Could drinking water at mealtime make people eat more, and can spicy foods lead to weight loss? The answer was “yes” to both in two separate studies. But some experts urged caution.

“The advice to drink more water to eat less is really common, but research directly investigating the claim that water consumption during meals reduces food intake has been limited,” lead author Paige Cunningham, PhD, assistant professor in the Division of Nutritional Sciences in the College of Human Ecology at Cornell University in Ithaca, New York, told Medscape Medical News. “The findings actually matched our hypothesis going in, that water intake would be positively associated with food intake.”

As for spicy foods, she said, “Some epidemiological research has associated greater consumption of spicy food with greater body weight. However, this is likely due to the fact that many spicy foods are also energy dense and high in fat. Controlled studies that isolate the effects of spiciness align more with what we found, that consuming spicy food can reduce appetite and therefore could aid in weight management.”

The water study was published online in Appetite, and the spicy foods study was published online in Food Quality and Preference.

More Water, More Eating

For the water study, the researchers conducted a secondary analysis of two crossover experiments in which 52 adults ate an ad libitum lunch of 650 g of beef chili and 34 adults ate 650 g of chicken tikka masala, both with 450 g of water twice in the laboratory while being video-recorded. Participants’ mean age was 37 years, mean BMI was 25.6, and 44% reported having overweight or obesity according to BMI.

For both experiments, the spiciness of the lunch was varied by adding different ratios of hot to sweet paprika. Videos were coded to measure sip number, sip size (g/sip), drinking rate (g/min), and the number of switches between bites of food and sips of water.

Across all meals, greater water intake and switching between bites of food and sips of water were associated with greater food intake. Overall, individuals ate more when they drank more water and switched between bites and sips more often.

Specifically, for every additional 100 g of water participants drank, they ate about 39 g more food, or roughly 49 kcal more. Participants who frequently switched back and forth ate even more because each additional switch was tied to about 4.4 g more food consumed.

“This finding challenges the widespread dietary advice to drink water with meals to reduce food intake,” the authors wrote.

For the spicy foods study, researchers tested how increasing oral burn affected snacking. In a randomized crossover study, 49 adults ate tortilla chips (100 g; 540 kcal), salsa (200 g; 80 kcal), and water (450 g) in the laboratory once a week for 2 weeks. Participants’ mean age was 35 years; 65% were women; the mean BMI was 25.2, with 45% reporting having overweight or obesity.

Spiciness was manipulated by adding cayenne pepper to a commercially available salsa (mild salsa: 0.75% cayenne vs spicy salsa: 3% cayenne).

Food and water intake were assessed before and after eating. Eating rate (g/min) was determined from video recordings.

The researchers found that increasing salsa spiciness reduced total snack intake by 28%, with a 16% reduction in chip intake and a 34% reduction in salsa intake, meaning that salsa spiciness directly influenced salsa intake but also indirectly influenced chip intake.

Of note, the spice level did not influence water intake, indicating water intake did not explain differences in food intake.

In addition, the spicy snack was eaten 30% more slowly than the mild snack, suggesting that increasing spiciness reduced intake via slower eating. “These results extend previous findings in meals by indicating that moderately increasing oral burn by adding chili peppers to snacks may help reduce risk of energy overconsumption,” the authors concluded.

Study limitations included limiting the foods to a narrow set of meals and snacks eaten in a controlled laboratory setting so the findings might not hold for different foods or everyday uncontrolled eating.

Nevertheless, Cunningham said, “For patients looking to manage weight and consume less at meals, our findings indicate that the current recommendation to drink more water with meals may not be effective at reducing energy intake. I don’t think we have enough evidence right now to support clinical recommendations for weight loss, but our findings indicate that increasing the spiciness of meals and snacks might help individuals eat less.”

“Both studies show how mealtime behaviors and food properties can significantly influence how much we eat, without us even realizing,” she added.

‘Narrow, Short-Term Findings’

“These are interesting findings, but they do not prove that water causes people to eat more or that spicy food produces weight loss,” American Gastroenterological Association Spokesperson Nihar Shah, MD, Sarasota Memorial Hospital, Sarasota, Florida, told Medscape Medical News.

“These findings are not strong enough to change my general advice,” he said. “I would not tell patients to avoid water with meals because adequate hydration remains important. Patients who enjoy and tolerate spicy food may use it as one possible way to slow their eating, but it should not be considered a proven weight-loss treatment.”

“Patients with reflux or other gastrointestinal symptoms aggravated by spicy foods should individualize that choice,” he added.

Also commenting for Medscape Medical News, Mariam Naveed, MD, AdventHealth Medical Group, Altamonte Springs, Florida, said, “The data support the studies’ narrow, short-term findings but not necessarily the broader weight-loss framing.”

“The salsa result is plausible, and the study design supports a stronger inference because participants were randomly served mild and spicy versions of the same snack,” said Naveed, who is also a spokesperson for the American Gastroenterological Association. The spicier salsa slowing eating and reducing snack consumption “is consistent with a broader literature linking slower eating to lower intake.”

The water finding should be interpreted “more cautiously,” she said. While the study showed a statistically significant association between drinking more water and eating more, “it does not show that water caused them to eat more or that drinking water is unhelpful for weight management.”

“Most importantly, neither study measured weight loss,” she noted. “They measured intake during brief, controlled laboratory eating occasions. We do not know whether participants compensated by eating more or less later in the day, much less whether either behavior affected body weight over time.”

“I would not advise patients to drink less water with meals based on an observational secondary analysis, particularly because premeal water was not tested,” she said. Like Shah, she would not prescribe spicy food as a weight-loss strategy and suggested individualizing advice for patients whose reflux or irritable bowel syndrome symptoms are aggravated by spicy foods.

“If patients already enjoy and tolerate spice, adding it may be one way to slow eating, but the more clinically useful signal here is eating rate — not cayenne itself,” she added.

Shah and Naveed declared no relevant conflicts of interest. 

Marilynn Larkin, MA, is an award-winning medical writer and editor based in New York City whose work has appeared in numerous publications, including Medscape Medical News and its sister publication MDedge, The Lancet (where she was a contributing editor), and Reuters Health.