Water Intake and Weight Control in Older Adults

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Project Summary/Abstract The lack of practical and effective strategies to manage hunger and adhere to a weight management intervention represents a critical barrier to the weight management field. In proof-of-concept efficacy studies, we have demonstrated that premeal water consumption (500 ml) acutely reduced perceived hunger and meal energy intake among middle-aged and older adults, and that premeal water consumption (500 ml, 3 times per day) increased the amount of weight lost (i.e., 2 kg greater loss) after 12 weeks among middle-aged and older adults with overweight or obesity. However, water consumption may be important for weight management regardless of when it is consumed. To address this possibility, we propose a rigorously-designed randomized controlled intervention trial in adults aged 50+ years with overweight or obesity comparing three groups with different diet prescriptions: 1) pre-meal water consumption (500 ml, before each main meal) with a hypocaloric diet; 2) 1500 ml water consumed throughout the day with a hypocaloric diet; 3) hypocaloric diet with no instructions regarding water consumption. Smart water bottles will objectively assess water intake timing and volume. Urine osmolality, urine volume, and serum osmolality will be used as objective indicators of compliance with the water intake prescription. We will investigate changes in perceived hunger and fullness and appetite-regulating hormones as potential mechanisms by which premeal water could improve appetite regulation. We will also investigate the impact of water consumption and hydration on executive function capabilities, which may influence intervention adherence. We hypothesize that weight loss at 12 weeks, and weight loss maintenance at 12 months, will be greater in the premeal water group compared to the daily water volume and control groups. Furthermore, when combined with a hypocaloric diet, premeal water will reduce hunger and increase fullness; these changes will mediate adherence to the hypocaloric diet and weight loss outcomes. Although increasing water intake could be an effective weight management strategy, no evidence-based recommendations exist for the timing of water intake needed for this benefit. Our findings could identify a low-cost, actionable dietary strategy that could be incorporated into clinical practice guidelines for obesity treatment, and improve adherence to a hypocaloric diet prescription through reduced hunger, increased fullness, and improved attention and inhibitory control. This proposal is aligned with the 2020-2030 NIH Strategic Plan for Nutrition Research (Objective 3.5) and the Dietary Guidelines for Americans 2020-2025 due to its focus on older adults, an understudied population at increased risk for obesity and inadequate hydration. If effective, this hydration/weight control intervention approach could be applied to clinical populations such as adults with obesity who are prescribed increased water intake to prevent or treat kidney stone disease or urinary tract infections, which are common in older adults.