Why Do We Overeat in the Evening?
Do you find yourself wandering into the kitchen during the evening hours even if you are not hungry? Do you justify and allow yourself to consume a delicious nighttime snack after a stressful day? A study published in the International Journal of Obesity in 2018 examined evening eating and stress.
The Evening Overeating Experiment
The research included 32 adults, aged 18–50 years, who were overweight. Each subject was asked to participate in two experiments. The first required the subjects to fast for 8 hours before receiving a “liquid meal,” consisting of 608 calories, at 9 a.m.
For the second experiment, participants were again asked to fast for 8 hours, but this time, they consumed the liquid meal at 4 p.m. Around 130 minutes after each meal, the participants all underwent a stress test. This required the subjects to place one hand in a bucket of cold water for 2 minutes, while their facial expressions were recorded.
Participants were offered a food and drink buffet, which consisted of pizza, cookies, chips, candy, and water, 30 minutes after the stress test began. The researchers also took blood samples from the subjects, and these were monitored for levels of the “stress hormone” cortisol, as well as the “hunger hormones” ghrelin and peptide YY (PYY). Subjects were also asked to report their levels of hunger and fullness prior to each experiment. The overall aim of this research was to determine how the time of day affects appetite, and whether stress might play a role.
The Results of the Experiment
Overall, prior to each experiment, participants reported greater hunger and lower fullness in the evening than in the morning. Levels of ghrelin, which is the hormone that stimulates appetite, were found to be higher after consumption of the afternoon meal compared with the morning meal, while levels of PYY, which is a hormone that reduces appetite, were found to be lower in the evening. Looking at the stress test results, the team found that — in both the morning and evening — all subjects experienced a gradual increase in cortisol and ghrelin levels, though levels of these hormones were higher in the afternoon. They say that this finding suggests that stress may have greater influence on ghrelin in the evening than earlier in the day.
Taken together, the researchers believe that their study results indicate that we are more likely to overeat in the evening due to changes in our hunger hormones, and that stress may exacerbate the risk.
The Solution to Nighttime Overeating
Based on the findings of this research, one potential solution to evening eating would be to try to shift your food intake to earlier in the day and to also make a conscious effort to avoid stress exposure during the evening. It may also help to increase personal awareness of potential evening vulnerability to overeating and interactions with stress, as well as taking preventive measures, such as stress-reduction techniques.
Carnell S, Grillot C, Ungredda T, Ellis S, Mehta N, Holst J, Geliebter A. Morning and afternoon appetite and gut hormone responses to meal and stress challenges in obese individuals with and without binge eating disorder. Int J Obes (Lond). 2018 Apr;42(4):841-849. doi: 10.1038/ijo.2017.307. Epub 2017 Dec 12. PMID: 29235554.