Posted on 01/24/2012 1:00:12 PM PST by DeoVindiceSicSemperTyrannis
Not just the eating but also the actual position of “couch potatoes” is harmful, new research shows.
It has been known for some time that people who watch hours of TV a day tend to be at higher risk of becoming overweight or obese. The connection was thought to be because of munching junk food while watching. But Tel Aviv University researchers have found that not just the eating but also the actual position of “couch potatoes” is harmful.
Being stretched out in front of the TV is considered to be “active inactivity” and causes viewers to gain weight.
Such inactivity actually encourages the body to create new fat in fat cells, says Prof. Amit Gefen of the department of biomedical engineering. Along with his doctoral student, Naama Shoham, Gefen has shown that preadipocyte cells – the precursors to fat cells – turn into fat cells faster and produce even more fat when subject to prolonged periods of “mechanical stretching loads” – the kind of weight we put on our body tissues when we sit or lie down.
The research, published recently in The American Journal of Physiology – Cell Physiology, demonstrates another damaging effect of a modern, sedentary lifestyle. “Obesity is more than just an imbalance of calories,” Gefen notes. “Cells themselves are also responsive to their mechanical environment.
Fat cells produce more triglycerides, and at a faster rate, when exposed to static stretching.”
Gefen, who investigates chronic wounds that plague bedridden or wheelchair-bound patients, says that muscle atrophy is a common side effect of prolonged inactivity.
Studying MRI images of the muscle tissue of patients paralyzed by spinal cord injuries, he noticed that over time, lines of fat cells invade major muscles. This discovery led to an investigation into how mechanical load – the amount of force placed on a particular area occupied by cells – could be encouraging fat tissue to expand.
In the lab, the researchers stimulated preadipocytes with glucose or insulin to differentiate them into fat cells. Then they placed individual cells in a cellstretching device, attaching them to a flexible, elastic substrate.
The cells were stretched consistently for long periods of time, representing extended periods of sitting or lying down, while a control group of cells was not. Tracking the cultures over time, the researchers noted the development of lipid droplets in both the test and control groups of cells.
After just two weeks of consistent stretching, the test group developed significantly more – and larger – lipid droplets. By the time the cells reached maturity, the cultures that had been mechanically stretched had developed 50 percent more fat than the control culture. They were, in effect, fatter by half again.
According to Gefen, this is the first study that looks at fat cells as they develop, taking into account the impact of sustained mechanical loading on cell differentiation. “There are various ways that cells can sense mechanical loading, which helps them to measure their environment and triggers various chemical processes,” he says. “It appears that long periods of static mechanical loading and stretching, due to the weight of the body when sitting or lying, has an impact on increasing lipid production.” The evidence indicates that we need to take our cells’ mechanical environment into account and pay attention to calories consumed and burned, Gefen suggests. Although there are extreme cases, such as people confined to wheelchairs or beds due to medical conditions, many of us live too sedentary a lifestyle, spending most of the day behind a desk. Even someone with healthy diet and exercise habits will be negatively impacted by long periods of inactivity.
The researchers will now investigate how long a period of time a person can sit or lie down without the mechanical load becoming a factor in fat production. But in the meantime, it certainly can’t hurt to get up and take an occasional stroll, he suggests.
WHITE CELL ‘SELECTORS’
The white blood cells that fight disease and help our bodies heal are sent to sites of infection or injury by “exit signs” – chemical signals that tell them where to pass through the blood vessel walls and into the underlying tissue. New research at the Weizmann Institute of Science that appeared online recently in Nature Immunology shows how cells lining blood vessel walls may act as “selectors” by hiding signals where only certain “educated” white blood cells find them.
In previous studies, Prof. Ronen Alon and his team in the Rehovot institute’s immunology department had found that near sites of inflammation, white blood cells rapidly crawl along the inner lining of the blood vessels with tens of tiny “legs” that grip the surface tightly, feeling their way toward the exit sign. These signs consist of migration-promoting molecules called chemokines, which endothelial cells lining the blood vessels display on their outer surfaces like flashing lights.
In the new study, Alon and his team found that not all chemokine signals produced by endothelial cells are on display.
