May 1, 2013
Late Night Snack Cravings Linked To Internal Circadian Rhythm
[ Watch the Video: OHSU´s Dr. Steven Shea Discusses His Research ]
Peter Suciu for redOrbit.com — Your Universe Online
The study, which was published in the journal Obesity, found that the body´s internal clock — known as the circadian system — could increase hunger and cravings for sweet, starchy and salty foods in the evening. In other words, those ads on TV are only partially to blame.
These cravings may have helped people in times when food was scarce and our ancestors may have had the cravings to store energy. However in an era when high-calorie food is all around us, the result of those late night snacks could result in significant weight gain, as eating a lot in the evening can be counterproductive since the human body actually handles nutrients differently throughout the day.
“Of course, there are many factors that affect weight gain, principally diet and exercise, but the time of eating also has an effect. We found with this study that the internal circadian system also likely plays a role in today´s obesity epidemic because it intensifies hunger at night,” said Steven Shea, Ph.D., senior author on the study. “People who eat a lot in the evening, especially high-calorie foods and beverages, are more likely to be overweight or obese.”
Shea is director for the Center for Research on Occupational and Environmental Toxicology (CROET) at Oregon Health & Science University. His research at CROET focuses on the basic and applied research that helps workers stay healthy. CROET´s mission is to promote health, and prevent disease and disability among working Oregonians and their families.
The research has shown that as the human body handles nutrients differently at various times during the day, consuming more calories in the evening is counterproductive as humans don´t typically expend as much energy after an evening meal in comparison to morning and mid-day meals. Additionally, factors such as artificial light enable people to stay up later than they should, and as a result they don´t get enough sleep.
“If you stay up later, during a time when you´re hungrier for high-calorie foods, you´re more likely to eat during that time,” Shea said. “You then store energy and get less sleep, both of which contribute to weight gain.”
The research, which was conducted by Shea along with two Boston-area researchers, Frank Scheer, Ph.D. and Christoper Morris, Ph.D. of Brigham and Women´s Hospital and Harvard Medical School, examined the appetite and food preference of 13 healthy non-obese adults throughout a 13-day laboratory stay in very dim light. During the study all behavior was scheduled, including time of meals and even sleep. The researchers found that the internal circadian system regulated hunger, with participants feeling the least hungry in the morning and the most hungry in the evening. The study further concludes that the internal body clock caused an evening peak in appetite that may promote people to eat larger, higher-calorie meals before the fasting period necessitated by sleep.
“Our study suggests that because of the internal circadian regulation of appetite, we have a natural tendency to skip breakfast in favor of larger meals in the evening. This pattern of food intake across the day is exactly what Sumo wrestlers do to gain weight.” said Steven Shea. “So, it seems likely that the internal circadian system helps with efficient food storage. While this may have been valuable throughout evolution, nowadays it is likely to contribute to the national epidemic of obesity.”
As a result of the findings Shea suggests that those larger meals should then be earlier in the evening.
“If weight loss is a goal, it´s probably better to eat your larger, higher-calorie meals earlier in the day,” said Shea. “Knowing how your body operates will help you make better choices. Going to bed earlier, getting enough sleep and choosing lower-calorie foods rather than higher-calorie foods in the evening can all help with weight loss.”