In the buffet of reasons for why Americans are getting fatter, researchers are piling more evidence on the plate for one still-controversial cause: a virus. New research announced Monday found that when human stem cells — the blank slate of the cell world — were exposed to a common virus they turned into fat cells. They didn't just change, they stored fat, too.
While this may be a guilt-free explanation for putting on pounds, it doesn't explain all or even most of America's growing obesity problem. But it adds to other recent evidence that blames expanding waistlines on more than just super-sized appetites and underused muscles. For several years, researchers have looked at a possible link between obesity and this common virus, called adenovirus-36, from a family of viruses that cause colds and pinkeye in people. They had already found that a higher percentage of fat people had been infected with the virus than nonfat people. They had exposed animals to the virus and got them to fatten up and even found a a gene in the virus that causes animals to get obese.
But ethical restraints kept researchers from exposing people to the virus to see what happens. So they did what would be considered the next best thing, said Nikhil Dhurandhar, who headed the research at the Pennington Biomedical Research Center in the Louisiana State University system.
They took fat tissue from people who had liposuction, removed adult stem cells from the tissue and exposed the cells to the virus in the lab. Adult stem cells can regenerate and turn into different types of specialized cells to help the body heal itself.
More than half the stem cells exposed to the virus turned into fat cells and accumulated fats, while only a small percentage of the non-exposed stem cells did the same, said researcher Dr. Magdalena Pasarica, who presented the results Monday at the American Chemical Society's annual meeting in Boston.
"It's the first time we see an effect in human cells," Pasarica said in a phone interview.
If a viral cause of obesity can be confirmed, a vaccine could be developed, maybe within five to 10 years, to prevent the virus from making some people fat, Dhurandhar said. However, it wouldn't help people already obese, he said.
Outside experts are intrigued but worry about people blaming all obesity on viruses, when this may be just one of many causes. It doesn't mean it's OK to overeat, blame a bug or wait for some kind of antivirus medicine, they said.
"The cause for obesity in everyone is the same," said Dr. Samuel Klein, director of the Center for Human Nutrition at the Washington University School of Medicine in St. Louis. "You eat more calories than you burn up; You can't get away from that basic law of physics."
But there are many causes that trigger overeating and extra storage of fat in the body, including the virus, Klein said. However, he said he considers the virus only a small factor, easily outweighed by genetics and even childhood eating habits.
Dhurandhar said some of his earlier research found that 30 percent of obese Americans had developed antibodies to the virus, showing they had been exposed to it at some point. But for non-obese people, only 11 percent had antibodies, he said.
That means for some people it is not their fault they are fat, Dhurandhar said.
But Klein said that's not completely right.
"We don't want obese people to feel that it's all their fault because it is not all their fault ... but clearly the buck finally lies with the person," Klein said.
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Tuesday, August 21, 2007
Health Care : Study finds virus contributes to obesity
Health Care : Too fat? Common virus may be to blame
A common virus caused human adult stem cells to turn into fat cells and could explain why some people become obese, U.S. researchers said on Monday. The research builds on prior studies of adenovirus-36 -- a common cause of respiratory and eye infections -- and it may lead to an obesity vaccine, they said.
"We're not talking about preventing all types of obesity, but if it is caused by this virus in humans, we want a vaccine to prevent this," said Nikhil Dhurandhar, an associate professor at Pennington Biomedical Research Center at Louisiana State University System. The virus adenovirus-36 or Ad-36, caused animals to pack on the pounds in lab experiments. "These animals accumulated a lot of fat," Dhurandhar said in a telephone interview.
Dhurandhar also has shown that obese people were three times more likely to have been infected with Ad-36 than thin people in a large study of humans.
Now, researchers in Dhurandhar's lab have shown that exposure to the virus caused adult human stem cells to turn into fat-storing cells.
Dr. Magdalena Pasarica, who led the study, obtained adult stem cells from fat tissue of people who had undergone liposuction. Stem cells are a type of master cell that exist in an immature form and give rise to more specialized cells.
