April 11, 2024 -- You are what you eat, as the saying goes. But a growing body of evidence indicates that it's not just what and how much you eat that influence your health. How fast and when you eat also play a role.
Research now indicates that these two factors may affect the risk for gastrointestinal problems, obesity, and type 2 diabetes. Because meal timing and speed of consumption are modifiable, they present new opportunities to change behavior to help prevent and perhaps address these conditions.
Not So Fast
Most people are well acquainted with the short-term gastrointestinal effects of eating too quickly, which include indigestion, gas, bloating, and nausea. But regularly eating too fast can cause long-term consequences.
Obtaining a sense of fullness is key to staving off overeating and excess caloric intake. However, it takes approximately 20 minutes for the stomach to alert the brain to feelings of fullness. Eat too quickly and the fullness signaling might not set in until you've consumed more calories than intended. Research links this habit to excess body weight.
The practice also can lead to gastrointestinal diseases over the long term because overeating causes food to remain in the stomach longer, thus prolonging the time that the gastric mucosa, mucous membrane layer of the stomach, is exposed to gastric acids.
A study of 10,893 adults in South Korea reported that those with the fastest eating speed (less than 5 minutes per meal) had a 1.7 times greater likelihood of one kind of gastritis than those with the slowest times (greater than or equal to 15 minutes per meal). Faster eating also was linked to increased risk for prolonged indigestion in a study involving 89 young-adult female military cadets in South Korea with relatively controlled eating patterns.
On the extreme end of the spectrum, researchers who performed an assessment of a competitive speed eater speculated that the observed expanding of the stomach to form a large sac necessary makes speed eaters vulnerable to morbid obesity, gastroparesis, intractable nausea and vomiting, and the need for gastrectomy.
The risk for metabolic changes and eventual development of type 2 diabetes also appears to be linked to how quickly food is consumed.
Given these potential issues, the good news is people can slow the speed at which they eat so they feel full before they overeat.
A 2019 study in which 21 participants were instructed to eat a 600-calorie meal at a "normal" or "slow" pace (6 minutes or 24 minutes) found that the slower group reported feeling fuller while consuming fewer calories.
This approach may not work for all people, however. There's evidence to suggest that tactics to slow down eating may not limit the number of calories people who already overweight or obese consume.
Patients with obesity may physiologically differ in their processing of food, according to Michael Camilleri, MD, consultant in the Division of Gastroenterology and Hepatology at Mayo Clinic in Rochester, Minnesota.
"We have demonstrated that about 20%-25% of people with obesity actually have rapid gastric emptying," he said. "As a result, they don't feel full after they eat a meal and that might impact the total volume of food that they eat before they really feel full."
The Ideal Time to Eat
It's not only the speed at which individuals eat that may influence outcomes but when they take their meals. Research indicates that eating earlier in the day to align meals with the body's circadian rhythms in metabolism offers health benefits.
"The focus would be to eat a meal that syncs during those daytime hours," Collin Popp, PhD, a research scientist at the NYU Grossman School of Medicine in New York, said. "I typically suggest patients have their largest meal in the morning, whether that's a large or medium-sized breakfast, or a big lunch."
A recent study of 2,050 participants found that having the largest meal at lunch protected against obesity, while having it at dinner increased the risk for obesity and led to higher body mass index.
Consuming the majority of calories in meals earlier in the day may have metabolic health benefits, as well.
Time-restricted eating, a form of intermittent fasting, also can improve metabolic health depending on the time of day.
Patients May Benefit From Behavioral Interventions
Patients potentially negatively affected by eating too quickly or at late hours may benefit from adopting behavioral interventions to address these tendencies. To determine if a person is a candidate for such interventions, Popp recommends starting with a simple conversation.
"When I first meet patients, I always ask them to describe to me a typical day for how they eat — when they're eating, what they're eating, the food quality, who are they with — to see if there's social aspects to it. Then try and make the recommendations based on that," said Popp.
