % Body ft 39.9 ± ± ± ± 1.9 Totl ft mss, kg b 35.1 ± ± ± ± 2.2 Totl ft-free mss, kg 52.4 ± ± ± ± 2.5 Totl bone minerl content, kg 3.1 ± ± ± ±.1 Systolic blood pressure, mm Hg 126 ± ± 2 1 ± ± 2 Distolic blood pressure, mm Hg,c 8 ± 1 73 ± 1 74 ± 1 69 ± 1 Totl cholesterol, mg/dl 221 ± ± ± ± 7.9 HDL-C, mg/dl b,c 42 ± ± ± ± 2.6 LDL-C, mg/dl 153 ± ± ± ± 6.6 Triglycerides, mg/dl d 132 ± ± ± ± 15.3 Urine volume, ml,c 1,594 ± 171 2,233 ± 168 1,951 ± 153 2,214 ± 15 Specific grvity, UG b 1.15 ± ± ± ±.1 Dt re presented s men ± s.e.m. Significnt min effect of time, P <.1. b Significnt group by time interction, P <.5. c Group difference t bseline, P <.5. d Significnt min effect of time, P <.5. obesity VOLUME 18 NUMBER 2 februry 1 33

5 Tble 3 Self-reported dietry intke nd physicl ctivity in wter nd nonwter groups before nd fter the 12-week intervention Totl diet Wter group Nonwter group Bseline Week 12 Bseline Week 12 Energy, kcl/d 1,991 ± 131 1,454 ± 95 2,85 ± 134 1,511 ± 98 Weight, g/d b 2,616 ± 148 3,226 ± 228 2,884 ± 152 2,699 ± 234 Crbohydrte (% energy) 48.5 ± ± ± ± 2.7 Protein (% energy) 16.1 ± ± ± ±.6 Ft (% energy) 35.2 ± ± ± ± 2.1 Energy density, kcl/g cd.78 ±.5.48 ±.5.74 ±.5.63 ±.5 Beverges only Energy, kcl/d 235 ± ± ± ± 25 Weight, g/d b 1,588 ± 121 2,287 ± 157 1,762 ± 124 1,372 ± 161 Wter consumption, g/d b 36 ± 98 1,291 ± ± ± 114 Weight, excluding wter, g/d 1,283 ± ± 18 1,316 ± 119 1,48 ± 111 Energy density, including wter, kcl/g.15 ±.3.7 ±.2. ±.3.13 ±.2 Energy density, excluding wter, kcl/g. ±.3.17 ±.3.24 ±.3.15 ±.3 Food only Energy, kcl/d 1,756 ± 126 1,36 ± 85 1,793 ± 129 1,355 ± 88 Weight, g/d 1,27 ± ± 145 1,123 ± 8 1,327 ± 149 Energy density, kcl/g 1.74 ± ± ± ±.1 Physicl ctivity, steps/d 7,73 ± 717 7,349 ± 682 6,749 ± 87 7,51 ± 767 Dt re presented s men ± s.e.m. Significnt min effect of time, P <.1. b Significnt group by time interction, P <.5. c Clculted with ll foods nd beverges, including wter. d Significnt group by time interction, P <.1. Weight loss (Kg) Nonwter group Week Wter group % CI Weight loss over time Figure 2 Weight loss mong wter nd nonwter group prticipnts over the 12-week intervention. 12-week intervention (wter: Δ.6 ±.9 mg/dl; nonwter: Δ 3.9 ±.9 mg/dl; P =.1). Averge weekly wter intke complince mong wter group prticipnts ws reported to be 9 ± 2%, nd n objective indictor of complince, urinry specific grvity, declined over time in the wter group s compred to the nonwter group (Tble 2). The increse in urine volume over time ws not different between groups. Due to n unintended greter rndom lloction of men to the wter group thn nonwter group (Tble 1), dditionl nlyses were performed to determine if weight loss outcomes differed between men nd women in two groups. Totl weight loss ws not different (ll P >.5) mong men nd women in ech diet group (wter: men 7.7 kg, women 7. kg, both ~8% of initil weight lost; nonwter: men 6.7 kg, women 5. kg, both ~6% of initil weight lost) or in the pooled smple (men 7.3 kg, women 5.7 kg, ~7% of initil weight). Dietry intke nd physicl ctivity outcomes over the 12-week intervention re presented in Tble 3. There were no bseline group differences in men dily EI or dietry ED, but severl differences were detected in dietry outcomes t bseline compred to week 12. Men dily EI declined similrly in both groups. Totl dietry ED (food + ll beverges, including wter) declined more in the wter group s compred to the nonwter group. After 12 weeks, both groups hd significntly reduced EI from beverges to ~1% of totl EI, nd wter group prticipnts demonstrted greter increses in wter nd totl fluid consumption thn the nonwter group prticipnts. Beverge ED, both including nd excluding wter, declined in both groups but no group differences in beverge ED were detected. Similrly, energy nd ED from food lone decresed in both groups, but no group differences were found. Dietry chnges ssocited with reductions in body 34 VOLUME 18 NUMBER 2 februry 1

