Then we ate them.
Posted on 10/11/2010 2:58:19 PM PDT by decimon
COLUMBUS, Ohio – Persistent exposure to light at night may lead to weight gain, even without changing physical activity or eating more food, according to new research in mice.
Researchers found that mice exposed to a relatively dim light at night over eight weeks had a body mass gain that was about 50 percent more than other mice that lived in a standard light-dark cycle.
"Although there were no differences in activity levels or daily consumption of food, the mice that lived with light at night were getting fatter than the others," said Laura Fonken, lead author of the study and a doctoral student in neuroscience at Ohio State University.
The study appears this week in the online early edition of the Proceedings of the National Academy of Sciences.
If the mice are not less active or eating more, what's causing the bigger weight gain? Results suggest that mice living with light at night eat at times they normally wouldn't.
In one study, mice exposed to light at night – but that had food availability restricted to normal eating times – gained no more weight than did mice in a normal light-dark cycle.
"Something about light at night was making the mice in our study want to eat at the wrong times to properly metabolize their food," said Randy Nelson, co-author of the study and professor of neuroscience and psychology at Ohio State.
If these results are confirmed in humans, it would suggest that late-night eating might be a particular risk factor for obesity, Nelson said.
In one study, mice were housed in one of three conditions: 24 hours of constant light, a standard light-dark cycle (16 hours of light at 150 lux, 8 hours of dark), or 16 hours of daylight and 8 hours of dim light (about 5 lux of light).
The researchers measured how much food the mice ate each day. They also measured how much they moved around their cages each day through an infrared beam crossing system. Body mass was calculated each week.
Results showed that, compared to mice in the standard light-dark cycle, those in dim light at night showed significantly higher increases in body mass, beginning in the first week of the study and continuing throughout.
By the end of the experiment, light-at-night mice had gained about 12 grams of body mass, compared to 8 grams for those in the standard light-dark cycle. (Mice in constant bright light also gained more than those in the standard light-dark cycle, but Nelson said the dim light-at-night mice were better comparisons to the light exposure that humans generally get.)
The dim light-at-night mice also showed higher levels of epididymal fat, and impaired glucose tolerance – a marker of pre-diabetes.
Although the dim light-at-night mice didn't eat more than others, they did change when they ate, results showed. These mice are nocturnal, so they would normally eat substantially more food at night. However, the dim light-at-night mice ate 55 percent of their food during the daylight hours, compared to only 36 percent in the mice living in a standard light-dark cycle.
Since the timing of eating seemed significant, the researchers did a second study, similar to the first, with one important difference: instead of having food freely available at all times, food availability was restricted to either the times when mice would normally be active or when they would normally be at rest.
In this experiment, mice exposed to the dim light at night did not have a greater gain in body mass than did the others when their food was restricted to times when they normally would be active.
"When we restricted their food intake to times when they would normally eat, we didn't see the weight gain," Fonken said. "This further adds to the evidence that the timing of eating is critical to weight gain."
The findings showed that levels of corticosterone, a stress hormone, were not significantly different in dim light-at-night mice compared to those living in a standard light-dark cycle.
That's important because corticosterone has been linked to changes in metabolism, Fonken said. This shows there doesn't have to be changes in corticosterone levels to have changes in metabolism in the mice.
So how does light at night lead to changes in metabolism? The researchers believe the light could disrupt levels of the hormone melatonin, which is involved in metabolism. In addition, it may disrupt the expression of clock genes, which help control when animals feed and when they are active.
Overall, the findings show another possible reason for the obesity epidemic in Western countries.
"Light at night is an environmental factor that may be contributing to the obesity epidemic in ways that people don't expect," Nelson said. "Societal obesity is correlated with a number of factors including the extent of light exposure at night."
For example, researchers have identified prolonged computer use and television viewing as obesity risk factors, but have focused on how they are associated with a lack of physical activity.
"It may be that people who use the computer and watch the TV a lot at night may be eating at the wrong times, disrupting their metabolism," Nelson said. "Clearly, maintaining body weight requires keeping caloric intake low and physical activity high, but this environmental factor may explain why some people who maintain good energy balance still gain weight."
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Other co-authors were Joanna Workman, James Walton, Zachary Weil, and John Morris, all of Ohio State; and Abraham Haim, of the University of Haifa, Mount Carmel, in Israel.
The research was supported by the National Science Foundation and the U.S.-Israel Binational Science Foundation.
Natural foods, such as bananas, apples, etc, contain complex carbohydrates, which are metabolized much differently than simple sugars. Insult? That’s on you in your interpretation.
Complex carbohydrates are not sugars.
Starch isn’t sugar.
Um, when one is digging themselves into a hole, one should really stop digging. You’re making the hole deeper. Do some research on starches and complex carbs and get back to me. Pay careful attention to how the body metabolizes starches and complex carbohydrates.
Then we ate them.
Yeah, that's the ticket.
(That, and FReeping till the wee hours too often.)
Cheers!
Fruits contain both complex carbohydrates and simple sugars (which make them sweet.)
Vegetables, like beans and potatoes, contain complex carbs...they are not particularly sweet.
An apple has both complex carbs, simple sugar, plus cellulose (which makes it crunchy.)
All of the above substances contain carbon, oxygen and hydrogen, they are similar in that respect, and in chemical formula, but they are not the same thing.
The complex carbs and cellulose slow down the digestion of the apple, but the sugar (whatever version) is the first to enter the blood stream.
I stand by my original position which opposes yours, SUGAR IS SUGAR.
By the way, I did that research over 40 years ago in high school, I assumed you did too. I’m pretty sure the facts remain the same.
Well...black garments are slimming...
Actually, the facts have not remained the same, which if you’d take the time to actually update your antiquated knowledge you’d, by now, know this. Sugar is not sugar is not sugar, and there are complex sugar molecules and simple sugar molecules, and they are not metabolized equally in the digestion process. Eating a serving of applie pie versus eating an equivalent serving of an apple doesn’t result in the same metabolic breakdown of the sugars involved. The sugars that are involved in soda is not the same sugars that are involved with natural orange juice. My information is recent, not 40 years old.
*In one study, mice exposed to light at night – but that had food availability restricted to normal eating times – gained no more weight than did mice in a normal light-dark cycle.*
Restricted diet = no weight gain...what a concept. Simple, take in more calories than you burn = weight gain, no matter what time of day or night you eat.
Gee, you got me on that one.
I'll name some of the common simple sugars, sucrose, fructose, lactose, dextrose, which are found in foods we normally eat.
But I just can't seem to find these "complex sugars" occurring in foods, that you refer to. I guess I'll have to rely on you to identify some of them by name.
Thank you so much.
High fructose corn syrup, sucrose, fructose...all sugars, all equally fattening. OJ is just as fattening as soda.
My information is recent
You haven't given any information, just rhetoric.
I like the way you think.
>>I just can't seem to find these "complex sugars" occurring in foods, that you refer to. I guess I'll have to rely on you to identify some of them by name.<<
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Still looking I see. No luck huh?
Maybe if you google "glycemic index foods" you'll get the information you're looking for.
Enjoy!
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