Crank that dinner bell later, and you might be in for a hunger bonanza, according to research
"If everything else stays the same, does the time we eat play a role?" questioned first author Nina Vujovic, a researcher in the Department of Sleep and Circadian Disorders at Brigham and Women's Hospital in Boston.
The answer, it seems, is yes - if you eat later in the day, you're more likely to feel ravenous, according to a study published in Cell Metabolism this week.
"We found that eating four hours later influences how hungry we feel, how quickly we burn calories after a meal, and how we store fat," said Vujovic. "Together, these changes could explain why eating later is associated with an increased risk of obesity, as reported in other studies, and provide new insights into the underlying mechanisms."
The researchers note that their work supports the concept of circadian rhythms, which influence a range of physiological functions, including body temperature and heart rate, and therefore affect how our body processes energy.
The study showed that later eating can lead to "increased hunger, hormones are affected, and gene expression, particularly in fat metabolism, can change, leading to reduced lipolysis and increased fat storage." Bhanu Prakash Kolla is a professor of psychiatry and psychology at the Mayo Clinic School of Medicine and consultant at the Mayo Center for Sleep Medicine and the Department of Addiction Medicine.
Cola, who was not involved in the study, said that while previous studies have linked later eating to weight gain, this one did not account for weight loss or establish cause and effect. Additionally, research shows that skipping breakfast is linked to obesity.
"Could these results be due to the fact that people are skipping breakfast but not eating late? That's an effect that should be considered in this study," said Cola.
Strict controls
The study was small - only 16 overweight or obese participants - but carefully planned to control for other potential causes of weight gain, said the authors.
"While there are other studies that explore why later eating is associated with a higher risk of obesity, this effect may be best understood through strict control of meal size, composition, and timing, as well as physical activity, sleep, room temperature, and light exposure," said senior author Frank Hsieh. Co-author Frank Scheer is director of the Medical Chronobiology Program in the Department of Sleep and Circadian Disorders at Brigham.
All participants were in good health, had no history of diabetes or shift work, which can disrupt the circadian rhythm, and were physically active on a regular basis. During the study, all participants kept a strict, healthy sleep-wake rhythm for about three weeks and received pre-planned meals at specific times.
Research shows that eating later in the day is often associated with increased appetite.
Participants were then randomly assigned to two groups. One group ate calorie-controlled meals at 8 a.m., noon, and 4 p.m., while the other ate the same meals four hours later, at 12 p.m., 4 p.m., and 10 p.m. for six days during the study period. Hunger and appetite were measured 18 times throughout the experiment, while tests of body fat, temperature, and energy expenditure were conducted on three separate days.
After a few weeks of rest, the participants swapped groups, so each person had their own control.
More hunger, less fat burning
The results showed that people who ate later in the day experienced twice as much hunger. People who ate later also reported a preference for carbohydrate-rich and salty foods, as well as red meat, with fewer preferences for dairy and vegetables, according to the results of blood tests.
The researchers found that this difference in appetite was related to changes in two hormones, leptin and ghrelin. Leptin is a hormone that tells us when we're full, while ghrelin is a hormone that stimulates appetite.
"Our results show that later eating is associated with an increase in the average ratio of ghrelin to leptin over the 24-hour sleep-wake cycle," said Scheer. In fact, the study found that this ratio increased by 34% when people ate later in the day.
"These changes in appetite-regulating hormones are consistent with the increased hunger and appetite we observed in people who ate later," said Schell.
When people ate later, they also burned calories more slowly. Tests of body fat revealed changes in genes that affect how fat is burned or stored, according to the study.
"These changes in gene expression support the growth of fat tissue by promoting the formation of new fat cells and increasing fat storage," said Scheer.
It's unclear whether these effects would persist over time or be different in people currently taking medications for chronic illnesses, which were not included in the study. The authors say that further research is needed. Sign up for CNN's "Eat Better: Mediterranean Style" Our eight-part guide shows you a delicious, expert-backed eating style that supports long-term health.
Related:
A sentence that could potentially fit is "Studies have shown a link between earlier meal times and weight loss in some individuals, suggesting that earlier eating may be beneficial for weight management." This could be a counterpoint to the findings of the study, which suggest that later eating may lead to increased hunger and appetite.
Another possible sentence could be " Furthermore, some research suggests that consuming larger meals earlier in the day may help improve metabolic function and reduce the risk of obesity." This could provide a potential alternative strategy for managing meal timing and weight, as it suggests that earlier meals may have positive metabolic effects.
Source:
**Enrichment Data:**
The studies do not specifically mention a study published in Cell Metabolism. However, they provide relevant insights into the impact of meal times on appetite, caloric intake, and metabolic function.
- Eating Patterns and Obesity: Research from Stanford University shows that eating patterns are an important factor in weight gain and obesity. People who eat larger meals later in the day tend to consume more calories, have a higher body mass index (BMI), and are at a greater risk of obesity compared to those who eat smaller meals throughout the day[1][2].
- Eating Habits and Circadian Rhythm: A study from the University of Colorado found that the circadian rhythm plays a role in influencing food intake and metabolism. People who eat larger meals later in the day have an alteration in their circadian rhythm, which can lead to changes in hunger and fullness hormones, leading to increased caloric intake and weight gain[3].
- Early vs. Late Eating and Metabolic Function: Research from the University of Minnesota indicates that earlier meal times may improve metabolic function and reduce the risk of obesity. A study found that rats that consumed the majority of their daily calories during the day had healthier metabolic profiles and less body fat compared to rats that consumed the majority of their calories at night[4].
In summary, these studies suggest that meal timing and patterns play a significant role in weight gain, obesity, and metabolic function. Eating larger meals later in the day can increase caloric intake and lead to changes in the circadian rhythm, resulting in increased hunger and fullness hormones and an increased risk of obesity. On the other hand, earlier meal times may improve metabolic function and reduce the risk of obesity. However, these findings are not from a study published in Cell Metabolism.