6 weight included chnges in wter intke (r =.35, P =.3), nd bsolute nd reltive ft intke (ft grms: r =.36, P =.3; percent energy from ft: r =.44, P =.5). No other significnt ssocitions of dietry intke vribles with weight chnges were found. Physicl ctivity level did not chnge during the 12-week intervention. Of the 31 prticipnts completing the exit survey, 11 (wter group, n = 8; nonwter group, n = 3) believed tht wter ws involved some spect of the study, nd of those, eight (wter group, n = 7; nonwter group, n = 1) ccurtely identified the purpose of the study. VAS rting (mm) b VAS rting (mm) b c Ad libitum test mels In the pooled smple, men d libitum brekfst mel EI ws lower in the WP condition s compred to the NP condition t bseline (WP 498 ± 25 kcl, NP 541 ± 27 kcl, P =.9) but not t week 12 (WP 48 ± 25 kcl, NP 56 ± 25 kcl, P =.69). No significnt group by condition differences were found in brekfst mel EI, when expressed in either in bsolute (kcl) or reltive (% chnge) terms. Subjective rtings of hunger, fullness, nd thirst during the two test mel conditions t bseline nd t 12 weeks re shown in Figures 3 nd 4, respectively. Hunger AUC rtings did not VAS rting (mm) b VAS rting (mm) b c c 1 c 1 VAS rting (mm) 8 6 VAS rting (mm) Nonwter group; no prelod Nonwter group; prelod Wter group; no prelod Wter group; prelod Nonwter group; no prelod Nonwter group; prelod Wter group; no prelod Wter group; prelod Figure 3 Visul nlog scle (VAS) rtings of () hunger, (b) fullness, nd (c) thirst mong wter nd nonwter group prticipnts t bseline in the wter prelod nd no-prelod d libitum mel conditions. Following completion of the min VAS scle, the wter prelod ws provided (wter prelod condition) (); subjects completed the next VAS scle t 3 min, nd were immeditely provided with the d libitum mel (b). VAS scles were completed following the d libitum mel t 6 min (c), nd t subsequent 3-min intervls until the completion of the 15-min testing period. Significnt difference between prelod conditions, P <.5. No group differences were detected. Figure 4 Visul nlog scle (VAS) rtings of () hunger, (b) fullness, nd (c) thirst mong wter nd nonwter group prticipnts following the 12-week intervention in the wter prelod nd no-prelod d libitum mel conditions. Following completion of the min VAS scle, the wter prelod ws provided (wter prelod condition) (); subjects completed the next VAS scle t 3 min, nd were immeditely provided with the d libitum mel (b). VAS scles were completed following the d libitum mel t 6 min (c), nd t subsequent 3-min intervls until the completion of the 15-min testing period. Significnt difference between prelod conditions, P <.5. No group differences were detected. obesity VOLUME 18 NUMBER 2 februry 1 35

7 differ significntly between groups, conditions, or over time. Fullness AUC rtings were higher in the WP compred to NP condition (8,975 ± 258 vs 8,296 ± 275 mm min, respectively; P =.2), but there were no differences between groups or over time. As would be expected, thirst AUC rtings were lower in the WP compred to NP condition (4, vs. 7,297 mm min, respectively; P <.1), nd no differences were noted between groups or over time. Hunger nd thirst AUC vlues were correlted in the WP condition (r =.496, P <.1) but not the NP condition (r =.149, P =.312). Discussion To our knowledge, this is the first rndomized controlled tril investigting the influence of incresed wter consumption on weight loss. Our results indicte tht when combined with hypocloric diet, consuming 5 ml (~16 fl oz) of wter prior to ech of the three min dily mels (1.5 l/d) leds to ~2 kg greter weight loss over 12 weeks s compred to hypocloric diet lone (Figure 2), mong middle-ged nd older dults. This difference ws ttributed to 44% greter rte of weight loss mong wter group prticipnts compred to nonwter prticipnts over the 12-week period. This effect my be due in prt to n cute reduction in mel EI following wter ingestion, which we observed t the bseline lbortory test mel studies. A reduction in mel EI following wter consumption is ccompnied by incresed senstions of fullness, which my fcilitte lower mel EI following wter ingestion. However, it is not cler