They observed the recruitment of subsets of immune cells called effector cells that act as the “special forces” of the immune system. They receive training in the lymph nodes, where they learn to identify a particular newly-invading pathogen and then return to the bloodstream on a search-and-destroy mission. Like the other white blood cells, effector cells crawled on tiny appendages along the lining of inflamed blood vessels near the site of pathogen entry, but rather than sensing surface chemokines, they used their legs to reach into the endothelial cells in search of the migration-promoting chemokines.
As opposed to the external exit signs, these chemokines were held in tiny vesicles inside the inflamed endothelial cell walls. The effector cells paused in the place where several cells met, inserting their legs through the walls of several endothelial cells at once to trap chemokines as they were released from vesicles at the endothelial cell membrane.
Once they obtained the right chemokine directives, the immune cells were quickly ushered out through the blood vessel walls toward their final destination.
The researchers think that keeping the chemokines inside the endothelial cells ensures that these vital signals will be safe from getting washed away in the blood or eaten by various enzymes, while at the same time guaranteeing that only those effector cells with special training to find the signals will pass through.
“We are now seeing that the blood vessel endothelium is much more than just a passive, sticky barrier; It actively selects which recruited cells actually cross the barrier and which will not,” says Alon. The endothelial cells seem to play an active role in showing the immune cells the right way out, though we’re not sure exactly how. Moreover, we think that tumors near blood vessels might exploit these trafficking rules for their benefit by putting the endothelial cells in a quiescent state or making the endothelium produce the “wrong” chemokines. Thus, immune cells capable of destroying these tumors will not be able to exit the blood and navigate to the tumor site, while other immune cells that aid in cancer growth will.”
I used to know someone who swore that if you ate your meals while standing up, you would get fat legs.
(Think about that. Yeah, I know.)
Maybe there’s something to that after all... :-)
From the Article: “It has been known for some time that people who watch hours of TV a day tend to be at higher risk of becoming overweight or obese, and stupid.”
That is more like it.
Does that mean that reading for hours a day tends to make people fat also?
Your post interupted my “post” button ... which is good because ... MY comment is, with this election year, I’ve become a FR Potato
Sitting is the new smoking.
Gain weight without eating?
The Law of Conservation of Mass says that’s impossible.
I watch a lot of TV at night, so this isn’t good for me I’m sure.
OSMOSIS!
You get the calories from watching cooking shows, restaurant, soft drink & beer commercials.
Hadn’t thought of it that way. Right on the mark, however don’t find myself as a FR potato getting obese, or stupid as do Couch Potatoes in front of a Leftist loaded television program.
Television anymore IMO is like a pistol that shoots Leftism into our brains. FR is like Kevlar between me and television.
We need warning labels on sofas and a Federal tax on “luxury chairs”. Then we need to haul La-Z-Boy’s CEO in front of Congress and get him to admit that he purposely made the chairs addictive and directed advertisements toward children. Then there needs to be a class action lawsuit for billions of dollars in damages, with the money going toward health care. It’s for the children.
Does this apply to “fooling around” positions too?
What about sleeping? It’s prettymuch the same position.
What about sleeping? It’s pretty much the same position.
I dunno, rock ... there’s a LOT of popcorn to eat and I’m an old fashioned, REAL butter and a sprinkle of salt man.
Inactivity slows the body’s metabolism.....duh! Assuming normal activity, a person could probably consume 1500 calories, but a person who sits on the couch probably doesn’t burn much more than their Basal Metabolic Rate, which is more in the 1000-1100 range. And of course not eating at all, will put the body in “starvation mode”, which will tend to conserve the fat stores, at the expense of muscle.
And it probably happens that if a person is getting overweight anyway, he has already been stuffing his fat cells with dietary fat. When those cells reach a certain repleteness, the formation of new cells from fat stem cells is stimulated. Sitting on one’s ass in front of a TV and having one’s metabolism decrease results in an additional amount of unburned nutrient requiring storage. This would be sufficient to trigger the formation of new fat cells to accommodate the storage.
Popcorn at my age is just necessary roughage. ;)
Exactly. They will be outlawing overstuffed anything, and we will be buying the likes of park benches for our family rooms.
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