A new review of prior research, featured in the journal Appetite, challenges the widespread belief that drinking water promotes satiety during meals. Meanwhile, a related study in Food Quality and Preference revealed that spicy salsa—often avoided by those on a diet—actually reduces the total amount of food consumed.
A common dietary recommendation is to drink more water in order to manage body weight and control energy intake.
This advice is highly prevalent: a 2019 study found that among 42% of 48,026 participants who reported trying to lose weight at the time of the survey, increasing water intake was the third most popular strategy, following only reducing food consumption and boosting physical activity.
The logic behind this suggestion seems straightforward—it is thought that drinking water before or during meals enhances stomach distension, which in turn promotes greater feelings of fullness and ultimately reduces the amount of food eaten.
“There is a widespread notion that drinking water fills us up,” said Professor Paige Cunningham from Cornell University. “However, water leaves the stomach quickly, so it is unlikely to keep us full for long. On the contrary, water may actually increase the volume of food consumed by providing lubrication that accelerates the eating process and by preventing dry mouth, which could prolong the pleasure of eating.”
The authors combined data from two crossover experiments in which adults ate a 650-gram meal of beef chili or chicken tikka masala, accompanied by 450 grams of water, on two separate occasions in a laboratory setting, all while being recorded on video.
In both experiments, the spiciness of the meal was varied by adjusting the ratio of spicy to sweet paprika.
The video recordings were analyzed to track the number of sips, sip size, drinking speed, and the frequency of switching between eating and drinking water.
For every additional 100 grams of water consumed, participants in the experiments ate roughly 39 grams more food—equivalent to about 49 additional calories.
Individuals who frequently alternated between eating and drinking consumed even more: each additional switch was linked to an increase in food intake of approximately 4.4 grams.
In a parallel study, 49 adults were served corn chips with either mild or spicy salsa once a week for two weeks, with only the cayenne pepper content in the salsa varying between conditions.
The spicier version led to a 28% reduction in total snack consumption—not just of the salsa itself, but also of the chips, even though the chips themselves remained unchanged.
Participants ate the spicy snack about 30% more slowly than the mild one, which researchers believe accounts for the decrease in intake: the heat slowed down the eating process, and slower eating resulted in less overall consumption.
Water intake during the snack did not differ based on the level of spiciness, ruling out this factor as an explanation for the reduced consumption.
“Both studies highlight how meal characteristics and food properties can significantly influence the amount we eat, even without our awareness,” explained Professor Cunningham. “We discovered that simply increasing water intake was associated with a rise in total food consumption, whereas adding a modest amount of spice to a snack slowed down eating and reduced the amount participants ate.”
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