Half of the stem cells were exposed to the virus Ad-36. After a week, most of the infected stem cells developed into fat cells, while the uninfected cells were unchanged.
Pasarica presented her findings at a meeting of the American Chemical Society in Boston.
"The virus appears to change their commitment to a fat storing cell," Dhurandhar said, adding that Ad-36 is just one of 10 pathogens linked to obesity and that more may be out there.
He acknowledged that some people might find it hard to believe that a virus could be responsible for obesity.
"Certainly overeating has something to do with gaining weight. No doubt about that. But that is not the whole truth," Dhurandhar said. "There are multiple causes of obesity. They range from simple overeating to genes to metabolism and perhaps viruses and infections."
Long term, he said he hoped to develop a vaccine and perhaps treatments for the virus. But first, he and colleagues need to better understand the role of Ad-36 in human obesity, he said.
Globally, around 400 million people are obese, including 20 million children under age 5, according to the World Health Organization.
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Health Care : Obesity predicts prostate cancer recurrence
Obese men have an increased risk of prostate cancer recurrence and death after they have completed radiation therapy, according to results of a study published in the medical journal BJU International. Obesity is known to predict prostate cancer progression in men who undergo radical prostatectomy, or complete surgical removal of the prostate gland, Dr. David Palma and colleagues from the British Columbia Cancer Agency, Vancouver, Canada, pointed out.
The researchers therefore examined whether obesity is associated with outcome for patients who undergo external beam radiation therapy for prostate cancer. Of 706 patients treated with radiation from 1994 through 2000, 195 were normal weight, 358 were overweight, and 153 were obese. There were no significant differences among the three groups in Gleason score (aggressiveness of the tumor); prostate-specific antigen (PSA) score (a prostate tumor marker) before treatment began; or cancer stage (how far the cancer has spread).
Blood levels of the male hormone testosterone were lower in obese men than in overweight and normal-weight men.
There were a total of 292 treatment failures detected by laboratory tests. The average times to relapse for normal-weight, overweight, and obese men were 93 months, 88 months, and 84 months, respectively.
The average times to prostate cancer death were 11.1 years for normal and overweight men, and 10.6 years for obese men, a statistically significant difference. The results of further analysis revealed a trend toward decreased overall survival by weight group.
"A number of explanations have been postulated to account for more aggressive prostate cancer in obese men," Palma and colleagues note. "Possible mechanisms include dietary factors, and alterations in hormonal levels, such as estrogens, androgens, leptin, and IGF-1, although definitive mechanisms have not been elucidated."
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Friday, August 17, 2007
Health Care : Obesity Heightens Kidney Disease Risks
Chronic kidney disease patients who are also obese are much more likely than normal-weight patients to have a condition called hyperparathyroidism, which raises their risk of heart problems and death, U.S. researchers say. Hyperparathyroidism involves elevated levels of parathyroid hormone (PTH). Normally, parathyroid hormone plays an important role in maintaining normal bone structure. Elevated levels of the hormone can lead to bone abnormalities and increased risk of cardiovascular disease and death. Decreased kidney function is the main cause of hyperparathyroidism in chronic kidney disease patients.
This study of 496 patients with moderate to severe chronic kidney disease who were not yet on dialysis showed a significant association between obesity and hyperparathyroidism. As body mass increased, so did PTH levels, the researchers said.
"We knew that in people with normal kidney function obesity leads to impairment in vitamin D metabolism and elevated PTH levels, but this phenomenon was never studied in patients with chronic kidney disease," lead author Dr. Csaba P. Kovesdy, of Salem VA Medical Center in Salem, Va., said in a prepared statement.
"Since both obesity and hyperparathyroidism are very complex problems in chronic kidney disease, establishing an association between the two is important because of potential prognostic and therapeutic implications," Kovesdy said.
The study is published in the September issue of the Clinical Journal of the American Society of Nephrology.
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Health Care : Obese people tend to pick overweight mates
A new UK study provides additional evidence that heavy people are more likely to choose other overweight individuals as mates. This phenomenon is known as "assortative mating" - when men and women tend to select partners according to nonrandom attributes such as height, religion, age and smoking habits.