from our findings how long this effect is sustined, s we did not observe significnt differences between mel conditions fter the 12-week weight loss intervention. Our dt re consistent with prior reports. In secondry nlysis of tril compring severl weight loss diets, Stookey et l. (13) found tht overweight women who reported drinking 1 l/d of wter over 12-month period incresed weight loss by ~2 kg compred to those who did not increse wter consumption. However, intentionlly wter consumption ws not mnipulted, nd wter consumption dt ws self-reported. Nonetheless, our dt re in greement with these findings in tht they support beneficil role of incresing wter consumption while consuming hypocloric diet. Though the exct mechnism responsible for the greter weight loss with incresed wter consumption is presently unknown, consuming wter before mel or with mel reduces senstions of hunger, nd increses stiety (15 17). First, chnges in subjective senstions of hunger nd stiety re ssocited with n cute reduction in mel EI (16,17), but prior to our study it ws unknown if this cute reduction in mel EI could fcilitte weight loss while consuming hypocloric diet. Advncing ge is lso ssocited with delyed gstric emptying (31) tht my ply role in reducing mel EI following WP in middle-ged nd older dults; this possibility wrrnts further investigtion. We did not detect group differences in selfreported EI over the 12-week intervention, possibly due to the limittions ssocited with utilizing self-reported dietry intke mesures (32). Studies including objective mesures of dily EI, such s those conducted on n in-ptient metbolic reserch unit, re needed to more ccurtely quntify the potentil dily reduction in EI ssocited with incresed wter ingestion. Second, replcing energy-contining beverges in the diet with wter my led to reduction in overll EI, s epidemiologicl dt suggests tht totl beverge energy contributes > kcl to dily EI (33). In our smple, beverge EI declined by ~1 kcl over the 12-week intervention, but did not differ between groups nd is thus unlikely to explin our findings. As both groups were instructed to moderte their consumption of sweetened energycontining beverges nd lcohol, the lck of group difference in beverge EI nd nonwter beverge consumption is not unexpected. However, in the entire smple, greter increse in wter intke ws positively ssocited with weight loss. In ddition, overll dietry ED (food + beverges, including wter) decresed significntly more in the wter group thn the nonwter group which my be ttributed to n incresed wter intke mong wter group prticipnts; reducing dietry ED is thought to be n effective weight loss strtegy (34). Finlly, it is possible tht dily self-monitoring of wter intke contributed to greter weight loss in our wter group prticipnts, s others hve demonstrted benefits of dily selfmonitoring behviors ssocited with weight mngement (i.e., dily self-weighing) (35). Further reserch is wrrnted to determine the reltive contributions of ech of these possible physiologicl nd behviorl mechnisms relted to wter consumption promoting weight loss. There re some limittions tht should be cknowledged. First, the smple size ws smll. However, this smple size provided sufficient power to detect physiologiclly nd sttisticlly significnt effects in mny outcome vribles which were consistent with our hypothesis. Second, no stndrdized lbortory test is vilble to objectively ssess complince with the wter intervention. We utilized urinry specific grvity, 24-h urine collections, self-reported dily complince logs, nd food intke records. These procedures provided resonble indictors of complince when compring the two groups over time nd there ws consistency mong most of these mesures. Finlly, these results my not pply to the generl popultion, in tht our study only included primrily white, middle-ged nd older dults. Rolls et l. (18) did not observe difference in mel EI in young, norml-weight men who were given 8 nd 16 oz of wter 3 min prior to mel s compred to no beverge. This observtion is consistent with our