A secondary analysis of two randomized crossover studies published in the journal Appetite suggests that drinking water during meals and alternating sips with bites of food are associated with increased food intake. The findings contradict common weight-loss advice that suggests water consumption helps reduce total energy intake by promoting satiety.
Revisiting the Water-for-Weight-Loss Strategy
For many, the habit of keeping a glass of water beside a plate is a cornerstone of dietary management. The conventional wisdom is straightforward: water takes up space in the stomach, creating a physical sense of fullness that naturally limits how much food a person consumes. Yet, new research indicates that this strategy may be counterproductive.
In a secondary analysis of 172 meals involving 86 participants, researchers observed that higher water intake during lunch was linked to greater consumption of food. Specifically, for every additional 100 grams of water consumed, participants ate approximately 39 more grams of food and took in 49 extra calories. While water itself contains no calories, the habit appears to influence the overall volume of food ingested, challenging the widespread belief that hydration effectively curbs appetite during meals.
The Mechanics of the Lab-Based Study
The research, conducted by Paige M. Cunningham of Cornell and John E. Hayes of Penn State, utilized data from two previous randomized crossover studies. Participants were served oversized 650-gram portions of either beef chili or chicken tikka masala, accompanied by 450 grams of water. By providing more food than any individual could finish, researchers ensured they could track voluntary intake without hitting a ceiling effect.
The study group was diverse in its habits but consistent in its demographic profile. Participants averaged 37 years of age, with 71 percent being women and 71 percent identifying as White. Most held university degrees and reported household incomes of less than $100,000 USD. Approximately 44 percent were classified as having overweight or obesity based on BMI calculations.
Switching Between Bites and Sips
Beyond the total volume of water consumed, the researchers analyzed the physical act of eating. Video recordings allowed the team to count every time a participant put down a utensil to pick up a glass, a behavior they defined as a “switch.” Each alternation between a bite of food and a sip of water was linked to about 4.4 more grams of food and 5.8 additional calories.
As noted in the study published in Appetite, this behavior challenges the widespread dietary advice to drink water with meals to reduce food intake.
The researchers favor the theory of sensory-specific satiety—the idea that the appeal of a particular food fades as one continues to eat it. By interspersing sips of water, diners may be refreshing their palate and extending the time they find the food palatable, thereby consuming more.
Surprising Findings on Drinking Rate and Fullness
Not every observation aligned with the researchers’ expectations. While slower, deliberate drinking was associated with higher intake, faster drinking was paradoxically linked to less food consumption. This specific result was described by the researchers as surprising,
as there is currently no clear explanation for why the speed of water intake would have an inverse effect on total food volume.
Furthermore, the psychological experience of the participants did not match their physical intake. Even though those who drank more water ate more food, they also reported feeling fuller after the meal than those who drank less. This discrepancy suggests that the physiological sensation of satiety may not always accurately reflect the quantity of energy consumed.
Causality and Future Considerations
Despite the strong correlations observed in the data, the researchers emphasized that the study design prevents a definitive claim that water consumption causes increased food intake. Because participants were not assigned specific amounts of water to drink, but rather chose their own consumption levels, it remains possible that other factors influenced both drinking and eating behaviors simultaneously.
“The associations observed here should be taken cautiously in terms of causality.”
Cunningham and Hayes, Authors of the study published in Appetite
For those looking to manage their weight, these findings suggest that the simple act of drinking water during a meal may not be the universal solution many assume it to be. As the research continues, the focus remains on how small, often unconscious behaviors—such as the number of sips taken or the frequency of switching between food and drink—shape our overall energy balance at the table.
Sources: News Medical, StudyFinds.
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