People who are overweight may be at higher risk for overeating in the evening hours, especially when experiencing stress, a new study suggests.
The experiments add to evidence that “hunger hormone” levels rise and hormones that make us feel full decline during evening hours.
The findings also suggest that stress may increase hunger hormone levels more in the evening, and that the impact of hormones on appetite may be greater for people prone to binge eating.
“Our findings suggest that evening is a high-risk time for overeating, especially if you’re stressed and already prone to binge eating,” says Susan Carnell, assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.
“The good news,” she adds, “is that, having this knowledge, people could take steps to reduce their risk of overeating by eating earlier in the day, or finding alternative ways to deal with stress.”
Carnell, lead author of the study, says that previous research showed that levels of ghrelin, a hunger hormone, can rise in response to stress during the daytime.
Curious how stress might affect hunger urges at later hours, especially among those with binge eating disorder who often overeat in the evenings, the researchers created an experiment to measure participants’ hunger and stress hormones at different times.
The research team recruited 32 overweight participants (19 men and 13 women). They were 18 to 50 years old; half had previously been diagnosed with binge eating disorder.
Each participant fasted for eight hours, then received a liquid meal of 608 calories at either 9 a.m. or 4 p.m. Some 130 minutes after the meal, each participant took a standard experimental stress test; a digital camera recorded their facial expressions while their non-dominant hands were submerged in cold water for two minutes.
Researchers drew blood from each participant to measure stress and hunger hormones. The subjects were also asked to rate their subjective levels of hunger and fullness on a numeric scale.
Thirty minutes after the start of the stress test—about 11:40 am or 6:40 pm, depending on the group—participants were offered a buffet that consisted of three medium pizzas, individual containers of snack chips, cookies, and chocolate-covered candies, and water.
The time of day significantly affected hunger levels, with greater baseline self-reported appetite in the evening than the morning. The researchers also saw relatively decreased levels of peptide YY, a hormone linked to reduced appetite, glucose, and insulin levels, after a liquid meal later in the day.
Carnell says only those with binge eating disorder showed lower overall fullness in the evening. This group also had higher initial levels of ghrelin in the evening and lower initial ghrelin levels in the morning, when compared with those without binge eating disorder.
After the stress test, stress levels spiked and hunger levels rose slowly in all participants in both the morning and evening, but there were overall higher levels of ghrelin in the evening. That suggests that stress may impact this hunger hormone more in the evening than in daytime.
The researchers report their findings in the International Journal of Obesity.
Other members of the research team were from Florida State University, Icahn School of Medicine at Mount Sinai, and the University of Copenhagen. The National Institute of Diabetes and Digestive and Kidney Diseases paid for the research.
Source: Johns Hopkins University