Study explains what triggers those late-night snack cravings

April 30, 2013, Oregon Health & Science University

A study published in the most recent version of the journal Obesity found that the body's internal clock, the circadian system, increases hunger and cravings for sweet, starchy and salty foods in the evenings. While the urge to consume more in the evening may have helped our ancestors store energy to survive longer in times of food scarcity, in the current environment of high-calorie food, those late night snacks may result in significant weight gain.

"Of course, there are many factors that affect weight gain, principally and , 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 because it intensifies hunger at night," said Steven Shea, Ph.D., director for the Center for Research on Occupational and Environmental Toxicology at Oregon Health & Science University and 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."

Indeed, eating a lot in the evening can be counterproductive since the human body handles nutrients differently depending on the time of day. For example, sugar tolerance is impaired in the evening. Additionally, consuming more calories in the evening predisposes people to more energy storage; we simply don't expend as much energy after an evening meal in comparison to morning meals.

Dr. Steven Shea, Oregon Health and Science University, discusses a study that he co-authored, which was published in the most recent version of the journal Obesity. The study found that the body's internal clock, the circadian system, increases hunger and cravings for sweet, starchy and salty foods in the evenings. Consuming more calories in the evening predisposes people to more energy storage, which can lead to weight gain. Credit: OHSU

Furthermore, artificial light enables people to stay up later than they probably should and often people 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 ."

"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."

Conducted by Shea and two Boston-area researchers, Frank Scheer, Ph.D. and Christopher Morris, Ph.D. of Brigham and Women's Hospital and Harvard Medical School, the study examined the appetite and food preference of 12 healthy non-obese adults throughout a 13-day laboratory stay in very dim light in which all behaviors were scheduled, including timing of meals and sleep. Dr. Scheer, first author on the study, explained that "by the end of this long protocol, all of the participants' meals and activities were spaced evenly across the day and night, allowing examination of the true internal circadian effects on appetite, while controlling for other effects on appetite including the amount of food recently consumed."

The researchers found that the internal circadian system regulated , with participants feeling the least hungry in the morning (8 a.m.) and most hungry in the evening (8 p.m.). Similar rhythms were found in appetite for types of food, such as sweet, starchy and salty, and the estimate of how much food participants could eat. The study concludes that the internal circadian system causes an evening peak in appetite that may promote 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 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".

Explore further: Night owls at risk for weight gain and bad diet

Related Stories

Night owls at risk for weight gain and bad diet

May 4, 2011
Staying up late every night and sleeping in is a habit that could put you at risk for gaining weight. People who go to bed late and sleep late eat more calories in the evening, more fast food, fewer fruits and vegetables ...

Less sleep leads to more eating, more weight gain, research says

March 11, 2013
Sleeping just five hours a night over a workweek and having unlimited access to food caused participants in a new study led by the University of Colorado Boulder to gain nearly two pounds of weight.

Eat a protein-rich breakfast to reduce food cravings, prevent overeating later, researcher finds

May 19, 2011
A University of Missouri researcher has found that eating a healthy breakfast, especially one high in protein, increases satiety and reduces hunger throughout the day. In addition, using functional magnetic resonance imaging ...

Blood pressure's internally driven daily rhythm unlikely to be linked to morning heart attacks

April 7, 2011
The internally-driven daily cycle of blood pressure changes doesn't appear to be linked to the known increase in morning heart attacks, according to a study in Circulation Research: Journal of the American Heart Association.

Recommended for you

Where you live may influence whether you are overweight, study finds

January 23, 2018
The old real estate adage of "location, location, location" may also apply to obesity.

Evening hours may pose higher risk for overeating, especially when under stress, study finds

January 16, 2018
Experiments with a small group of overweight men and women have added to evidence that "hunger hormone" levels rise and "satiety (or fullness) hormone" levels decrease in the evening. The findings also suggest that stress ...

Bariatric surgery prolongs lifespan in obese

January 16, 2018
Obese, middle-age men and women who had bariatric surgery have half the death rate of those who had traditional medical treatment over a 10-year period, reports a study that answers questions about the long-term risk of the ...

Sugar-sweetened drinks linked to overweight and obesity in children, adults: Analysis of new studies

December 23, 2017
A new review of the latest evidence on sugar-sweetened beverages (SSBs)- which includes 30 new studies published between 2013 and 2015 (and none of them industry sponsored) - concludes that SSB consumption is associated with ...

As income rises, women get slimmer—but not men

December 21, 2017
(HealthDay)—A comprehensive survey on the widening American waistline finds that as paychecks get bigger, women's average weight tends to drop.

Policy and early intervention can curb obesity rates

December 18, 2017
More information and emphasis on dietary lifestyle changes that prevent obesity, and its comorbidities, have not reduced the rise in obesity in U.S. adults and adolescents, according to a recent study in the New England Journal ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.