We all know that eating later in the day isn’t good for our waistlines, but why? A new study assessed this question by comparing people who ate the same foods — but at different times of day.
“Does the time we eat matter when everything else is kept consistent?” said first author Nina Vujović, a researcher in the division of sleep and circadian disorders at Brigham and Women’s Hospital in Boston.
The answer was yes – eating later in the day will double your chances of being hungrier, according to the study published in the journal Cell Metabolism.
“We found that eating four hours later makes a significant difference to our hunger levels, the way we burn calories after eating, and the way we store fat,” Vujović said.
“Together, these changes may explain why late eating is associated with the increased risk of obesity reported by other studies and provide new biological insights into the underlying mechanisms.”
The study provides support for the concept that circadian rhythm, which influences key physiological functions such as body temperature and heart rate, affects how our bodies absorb fuel, the researchers said.
Research shows that eating later results in “an increase in hunger, affects hormones and also alters gene expression, especially in terms of fat metabolism, with a tendency towards less fat breakdown and more fat deposition,” said Bhanu Prakash. Kolla, a professor of psychiatry and psychology at the Mayo Clinic School of Medicine and a consultant to the Center for Sleep Medicine and the Mayo Division of Addiction Medicine.
While previous studies have linked late eating to weight gain, this study did not measure weight loss and cannot show a causal link, said Kolla, who was not involved in the study. In addition, research has shown that skipping breakfast is linked to obesity, he said.
“So, could these results be a result of skipping breakfast instead of eating late? That’s an effect to consider for this study,” Kolla said.
Conducting the research
The study was small — just 16 overweight or obese people — but carefully designed to rule out other potential causes of weight gain, the authors said.
“While there are other studies investigating why eating late is associated with an increased risk of obesity, this may be the best controlled one, including strict control of the amount, composition and timing of meals, physical activity, sleep, room temperature, and exposure to food. light,” said senior author Frank Scheer, director of the Medical Chronobiology Program in Brigham’s Division of Sleep and Circadian Disorders.
All participants were in good health, with no history of diabetes or shift work, which can affect circadian rhythm, and engaged in regular physical activity. Each person in the study maintained a strict sleep schedule for about three weeks and was given meals prepared at fixed times for three days before the start of the lab experiment.
Participants were then randomized into two groups. One group ate calorie-controlled meals at 8 am, noon and 4 pm, while the other ate the same meals four hours later at noon, 4 pm and 8 pm during the six days reported in the study.
Hunger and appetite data were collected 18 times each, while body fat, temperature and energy expenditure tests were collected on three separate days.
After a break of a few weeks, the same participants reversed the procedure—those who had eaten earlier were switched to the late-eating group and vice versa, using each person as their own control.
More hunger, less fat burned
Results showed that hunger pangs doubled for those on a nighttime eating regimen. People who ate later in the day also reported cravings for starchy and salty foods, meat and, to a lesser extent, cravings for dairy and vegetables.
By looking at blood test results, the researchers were able to see why: Levels of leptin, a hormone that tells us when we feel full, were reduced for late eaters versus early eaters. In comparison, levels of the hormone ghrelin, which increases our appetite, increased.
“What’s new is that our results show that eating late causes an increase in the ratio of ghrelin to leptin on average over the entire 24-hour sleep/wake cycle,” Scheer said. In fact, the study found that the ratio of ghrelin to leptin increased by 34% when meals were eaten later in the day.
“These changes in appetite-regulating hormones dovetail well with the increased hunger and appetite with late eating,” Scheer said.
When participants ate later in the day, they also burned calories at a slower rate than when they ate earlier. Tests of their body fat found changes in genes that would affect how fat is burned or stored, the study found.
“These changes in gene expression would support the growth of adipose tissue by forming more fat cells as well as increasing fat storage,” Scheer said.
It is unknown whether these effects would continue over time or in people currently taking medication for chronic conditions, who were excluded from this study. More studies are needed, the authors said.
Source: CNN Brasil
I am an experienced journalist and writer with a career in the news industry. My focus is on covering Top News stories for World Stock Market, where I provide comprehensive analysis and commentary on markets around the world. I have expertise in writing both long-form articles and shorter pieces that deliver timely, relevant updates to readers.
