Stress and hunger hormones make evening a risky time for binge eating
The late-night urge to snack is something we all encounter from time to time, but new research suggests this phenomenon is the result of riding “hunger hormone” levels and decreasing “satiety (or fullness) hormones” in the evening. More so, the impact of these hormone changes may have an even greater impact on people prone to binge eating or living with binge eating disorder.
The findings, published in the International Journal of Obesity, indicate that stress and being prone to binge eating make late evening a risky time for over-eating. However, it may also provide insight into potential strategies to preempt this behavior.
“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, Ph.D., assistant professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine, and the new study’s first author. “The good news 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,” she adds.
Carnell says the new research was motivated by recent findings that levels of ghrelin, a hormone associated with hunger, can rise in response to stress during the day. Carnell and her team wanted to evaluate how increased stress could affect hunger urges later in the day, especially among those with binge eating disorder.
The team notes that those with binge eating disorder often report overeating in the evenings.
To assess this, the team created an experiment to measure hunger and stress hormones in participants at different times throughout the day.
The research team recruited 32 overweight participants, including 19 men and 13 women. All the participants were between the ages of 18 and 50, and half had been previously diagnosed with binge eating disorder. Roughly half of the participants were African-American.
All participants had body mass indices (BMI) ranging from 28 to 52 but were otherwise healthy.
Throughout the study, the participants would fast for eight hours, then they would receive a liquid meal of 608 calories at either 9 a.m. or 4 p.m. Approximately 130 minutes after the meal, each participant would undergo a standard experimental stress test which included having their facial expressions recorded while submerging their nondominant hand in a bucket of cold water for two minutes.
After this test, the researchers would draw blood from each participant to assess hunger and stress hormone levels. The participants also rated their subjective levels of hunger and fullness on a numeric scale.
Thirty minutes after the stress test, participants were then offered a large assortment of food including three medium pizzas, individual containers of snack chips, cookies, chocolate covered candies, and water.
According to their findings, the research team says that time of day played a big role in hunger levels, with greater baseline self-reported appetite in the evening compared to the morning. The team also noted that levels of peptide YY (a hormone associated with reduced appetite), glucose, and insulin decreased when given a liquid meal later in the day.
Notably, only those with binge eating disorder showed overall lower fullness in the evening. They also had higher initial levels of ghrelin in the evening and lower initial ghrelin levels in the morning compared to the rest of the participants.
Following the stress test, stress levels immediately spiked while hunger levels slowly increased in both the morning and evening. However, ghrelin levels were overall higher in the evening, suggesting that stress may impact hunger more significantly in the evening.