Researchers have suggested that assortative mating by obesity could increase the already high prevalence of obesity by helping to pass on genes promoting excess weight to the next generation. To date, all studies investigating assortative mating for obesity have used body mass index or skin fold thickness to measure obesity, and many have not accounted for other potential contributing factors, Dr. John R. Speakman of the Rowett Research Institute in Aberdeen, Scotland and colleagues note.
Rowett and his team used a technique called dual-energy X-ray absorptiometry (DXA) to get a more precise picture of levels of body fat in their study participants, which included 42 couples. They used statistical techniques to measure and account for the effects of age, the postal code area where people had grown up, and the amount of time they had been in a relationship.
The researchers found that assortative mating for body composition had indeed occurred, with heavier people winding up with heavier mates. It's not clear why this happens, Speakman and his team note; leaner individuals may choose one another first, they suggest, leaving overweight people a more limited mate pool to pick from.
Aside from the underlying reason, they add, the fact that people are becoming overweight and obese at earlier ages than ever before could be making assortative mating for obesity even more common, because it is "allowing singles in their late teens and early twenties to more easily distinguish partners with obese and lean phenotypes."
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Health Care : Obesity may not bring on migraine
Obese middle-age and older women appear no more likely to report migraine than their non-obese counterparts, a new study suggests. Some previous studies have suggested that there is a relationship between obesity and migraine, while others have found no connection.
To further investigate, Dr. Peter Mattsson, of the department of Neuroscience and Neurology at University Hospital in Uppsala, Sweden enrolled 684 women, age 40 to 74 years, who were attending a mammography screening clinic between November 1997 and October 1998. Mattsson looked for an association between migraine and body mass index, a ratio of height to weight commonly used to determine if an individual is over- or underweight. His findings are reported in the medical journal Cephalalgia.
Overall, 19 percent of the women reported active migraine -- one or more migraine attacks during the previous year. Another 14 percent had inactive migraine -- previous migraine but not within the past year. Just over 19 percent of the study population was obese.
Mattsson found no association between active migraine or inactive migraine and obesity in this population of women. Thirty-two percent of the obese women had active migraine and 38 percent of the non-obese women had active migraine, a difference that was not statistically significant. Similar findings were obtained for inactive migraine.
He also found significant relationship between migraine characteristics -- frequency, intensity, and duration - and obesity in the study participants.
Mattsson notes that one recent population-based study, using interviews conducted by non-medical personnel and self-reports of physical characteristics, found an increased risk of migraine among obese and morbidly obese individuals compared with those of normal weight.
By contrast, Mattsson based his conclusions on data from interviews conducted by neurologists and actual body weight and height measurements. He found "no evidence in this study that obesity affects the prevalence of migraine among middle-aged and older women."
"If there are true associations between obesity and features of migraine such as frequency, these are likely to be small, and cannot be reliably studied in small or moderately sized community samples," Mattsson concludes.
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Tuesday, August 14, 2007
Placebo effect seen in kids during allergy testing
A "placebo effect" can cause a diverse array of symptoms in children when undergoing food allergy testing, according to the results of a study published in the current issue of Allergy. One of these effects is that some patients believe they have had an allergic reaction when they have actually received with the placebo. This reaction is sometimes referred to as a "nocebo" effect. The more conventional placebo reaction is an improvement of symptoms after receiving an inactive substance rather than the real medicine.
"To date, the occurrence and diagnostic significance of placebo events have not extensively been documented," Dr. B. J. Vlieg-Boerstra and colleagues from the University of Groningen, the Netherlands point out. To investigate, Vlieg-Boerstra's group conducted a double-blind, placebo-controlled food "challenge," in which a patient is exposed a substance that he is likely to be allergic to. A double-blind study is when the doctor and the patients do not know which is the placebo and which is the real medicine.
The researchers examined the occurrence and features of placebo reactions after 132 challenges in 105 children (average age 5.3 years) who were suspected of having an allergy to cow's milk, egg, peanut, hazelnut or soy. Challenges with a placebo or food were performed on different days with at least a 2-week interval in between.
