A small study suggests that eating all of your meals earlier in the day may suppress hunger and boost fat reduction.
In recent years, a growing number of people are trying intermittent fasting as a strategy to lose weight.
Intermittent fasting is a term used to describe several eating patterns in which people cycle between periods of fasting for 12 hours or more and periods of eating.
Early time-restricted feeding is one type of intermittent fasting in which people eat all of their meals during the morning and early afternoon before fasting for the rest of the day.
According to a new study published in the journal Obesity, early time-restricted feeding may help curb appetite and promote fat burning.
“Prior to this study, we had evidence that both intermittent fasting and eating earlier in the day help with weight loss, but we didn’t know why they seem to help,” Courtney Peterson, PhD, lead investigator of the study and assistant professor in the department of nutrition sciences at the University of Alabama at Birmingham, told Healthline.
“The main goal of this study was to learn whether these meal-timing strategies help with weight loss by helping people burn more calories, by lowering their appetite, or both,” she said.
To conduct this study, Peterson’s research team enrolled 11 people who had good general health but were considered overweight, with a body mass index between 25 and 35.
Each participant tried two meal-timing schedules for four days each. Participants ate the same types and amounts of food while following each schedule.
On the early time-restricted feeding schedule, participants ate all of their meals between 8 a.m. and 2 p.m. each day. On the comparison schedule, participants ate their meals between 8 a.m. and 8 p.m.
The researchers found that when participants ate all of their meals between 8 a.m. and 2 p.m., it had no effect on the number of calories they burned — but it did appear to reduce their appetite.
“What we found is that the hunger hormone, ghrelin, was lower in the morning and tended to be lower in the evening [when people followed the early time-restricted feeding schedule],” Peterson said.
“We also found that the desire to eat was lower when people tried early time-restricted feeding, and the only time of day when they were hungrier than the comparison schedule was right before bedtime, around 10:30 at night,” she continued.
Early time-restricted feeding also appeared to increase the amount of fat participants burned over a 24-hour period.
Although more research is needed, these findings suggest that coordinating mealtimes with the body’s circadian rhythm might help curb appetite and support weight loss.
“Data suggests that you have this internal biological clock that makes you better at doing different things at different times of the day, and there are a bunch of metabolic processes that are a little more efficient in the morning,” Peterson said.
To learn more about the potential effects of early time-restricted feeding, Peterson’s team is conducting ongoing research.
In the meantime, she suggests that many people might find it easier to follow a meal-timing schedule with a larger eating window than the specific schedule they studied.
“We were trying to take an eating schedule that we thought would maximize the benefits, so we tested six-hour eating periods with 18 hours of daily fasting,” she said.
“But the data that we have from studies in my lab and other peoples’ labs suggests that 8 to 10 hours is a better target for many people to aim for,” she continued.
Some people might find early time-restricted feeding helpful for managing their appetite or weight, but experts warn it’s not the right approach for everyone.
“Athletes or anyone who is fairly active may have a hard time with this, depending on when they eat and exercise,” Liz Weinandy, MPH, RDN, LD, lead outpatient dietitian in the department of nutrition services at Ohio State University Wexner Medical Center, told Healthline.
“Other potential barriers would be if a person has a condition that requires them to eat more frequently, like diabetes,” she continued.
People who are pregnant or managing medical conditions such as cancer may also find it difficult to meet their nutritional needs while only eating during short windows of time.
Intermittent fasting may make it harder to partake in meals with family members and friends or navigate social situations that involve food.
“This style of eating may also lead to an unhealthy relationship with food,” Caroline West Passerrello, MS, RDN, LDN, a registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics, warned.
“Therefore, anyone with a history or an eating disorder should avoid this approach,” she said.
Before they try intermittent fasting, Passerrello encourages people to speak with a registered dietitian.
When her clients express interest in intermittent fasting, Passerrello advises them to reflect on their goals and motivations for trying it. She also counsels them to consider the changes they’ll need to make to their daily routines to accommodate an intermittent fasting schedule.
Weinandy advises interested clients to start with an eating window of 12 to 14 hours before trying more restrictive fasting schedules.
She also encourages people to avoid skipping breakfast and pay close attention to how they feel while fasting.
If someone develops signs of low blood sugar while fasting, it may not be the best approach for them.
Some people may also eat more during their eating windows to try to limit hunger later on, which can potentially lead to weight gain.
“A better approach for this group is to go back to smaller, frequent meals and snacks,” Weinandy said.