It's common sense that eating late can lead to weight gain. However, a recent study has shed some light on why this occurs.
According to researchers, eating late has a profound impact on the appetite-regulating hormones ghrelin and leptin.
The research, published in Cell Metabolism, found that "eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat."
The study suggested that late night eating may slow fat burning and increase fat storage. Eating late slows metabolism, resulting in fewer calories burned, while simultaneously stimulating ghrelin "the hunger hormone" which leads to food cravings, especially for salty and starchy foods. The study measured the differences between a more traditional eating pattern (breakfast at 8 AM, lunch at noon, and dinner at 5:30 PM), with a late eating pattern (no breakfast, lunch at noon, dinner at 5:30 PM, and a late-night meal at 9:30 PM).
The results verified what many late-night snackers have experienced: late eating doubled the likelihood of feeling hungry and significantly increased how much a person wanted to eat.
Night eating is a concern because research has found meal timing interacts with our circadian rhythm. Late night eating has been found to disrupt this rhythm, and therefore influence our sleep-wake cycles. It is well-established that abnormal circadian rhythms (and chronic sleep problems) are associated with poor health and metabolic disorders. For example, night shift workers have been shown to have a high risk of obesity, type 2 diabetes, and cardiovascular disease.
Research has shown late eating also can affect the health of school-aged children, and that meal timing is a factor in obesity. School-age children were found to have double the chances of being overweight or obese and had higher inflammatory markers and more circadian-related disturbances when eating after 10PM.
Here are some reasons why you may feel hungry after bedtime: skipping breakfast, stress eating, and alcohol consumption (lowering inhibitions).
As the science shows, you should try to avoid eating at night. Late-night snacking affects your metabolism, adds calories you likely don't need to your diet, and can make you hungry and affect your meal choices the next day, increasing your risk of obesity.
If the hunger is from boredom or drinking alcohol, try distracting yourself. The hunger may pass, giving you the chance to wake up with an empty stomach and hungry for breakfast, which will help you start a proper circadian rhythm eating pattern.
References
Boege, Hedda L, et al. "Circadian rhythms and meal timing: impact on energy balance and body weight." Curr Opin Biotechnol. August 2021, https://pubmed.ncbi.nlm.nih.gov/32998085/
Davis, Rochelle, et al. "The Impact of Meal Timing on Risk of Weight Gain and Development of Obesity: a Review of the Current Evidence and Opportunities for Dietary Intervention." Curr Diab Rep. April 2022, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9010393/
Malin, Steven K. "Timing Is Everything, Right? Meal Impact on Circadian Related Health." JCEM. November 2020, https://academic.oup.com/jcem/article/106/2/e1050/5952711
MartÃnez-Lozano, Nuria, et al. "Late Eating Is Associated with Obesity, Inflammatory Markers and Circadian-Related Disturbances in School-Aged Children." Nutrients. September 2020, https://www.mdpi.com/2072-6643/12/9/2881/htm
Nolan, Laurence J, Geliebter, Allan. "Food addiction is associated with night eating severity." Appetite. March 2016, https://pubmed.ncbi.nlm.nih.gov/26724725/
Vujović, Nina, et al. "Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity." Cell Metabolism. October 2022, https://www.cell.com/cell-metabolism/fulltext/S1550-4131(22)00397-7
Wehrens, Sophie M.T., et al. "Meal Timing Regulates the Humans Circadian System." Curr Biol. June 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5483233/
"Eating late increases hunger, decreases calories burned, and changes fat tissue." Brigham and Women's Hospital. October 2022, https://www.sciencedaily.com/releases/2022/10/221004121928.htm
Adapted from: Night Eating Increases Appetite - Life Extension