Fluid Intake and Chronic Disease: Kidney Stones, Weight and Other Outcomes
Increased fluid intake halved recurrent kidney-stone risk in a review of randomised trials (Fink 2013); replacing sugar-sweetened beverages with water may offer a modest weight-loss benefit while general water intake did not significantly change adiposity (Chen 2024); for overactive bladder, reducing fluid intake reduced symptoms (Callan 2015); and a systematic review reports no benefit from eight glasses a day in people without kidney stones (Wood 2018).
Not for clinical populations without professional guidance
- Signs of disordered eating (food/weight preoccupation, restriction, bingeing, purging, compulsive exercise): see a qualified eating-disorder professional
- Diagnosed medical condition (diabetes, chronic kidney disease, heart failure, GI disease): see a registered dietitian or physician
- Pregnancy or breastfeeding: see a prenatal provider or registered dietitian
- Unintentional weight loss, difficulty swallowing, or persistent GI symptoms: seek medical evaluation
What the evidence says
The sources on this entry are systematic reviews and meta-analyses of fluid intake and clinical outcomes, cohort studies of beverages and weight, and narrative reviews of hydration and disease. For kidney stones, Fink 2013 (systematic review of 28 randomised trials) reports that increased fluid intake halved recurrent stone risk (RR 0.45) and that reduced soft-drink intake carried a recurrence risk ratio of 0.83; Bao 2012 (Cochrane review) reports one study of 199 patients with lower recurrence in the increased-water group and concludes that increased water intake may reduce recurrence based on limited evidence, with no evidence for primary prevention; Asher 2026 (systematic review of 31 studies) reports that increased water intake and dietary modification may reduce recurrence, with evidence largely of low strength; Lin 2020 (meta-analysis of 50 articles, 1,322,133 participants) reports fluid intake (0.55) and the DASH diet (0.69) as protective factors for incident stones; Rauzi 2026 (systematic review of 80 studies) reports low fluid intake as a risk factor in rural settings (OR 2.64); Kandefer 2026 (narrative review) reports that the evidence supports high fluid intake for nephrolithiasis; and Wood 2018 (systematic review) reports level 1 evidence for increased fluid in nephrolithiasis and no evidence for increased fluid in cardiovascular disease, constipation, venous thromboembolism, headaches, cognition or bladder cancer. For body weight, Daniels 2010 (systematic review) reports total energy intake 7.8% higher when sugar-sweetened beverages were consumed instead of water and concludes that reduced energy intake is expected when water replaces caloric beverages at a meal but may not translate into long-term weight change; Pan 2013 (cohort) reports each extra cup of water a day inversely associated with 4-year weight gain (−0.13 kg) while sugar-sweetened beverages (+0.36 kg) and fruit juice (+0.22 kg) were associated with gain; Chen 2024 (meta-analysis of 8 randomised trials) reports that water intake did not significantly affect adiposity and that replacing sugar-sweetened beverages with water may offer a modest weight-loss benefit; Hakam 2024 (systematic review of 18 randomised trials) reports increased water intake associated with greater weight loss and fewer stone events, with single studies suggesting non-significant benefits for migraine, urinary infection, diabetes control and hypotension, and concludes that the evidence is limited. For glycaemic parameters, Naumann 2017 (narrative review) reports low and heterogeneous evidence. El-Sharkawy 2015, Liska 2019 and Maughan 2012 (narrative reviews) report fluid imbalance and low habitual intake associated with a range of disorders and conclude that the evidence is largely associative with limited randomised trials. For overactive bladder, Callan 2015 (systematic review) reports that reducing fluid intake reduced urgency, frequency and urge incontinence and that increasing fluid by 25–50% could worsen symptoms, and Wood 2018 reports that excess fluid can exacerbate them.
- Do not claim any food, diet, or supplement cures, treats, or prevents any disease
- Do not diagnose nutrient deficiencies or medical conditions
- Do not promise specific weight-loss amounts or timelines
- Do not deliver individualized medical nutrition therapy or replace clinical care
- Agreement
- Direction recorded for 0 of 16 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- No source states a certainty rating.
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (16)
- What it measured
- Benefits and harms of interventions to prevent recurrent kidney stones (stone outcomes)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review (for ACP clinical guideline)
- Studies and participants, as stated
- 28 RCTs
- What it measured
- Prevention of urinary stones and recurrence
- How it was read
- screened only, not extracted
- What the review says it includes
- Cochrane systematic review of randomized/quasi-randomized controlled trials
- Studies and participants, as stated
- 1 study, 199 patients (secondary prevention); 0 studies for primary prevention
- What it measured
- Associations between modifiable lifestyle/dietary factors and incident nephrolithiasis
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review and meta-analysis (observational studies and RCTs)
- Studies and participants, as stated
- 50 articles; 1,322,133 participants; 21,030 cases
- What it measured
- Risk factors for urinary tract stones in rural settings
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review
- Studies and participants, as stated
- 80 studies
- What it measured
- Prevention of recurrent nephrolithiasis (benefits and harms of diet, pharmacologic therapy, surveillance imaging)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review of randomized controlled trials and nonrandomized studies of interventions
- Studies and participants, as stated
- 31 studies (26 RCTs, 5 NRSIs)
- What it measured
- Role of diet, obesity, dietary patterns in nephrolithiasis and urologic cancers; practical dietary counselling
- How it was read
- screened only, not extracted
- What it measured
- Change in total energy intake (ΔTEI).
- How it measured it
- ΔTEI formula (objective).
- How it was read
- read in full text
- What it measured
- Long-term weight change associated with changes in water/beverage intake
- How it was read
- screened only, not extracted
- What it measured
- Body weight, BMI, WC.
- How it measured it
- Objective measurements (mean differences and standard deviations).
- How it was read
- read in full text
- What the review says it includes
- Meta-analysis of 8 RCTs
- Studies and participants, as stated
- N=[not reported] participants across 8 studies
- Heterogeneity, as stated
- High heterogeneity in some meta-analyses
- What it measured
- Benefits of changing daily water intake (weight, nephrolithiasis, and other outcomes)
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review of randomized clinical trials
- Studies and participants, as stated
- 18 RCTs
- What it measured
- Effect of drinking water/mineral water on glycemic parameters
- How it was read
- screened only, not extracted
- What it measured
- Impact of hydration status on health/disease
- How it was read
- based on the abstract, not the full text
- What it measured
- Role of hydration in health outcomes (skin, neurological, GI/renal, body weight/composition)
- How it was read
- screened only, not extracted
- What it measured
- Association of fluid deficits with morbidity and mortality
- How it was read
- screened only, not extracted
- What it measured
- Health effects of increased water intake and identification of subpopulations needing increased hydration
- How it was read
- based on the abstract, not the full text
- What it measured
- Effect of increasing/decreasing daily water/fluid intake on OAB symptoms
- How it was read
- screened only, not extracted
- What the review says it includes
- Systematic review (Evidence Based Report Card)
- Studies and participants, as stated
- 10 articles met inclusion (from 260 identified, 48 full-text)
Every source below is shown with its study design and links to the original study. This is the audit trail.
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.