A total of 17 (12.9 percent) false-positive reactions to the placebo occurred in 17 different children, meaning the children developed food allergy symptoms after being exposed to the placebo. Most of these symptoms (65 percent) were objective, such as rash, hives diarrhea and vomiting. The other symptoms were subjective -- reported by the child but couldn't really be verified.
The researchers conclude that doctors should be aware that some reactions to food allergy challenges may be false-positive, and that these sensitivity tests will need to be repeated.
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Estrogen loss contributes to obesity, high BP
The loss of estrogen that accompanies menopause contributes to the development of obesity and high blood pressure (hypertension), according to studies conducted in female rats. Estrogen is known to protect women against heart disease. When women reach menopause, their estrogen levels drop dramatically and they lose this protection and often put on weight Dr. Lourdes A. Fortepiani of the University of Texas Health Science Center at San Antonio, reported. The findings were reported by Dr. Fortepiani and her colleague Dr. Huimin Zhang at an American Physiological Society-sponsored meeting held in Austin.
The researchers showed that in older female rats, free of heart disease, estrogen deficiency appears to trigger the development of high blood pressure and obesity.
Rats that had their ovaries removed, thereby depleting their estrogen levels, had significantly higher blood pressure and gained twice as much weight as "control" rats with intact ovaries.
"The increase in blood pressure seems to be related to the increase in body weight," Fortepiani told Reuters Health.
Rats that had their ovaries removed also showed 70-percent higher levels of the fat hormone leptin and 35 percent higher blood sugar levels.
However, treating these "ovariectomized" rats with estrogen abolished these effects. "When you treat with estrogen, the animals don't gain that much weight and their blood pressure goes down," Fortepiani said.
Moreover, female rats without ovaries that receive estrogen replacement therapy do not experience any of these adverse hormonal and metabolic effects, she said.
While acknowledging the controversy surrounding hormone therapy, these findings may open up new therapeutic approaches for postmenopausal hypertension, Fortepiani added.
(source : news.yahoo.com)
Monday, August 13, 2007
Italian town to pay residents to shed flab
Overweight residents of an Italian town will be paid to lose weight, the mayor said on Monday. Men living in the northwestern Italian town of Varallo will receive 50 euros ($70) for losing 4 kg (9 pounds) in a month, Mayor Gianluca Buonanno said. Women will get the same amount for shedding 3 kg (7 pounds).
If they can keep the weight off for 5 months, they will get another 200 euros ($280), he told Reuters. "Lots of people are saying, 'I really need to lose some weight but it's really tough.' So I thought, why don't we go on a group diet?" said Buonanno, who said he was about 6 kg (13 pounds) overweight.
The town of 7,500 people started the campaign on Friday and some residents have already signed up, he said.
Around 35 percent of Italians are overweight or obese, according to European Union figures, with waistlines expanding as the country's healthy Mediterranean diet has given way to processed foods rich in fat, sugar and salt.
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Obesity-Linked Woes Boost Kids' Lifetime Heart Risk
Obese children diagnosed with health problems collectively known as the "metabolic syndrome" are at higher risk for developing heart disease as adults, new research reveals. Compared to healthier youngsters, school-age children with the condition face a 14.5 times greater risk of cardiovascular disease when they reached their 30s and 40s, the study found.
Components of the syndrome include high blood pressure, high body mass, high blood pressure and high triglycerides (blood fats). "I wasn't exactly shocked, but this is the first time we have shown that children who have this constellation of factors known as metabolic syndrome are at an increased risk for cardiovascular disease in their adult years," said study lead author John A. Morrison, a research professor of pediatrics who also works in the division of cardiology at Cincinnati Children's Hospital Medical Center in Ohio.
The findings are published in the August issue of Pediatrics.
According to the American Heart Association, more than 50 million Americans have the metabolic syndrome. The condition is typically diagnosed on the basis of having at least three of the following characteristics: abdominal obesity; high blood pressure; insulin resistance (in which the body can't process insulin or blood sugar properly); a high risk for arterial plaque build-up due to high levels of triglycerides, low HDL ("good") cholesterol and high LDL ("bad") cholesterol; and a high risk for clotting and inflammation as indicated by the elevated presence of certain blood proteins.
