Real scientists are open to the possibility they could be wrong
By Laura Reiley, Cornell University
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| Credit: Laila Milevski/Cornell University |
The common rationale for drinking water at meals is that it physically stretches the stomach, triggering fullness so you don't eat too much. But a new Cornell study found no support for that idea in practice. The paper is published in the journal Appetite.
Instead, for every additional 100 grams of water participants drank, they ate about 39 more grams of food—roughly 49 more calories. People who frequently switched back and forth between bites of food and sips of water ate even more: Each additional switch was tied to about 4.4 more grams of food consumed.
Researchers suspect this "switching" effect works
by delaying something called sensory-specific satiety—the way a food's appeal
naturally fades the longer you eat it. Alternating with water may reintroduce
contrast that keeps the meal appealing longer, delaying the point at which
people stop eating.
"There's been this widespread advice that if we drink water, it fills us up," said Paige Cunningham, assistant professor in the Division of Nutritional Sciences in the College of Human Ecology. "But water empties quickly from the stomach, so it likely doesn't fill us up for long. Instead, water may increase how much we eat, providing lubrication that can speed up eating and preventing dry mouth, which can prolong enjoyment of the food."
A second test of meal habits
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| Credit: Laila Milevski/Cornell University |
In a second related study, the researchers measured the
effect of spicy salsa on eating volume—and again found a surprising result.
"Both studies show how mealtime behaviors and food
properties can significantly influence how much we eat, without us even
realizing. We found that just
drinking more water was associated with greater
consumption, while adding a bit more spice to a snack slowed eating and
decreased how much participants ate," Cunningham said.
The drinking water study pooled data from two earlier lab
experiments involving 86 adults who ate as much as they wanted of a lunch
(either beef chili or chicken tikka masala) served with water, while
researchers recorded every bite and sip on video.
One result cut against the researchers' own expectations: Participants who drank water faster during a meal ended up eating less, not more. The paper offers this as a genuine open question rather than a settled explanation, noting it may reflect how long water sits in the mouth or may simply track how long a meal lasts overall.
Spice slowed snacking down
"This was a secondary analysis looking at
associations," Cunningham said. "We are following up on this right
now so we can make those causal inferences."
In a separate experiment, whose results were published in Food Quality and
Preference, 49 adults were served tortilla chips alongside a mild or
spicy salsa once a week for two weeks; only the salsa's cayenne content changed
between conditions. The spicier version cut the total snack intake by 28%—not
just of the salsa itself, but of the chips too, even though the chips
themselves didn't change.
Participants ate the spicy
snack about 30% more slowly than the mild one, which the researchers
suspect drove the decrease: Heat slowed people down, and slower eating meant
less eaten overall. Water intake during the snack was unaffected by spice
level, which the researchers note rules it out as an explanation for the
reduced intake.
"We were interested in whether making the salsa spicy
would result in people eating the same amount of chips," Cunningham said.
"And they didn't. The takeaway is that adding spice to one part of the
snack can significantly influence how much people eat overall."
Limits on broader takeaways
Read together, the two papers make a case that runs against
two different strands of popular nutrition advice at once: that water at meals
is a simple ally in eating less, and that spicy food is something to approach
with caution if you're watching what you eat. This research showed the opposite
might be true: Water tracked with eating more, and spice tracked with eating
less.
"These strategies might help consumers achieve their
goals to reduce energy intake," Cunningham said.
Both papers are explicit about their limits: The meals and
snacks tested were a narrow set—chili, tikka masala and one chip-and-salsa
combination—all eaten in a controlled lab setting, and the researchers caution
against assuming the same patterns would hold for very different foods or in
everyday, uncontrolled eating.
"We are looking to future experiments that explore what
other factors or properties of foods we can leverage to influence
behaviors," Cunningham said.
Publication details
Paige M. Cunningham et al, Water intake, switching between
bites and sips, and drinking behavior are associated with food intake across
meals varying in spiciness: A secondary analysis of two randomized crossover
studies, Appetite (2026). DOI:
10.1016/j.appet.2026.108698
Paige M. Cunningham et al, Increasing the spiciness of a
snack slows eating and reduces food and energy intake, Food Quality and
Preference (2026). DOI:
10.1016/j.foodqual.2026.105951
Journal information: Food
Quality and Preference , Appetite
