When it comes to losing weight, how much you eat likely matters more than the timing of your meals, according to study Published Wednesday in the Journal of the American Heart Association.
Researchers at Johns Hopkins University asked 547 people to record the size and timing of their meals in a mobile app every day for six months. The scientists then looked at how much the participants weighed over the course of about six years — more than five years before they began recording their meals and about six months afterward — using electronic health records.
The study divided the recorded meals into three size categories: a small meal contained less than 500 calories, medium meals ranged from 500 to 1,000 calories, and large meals consisted of more than 1,000 calories. Overall, the results showed that the participants who ate the largest number of large and medium meals gained weight over the course of six years, while those who ate the fewest meals lost weight.
This is consistent with the long-standing and well-understood rule Eat fewer calories Contributes to weight loss.
Researchers did not find a link between weight change and the practice of limiting food intake for a specific period of time — often referred to as intermittent fasting. Nor did they find an association between weight change and the timing of a person’s first meal after waking up or their last meal or snack before bed.
“This study shows that changing the timing of eating will not prevent slow weight gain over many years—and perhaps the most effective strategy is to really watch how much you eat, and eat fewer large meals and smaller meals,” said Dr. Wendy Bennett, study author and assistant professor at Johns Hopkins Medicine.
The study included people of different weights, including those who were overweight or obese. The observed changes in weight were generally small, although people who ate an extra daily meal experienced less than 1 pound of extra weight gain per year, on average, compared to people who didn’t eat that extra meal.
“The effect is so small, I wouldn’t tell anyone to change what they’re doing,” said Courtney Peterson, an associate professor of nutritional sciences at the University of Alabama at Birmingham who was not involved in the research.
Still, Bennett said her study provides evidence that meal size restriction can be effective for weight loss, even after adjusting for people’s baseline weights. (People who weigh more tend to have an easier time gaining or losing weight.)
She also notes that the average person gains 1 or 2 pounds per year, which can lead to significant weight gain over time. Eating fewer large meals and more small meals can “prevent this slow creep in weight gain,” Bennett said.
But Peterson said she doesn’t see the study as “a jab” when it comes to determining the best weight loss strategy.
Other research has found that the timing of a person’s first meal of the day can matter: A study published in October found that Eat early in the day It may contribute to weight loss, possibly because it helps people burn calories or feel full throughout the day.
On average, participants in Bennett’s study ate their meals within an 11.5-hour window, with the first meal less than two hours after waking up and the last about four hours before bed.
In order to best test whether intermittent fasting can help with weight loss, Peterson said, researchers have to compare people who limit their eating within a specific window to those who aren’t in a controlled trial.
Previous studies with this type of design have produced mixed results. Some Research He suggests that fasting every other day, or restricting calories to two days per week, can help people with obesity lose weight. But other studies have found Restricting food intake to specific time periods does not reduce body weight any more than restricting daily caloric intake.
“Time-restricted eating can be really beneficial, I think, when it helps people restrict calories,” Bennett said. “We already know that calorie restriction is the most effective weight loss strategy.”
Peterson also confirmed that The nutritional quality of a person’s diet It affects weight gain or loss. consume a lot highly processed foods Such as hot dogs, chips or soda can contribute to weight gain, while diets based on vegetables and whole grains may help with weight loss.
“Some of our best data in humans suggest that diet quality is probably more important than meal timing,” Peterson said.