Researchers long ago established that, for adults, having the metabolic syndrome increases their risk for both heart disease and diabetes. Physicians now recommend that patients combating the condition embark on a weight-loss program geared toward developing healthier eating habits and increased physical activity.
To explore a possible link between pediatric metabolic syndrome and adult heart disease, Morrison and his team cross-referenced data for contributing syndrome characteristics collected from a pool of 771 children between 1973 and 1978, and then again between 2000 and 2004.
The participants were drawn from the Cincinnati region and were between the ages of 6 and 19 in the first study and 30 and 48 in the follow-up study. A little less than three-quarters of the pool were white and a little more than a quarter were black.
Patient blood samples were taken the time of study enrollment and then 25 years later. The researchers gauged blood pressure; body mass index (BMI); and cholesterol. Blood triglyceride and glucose levels were also assessed.
The participants also reported any history of heart attack or stroke, or procedures such as coronary bypass or angioplasty.
Four percent of the participants -- 31 boys and girls -- had metabolic syndrome as children, while more than 25 percent had the condition 25 years later, the researchers reported.
Among those with pediatric metabolic syndrome, almost 70 percent still had the condition as adults, and almost 20 percent had gone on to develop cardiac disease in the intervening years.
In contrast, only 1.5 percent of the children who did not have the syndrome as kids went on to experience heart trouble as adults.
Furthermore, any rise or fall in BMI over the 25 years was linked to a concurrent rise or fall in risk for developing the metabolic syndrome. In that time frame, every BMI bump or drop of 10 points translated into a 24 percent risk increase or decrease for the syndrome, the team reported.
Morrison and his colleagues said their findings should help doctors and parents identify young patients who are at an increased risk for serious adult illness. They could also point the way toward ways to reduce that risk.
"So, there's some good news here," said Morrison. "Pediatric weight is not destiny. If you're obese as a child, you can do something to lose the pounds. And you must do something to lose the pounds, if you want to reduce risk."
Dr. Brenda Kohn, an associate professor of pediatrics at the New York University School of Medicine, added that proactive parental and physician intervention is critical to help children avoid behaviors that keep the syndrome going.
"The treatment has to be started in childhood, in adolescence," she advised. "Eating patterns, activity patterns, all start in infancy. Good habits have to start early."
"So, it's very, very important that a child is raised in an environment where physical exercise is encouraged on a routine basis and eating patterns are geared to healthy eating decisions," added Kohn, who is also a medical advisory board member with the Juvenile Diabetes Foundation. "Children should be monitored at least once yearly by a physician in order to ensure that all these goals are being met," she said.
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Obese elementary schoolchildren miss a couple more school days on average than their normal-weight classmates, according to a study that says being fat is a better predictor for absenteeism than any other factor. Researchers said their results suggest that childhood obesity, in addition to serious medical issues, can lead to a plethora of additional problems down the road.
"It's clear in all the literature that the more days of school you miss, it really sets you up for such negative outcomes: drugs and AIDS and (teen) pregnancy," said Andrew B. Geier, a doctoral candidate at the University of Pennsylvania and lead author of the study released Friday. He said the findings should serve as a clarion call to school officials.
"At this early age to show that already they're missing school, and missing school is such a major setup for big-time problems, that's something school policy people have to know," Geier said.
The researchers from Penn and Temple University looked at 1,069 fourth- to sixth-graders for one academic year in nine Philadelphia schools, where teachers took attendance each morning. Based on body mass index, a standard measure of height and weight, each child was classified as underweight, normal weight, overweight or obese.
Of 180 school days, researchers found that on average the normal weight students missed 10.1 days, overweight kids missed 10.9 days and obese children missed 12.2 days. For reasons that aren't clear, underweight children had the fewest absences — 7.5 on average.
