“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.
Susan Carnell is an assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study’s first author.
Carnell, who also conducts research within Johns Hopkins Children’s Center, notes that previous research has shown that levels of ghrelin, a hunger hormone, can rise in response to stress during the daytime.
The researchers were curious how stress might affect hunger urges at later hours—especially among those with binge eating disorder who often overeat in the evenings—and created an experiment to measure participants’ hunger and stress hormones at different times.
For the study, the team recruited 32 overweight participants (19 men and 13 women), 18 to 50 years of age. Half had previously been diagnosed with binge eating disorder, and 47 percent were African-American.
Participants had body mass indices, or BMI, ranging from 28 to 52 and were otherwise healthy.
The study required that each participant fast for eight hours, then receive a liquid meal of 608 calories at either 9 a.m. or 4 p.m.
Some 130 minutes after the meal, each participant then underwent a standard experimental stress test in which a digital camera recorded their facial expressions while their nondominant hand was submerged in a bucket of 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, participants were offered a buffet that consisted of three medium pizzas, individual containers of snack chips, cookies and chocolate covered candies, and water.
The research team found that time of day significantly impacted hunger levels, with greater baseline self-reported appetite in the evening compared with the morning.
The team also saw relatively decreased levels of peptide YY—a hormone linked to reduced appetite, glucose, and insulin levels—in relation to 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, suggesting that stress may impact this hunger hormone more in the evening than in daytime.
Other authors on this paper include C. Grillot of Florida State University; S. Ellis, N. Mehta and A. Geliebter of the Icahn School of Medicine at Mt. Sinai; and J. Holst of the University of Copenhagen.
Gut hormones influence eating and addictive behaviours (2017-12-14)
Effects of smoking and its abstinence on dietary intake and appetite (2016/09/12)
Hormone ghrelin increases the sex drive (2015-05-15)
Mechanism of action of whole milk and its components on glycemic control in healthy young men (2014-10-29)
For more information
International Journal of Obesity
Morning and afternoon appetite and gut hormone responses to meal and stress challenges in obese individuals with and without binge eating disorder
The Johns Hopkins Children’s Center
The Johns Hopkins Medicine
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