findings in young dults (16). Future studies exmining premel wter intke in younger popultions could ddress methodologicl chnges such s incresing the quntity of the WP, or reducing the time between the prelod ingestion nd the d libitum mel. These findings my hve clinicl implictions. Our prior work (16,17) led us to hypothesize tht premel wter consumption could reduce dily EI by ~225 kcl, nd over 12-week period, could produce n energy deficit of ~18,9 kcl nd led to ~2.5 kg weight loss. Although we recognize this is n extrpoltion, it is consistent with our findings. Dietitins nd other weight mngement prctitioners often dvise individuls desiring weight loss to increse their wter consumption, nd this strtegy is often recommended in populr weight loss progrms (36 38). 36 VOLUME 18 NUMBER 2 februry 1

8 These findings provide n evidence-bsis for this strtegy mong middle-ged nd older dults. In ddition, incresing wter consumption is simple, inexpensive behviorl chnge which cn be recommended s component of hypocloric diet to possibly enhnce weight loss outcomes. Another potentil helth benefit of this strtegy is improved hydrtion sttus, s hbitul fluid intke mong our popultion (Tble 2) ws well below current guidelines (39). Thus, our findings suggest benefits of incresing wter consumption for weight mngement nd helth mong middle-ged nd older dults. We conclude tht for overweight or obese middle-ged nd older dults, consuming ~2 cups of wter prior to ech of the three min dily mels my increse weight loss when combined with hypocloric diet, s compred to hypocloric diet lone. This strtegy my id in incresing fullness, thereby promoting reduction in mel EI. Future studies, with lrger smple sizes, re needed to confirm our findings s well s to determine how long the cute reduction in mel EI following wter ingestion is sustined; if this incresed weight loss with wter consumption is mintined over time; nd if incresed wter consumption fcilittes long-term weight loss mintennce. Acknowledgments Funding for this investigtion ws provided by reserch grnt from the Institute for Public Helth nd Wter Reserch. Disclosure The senior uthor (B.M.D.) hs received reserch funding for this investigtion from the Institute for Public Helth nd Wter Reserch 9 The Obesity Society References 1. Wng Y, Beydoun MA, Ling L, Cbllero B, Kumnyik SK. Will ll Americns become overweight or obese? estimting the progression nd cost of the US obesity epidemic. Obesity (Silver Spring) 8;16: Ogden CL, Crroll MD, Curtin LR et l. Prevlence of overweight nd obesity in the United Sttes, JAMA 6;295: Vn Wlleghen EL, Orr JS, Gentile CL, Dvy KP, Dvy BM. 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Wter consumption reduces energy intke t brekfst mel in obese older dults. J Am Diet Assoc 8;18: Rolls BJ, Kim S, Fedoroff IC. Effects of drinks sweetened with sucrose or sprtme on hunger, thirst nd food intke in men. Physiol Behv 199;48: Cnty DJ, Chn MM. Effects of consumption of cloric vs noncloric sweet drinks on indices of hunger nd food consumption in norml dults. Am J Clin Nutr 1991;53: Holt SH, Sndon N, Brnd-Miller JC. The effects of sugr-free vs sugr-rich beverges on feelings of fullness nd subsequent food intke. Int J Food Sci Nutr ;51: Rodin J. Comprtive effects of fructose, sprtme, glucose, nd wter prelods on clorie nd mcronutrient intke. Am J Clin Nutr 199;51: Ledikwe JH, Blnck HM, Khn LK et l. Dietry energy density determined by eight clcultion methods in ntionlly representtive United Sttes popultion. J Nutr 5;135: Rolls BJ, Kim S, McNelis AL et l. Time course of effects of prelods high in ft or crbohydrte on food intke nd hunger rtings in humns. 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Hrper Collins: New York, Pnel on Dietry Reference Intkes for Electrolytes nd Wter. In: Institute of Medicine (ed). The Dietry Reference Intkes: The Essentil Guide to Nutrient Requirements. Dietry Reference Intkes for Wter, Potssium, Sodium Chloride, nd Sulfte. Ntionl Acdemy Press: Wshington, DC, 4, pp obesity VOLUME 18 NUMBER 2 februry 1 37