Elderly people trying to eat less may benefit from drinking a large glass of water before meals, suggest two studies from the USA.
Scientists from Virginia Polytechnic Institute and State University recruited 50 people to test whether drinking a large glass of water 30 minutes before lunch can reduce caloric intake at lunch. Aiming to compare the effects also regarding age, their sample consisted of 29 young adults (21 to 35 years old, 14 men and 15 women) and 21 older ones (60 to 80 years old, 10 men and 11 women), all of whom were healthy and non-obese. The participants reported to the laboratory for two lunches (on separate days and in random order), one with a water preload 30 minutes before the meal and another without water preload. Women received 375 ml and men 500 ml water. The participants freely selected their meals from a buffet and rated their fullness, hunger and thirst every 30 minutes, starting from 30 minutes before lunch - prior to the pre-load - till 120 minutes after lunch. Additionally, energy intake at the two lunch meals was recorded. The water preload reduced energy intake in older adults by ~9% (58 kcal), but had no effect in younger adults. Similarly, the older adults reported significantly higher satiety and fullness and lower hunger ratings than the young adults. Slower stomach emptying and altered sensations of fullness and satiety in the elderly may have accounted for the differences between the age groups.
Based on these findings, a research team from the same university decided to test the impact of a water preload specifically on overweight and obese older adults (55 to 75 years old, mean body mass index ,BMI, around 34 kg/m2). The procedure in this study was almost the same as in the previous one: 7 men and 27 women consumed two breakfast meals, one with and one without water preload (500 ml). This time only the amount of food eaten and the energy intake were measured. In line with the previous study, meal energy intake decreased significantly by approximately 13% (74 kcal) in the water preload group compared to the breakfast-only group.
In conclusion, these studies suggest that water consumption before a meal may help reduce energy intake in the elderly. Whether this would prevent weight gain or even lead to weight loss in the long term remains to be shown in larger studies over a prolonged period of time.
For more information, see:
Van Walleghen et al. (2007) Pre-meal water consumption reduces meal energy intake in older but not younger subjects. Obesity. 2007;15:93–99.
Davy et al. (2008) Water Consumption Reduces Energy Intake at a Breakfast Meal in Obese Older Adults. J Am Diet Assoc. 2008;108:1236-1239.
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