Immediate pre-meal water ingestion decreases voluntary food intake in lean young males

Purpose: Consuming 375-500 ml of water 30 min before a meal has been shown to reduce energy intake in older, but not younger adults. This study investigated the effects of ingesting a water preload immediately pre-meal (<1 min before eating) on within-meal ad-libitum energy intake in non-obese young males. Methods: Fourteen healthy males (mean (SD) age 27 (3) y, Height 1.83 (0.05) m, body weight 80.47 (9.89) kg, body fat 17.5 (4.0) %, body mass index 24.0 (2.5) kg/m2) completed a familiarisation trial and two experimental trials in randomised counterbalanced order. Subjects arrived at the laboratory overnight fasted and consumed an ad-libitum porridge breakfast. Immediately prior to the meal, subjects consumed either a 568 ml (1 pint) water preload (preload trial) or no preload (control trial). Visual analogue scale questionnaires to assess hunger, fullness and satisfaction were completed before and after the meal in both trials, as well as after the water preload. Results: Ad-libitum energy intake was greater (P<0.001) during control (2551 (562) kJ) than preload (1967 (454) kJ). Ad-libitum water intake was also greater (P<0.001) during control (318 (226-975) ml) than preload (116 (0-581) ml). The water preload increased fullness and satisfaction and decreased hunger compared to pre-trial (P<0.001) and the control trial (P<0.001). Conclusion: This study demonstrates that consumption of a 568 ml water preload immediately before a meal reduces energy intake in non-obese young males. This might therefore be an effective strategy to suppress energy intake in this population and possibly assist with weight management

Effects of aging on the opioid modulation of feeding in humans

The definitive version is available at www.blackwell-synergy.comOBJECTIVES:To determine whether aging is associated with a reduction in the opioid modulation of feeding, which may be important in the pathogenesis of the "anorexia of aging." DESIGN:Three studies on separate days, in randomized order and double-blind fashion. SETTING:Clinical Human Research Laboratory, Department of Medicine, RAH, Adelaide, Australia. PARTICIPANTS:Twelve older (5 male/7 female) (age 65-84) and 12 young (5 male/7 female) (age 20-26) healthy subjects. INTERVENTION:Subjects received in double-blinded random order, intravenous bolus (10 minutes) and then continuous (140 minutes) infusions of saline (control), naloxone low dose (LD) (bolus 27 microg/kg; continuous 50 microg/kg/hr), or naloxone high dose (HD) (bolus 54.5 microg/kg; continuous 100 microg/kg/hr). MEASUREMENTS:After 120 minutes, subjects were offered a buffet meal, and their energy intake was quantified. Hunger, fullness, nausea, and drowsiness were assessed using visual analogue scales. RESULTS:The naloxone LD and HD infusions had no significant effect on ratings of hunger, fullness, or nausea, but increased drowsiness (P < .01) compared with the control infusion in both age groups. Older subjects ate less (P < .001) at the buffet meal than young subjects during all three infusions. Naloxone infusions reduced energy intake compared with control (P < .001), LD by 13.2 +/- 5.0% and HD by 10.7 +/- 5.0%, with no difference between the doses (P = .71). Overall, naloxone suppressed energy intake in both young and older subjects (P < .01). This suppression was slightly, but not significantly, greater in young than in older subjects (mean of LD and HD 16.4 +/- 4.9% vs 7.5 +/- 4.9%, P = .42), because of a trend to reduced suppression in older women. CONCLUSIONS:We conclude that healthy older adults retain their sensitivity to the suppressive effects of naloxone on food intake. Possible gender differences in this sensitivity warrant further investigation. A decline in opioid activity is unlikely to contribute substantially to the physiological anorexia of aging observed in older people.Caroline G. MacIntosh, Jessica Sheehan, Nusha Davani, John E. Morley, Michael Horowitz, Ian M. Chapma