When young women who are overweight drink an extra six glasses of water a day before meals for two months, they tend to lose a little weight, their BMI goes down a bit, and their body fat measurements slightly improve.
Scientific Claim
In overweight young women aged 18–23, consuming an additional 1.5 liters of water per day (500 ml three times daily before meals) for eight weeks is associated with a mean reduction of 1.44 kg in body weight, a decrease of 0.58 kg/m² in BMI, and a reduction of 3.05 mm in total skinfold thickness at three body sites, suggesting a modest link between increased water intake and improved body composition metrics.
Original Statement
“The mean values of the pre-study and post-study body weight, body mass index and body composition scores were 65.86 kg and 64.42 kg, 26.7002 and 26.1224 and 79.626 mm and 76.578 mm respectively. All the three results were highly significant statistically.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The study design lacks a control group, randomization, and confounder adjustment, so it cannot establish causation. The authors incorrectly use 'establishes the role' — a causal phrase — when only an association was observed.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Systematic Review & Meta-AnalysisLevel 1aWhether increased water intake consistently leads to small reductions in body weight and fat mass across diverse populations of overweight adults, controlling for diet and activity.
Whether increased water intake consistently leads to small reductions in body weight and fat mass across diverse populations of overweight adults, controlling for diet and activity.
What This Would Prove
Whether increased water intake consistently leads to small reductions in body weight and fat mass across diverse populations of overweight adults, controlling for diet and activity.
Ideal Study Design
A meta-analysis of 15+ high-quality RCTs including adults aged 18–40 with BMI 25–29.9, comparing 1.5 L/day extra water (consumed 30 min before meals) vs. no change in water intake, with primary outcomes of body weight, BMI, and DXA-measured fat mass after 8–12 weeks, adjusting for energy intake and physical activity.
Limitation: Cannot determine biological mechanisms or long-term sustainability of effects.
Randomized Controlled TrialLevel 1bWhether the observed changes in weight and body fat are directly caused by increased water intake, not by unmeasured behavioral changes.
Whether the observed changes in weight and body fat are directly caused by increased water intake, not by unmeasured behavioral changes.
What This Would Prove
Whether the observed changes in weight and body fat are directly caused by increased water intake, not by unmeasured behavioral changes.
Ideal Study Design
A double-blind, placebo-controlled RCT of 100 overweight women aged 18–23, randomized to drink 1.5 L/day water before meals or 1.5 L/day of a taste-matched placebo beverage, with dietary and activity logs monitored, and body composition measured via DXA at baseline and 8 weeks.
Limitation: Blinding is difficult with water vs. placebo; compliance may still vary.
Prospective Cohort StudyLevel 2bWhether habitual water intake predicts long-term changes in body weight and fat mass in real-world settings.
Whether habitual water intake predicts long-term changes in body weight and fat mass in real-world settings.
What This Would Prove
Whether habitual water intake predicts long-term changes in body weight and fat mass in real-world settings.
Ideal Study Design
A 1-year prospective cohort of 500 overweight adults aged 18–30, tracking daily water intake via digital logs and body composition via bioimpedance every 3 months, adjusting for diet, sleep, and physical activity.
Limitation: Cannot rule out residual confounding from unmeasured lifestyle factors.
Case-Control StudyLevel 3bWhether individuals who successfully lost weight differ in water intake patterns compared to those who did not, among overweight adults.
Whether individuals who successfully lost weight differ in water intake patterns compared to those who did not, among overweight adults.
What This Would Prove
Whether individuals who successfully lost weight differ in water intake patterns compared to those who did not, among overweight adults.
Ideal Study Design
A case-control study comparing 100 overweight adults who lost ≥5% body weight over 6 months with 100 matched controls who did not, retrospectively analyzing daily water intake via food diaries and biomarkers.
Limitation: Relies on recall bias and cannot establish temporal sequence.
Cross-Sectional StudyLevel 4Whether higher water intake correlates with lower BMI or body fat in a population at a single point in time.
Whether higher water intake correlates with lower BMI or body fat in a population at a single point in time.
What This Would Prove
Whether higher water intake correlates with lower BMI or body fat in a population at a single point in time.
Ideal Study Design
A cross-sectional survey of 2,000 overweight adults aged 18–30 measuring self-reported daily water intake and objectively measured BMI and skinfold thickness, adjusting for socioeconomic and dietary factors.
Limitation: Cannot determine direction of causality or changes over time.
Evidence from Studies
Supporting (1)
This study gave overweight young women extra water before meals for eight weeks, and they lost a little weight, their BMI went down, and their body fat decreased—exactly what the claim says.