In decades of research about student performance, race, socioeconomic status, age and gender have been tagged as the top predictors for absenteeism. The new study, in the latest issue of the journal Obesity, concludes that weight tops them all, Geier said.
The study didn't explore why the children missed school. Researchers theorize it's got less to do with medical issues — many children at this young age haven't yet developed major obesity-linked maladies — and more to do with the stigma of being fat.
"They're missing school because they don't want to be bullied and called names," Geier said.
Researchers tried to make the test group as homogeneous as possible by picking schools that were among the city's poorest, with the assumption that education and income levels would be fairly even.
Nationally, obesity rates have nearly quintupled among 6- to 11-year-olds and tripled among teens and children ages 2 to 5 since the 1970s, according to the Centers for Disease Control and Prevention. Obesity can lead to diabetes, high blood pressure and cholesterol, sleep apnea and orthopedic problems.
The study adds to growing research into non-medical complications of being fat, including data suggesting that obese adults miss more workdays and go to college less frequently than people of normal weight, Geier said.
"This is exactly the kind of study that will get the attention of policy makers," said Jim Bogden, healthy eating project coordinator for the National Association of State Boards of Education. "The correlation with absenteeism is very powerful."
He likened the results to studies linking academic achievement to participation in school breakfast programs — research that prompted lots of schools to start offering such programs. In this case, changes could include anything from improving nutrition education and cafeteria offerings to getting parents to serve healthy meals at home.
"Those of us working in school health do all we can to publicize this information, and it seems to be starting to sink in," Bogden said.
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Friday, August 10, 2007
Health Care "Fat" hormone sheds new light on obesity
The hormone that tells us we are full also regulates our desire for certain foods, researchers said on Thursday, in a finding that sheds light on why people gain weight and could lead to new treatments for obesity. The study showed that patients with a rare genetic disorder who lacked the hormone called leptin ate less after receiving injections of the hormone, said I.S. Farooqi, a researcher at Cambridge University who led the study.
Previous research has shown the hormone does not help people with normal leptin levels lose weight, but scientists still do not completely understand how it works, Farooqi said. "By studying patients who have no leptin and then treating them with leptin, we can tell what it is doing," Farooqi said in a telephone interview. "It gives a clear look at how leptin operates in the brain."
In the study, published in the journal Science, researchers searched for "circuits" in the brain that signal when a person is hungry or full and found that they were linked to areas involved in determining the enjoyment of food. To see how the hormone worked, the researchers showed the patients pictures of different types of food, ranging from tasty fare like chocolate cake and pizza to blander choices such as cauliflower and broccoli.
The patients with the genetic disorder -- of which there are about a dozen known cases in the world -- liked all types of food, ate excessively and were obese, the researchers said.
Using magnetic resonance imaging technology, the researchers tracked the patients' brain activity as they responded to the pictures and pinpointed several key areas that play an important role when it comes to a desire for food.
After the patients received leptin injections, the areas that had previously shown activity all the time at the sight of food were only active if the people had not eaten the night before, which was a normal response, Farooqi said.
It showed desire for food is driven by biology -- not greed -- which causes overeating and obesity, Farooqi said.
Knowing how leptin, which is produced by fat cells, triggers different parts of the brain could lead to new drugs that target obesity and help dangerously overweight people take pounds off.
"If you find those molecules that leptin triggers then you can manipulate or target them with drugs to treat obesity," Farooqi said. "The first step is to work out what leptin does and how it does it."
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Thursday, August 9, 2007
Panel worried about baby bottle chemical
A chemical used in plastic baby bottles and other products may affect unborn babies and young children and more study on its safety is needed, a U.S. panel of experts said on Wednesday. The National Toxicology Program Center for the Evaluation of Risks to Human Reproduction convened an expert panel on the effects of bisphenol A, used in clear plastic polycarbonate bottles. Its report will be available later this year, the NTP said.
It said the panel of experts "expressed negligible concern that exposure to Bisphenol A in utero produces birth defects and malformations." But for pregnant women and fetuses, the committee expressed some concern that exposure to Bisphenol A in utero causes neural and behavioral effects.The NTP, part of the National Institute of Environmental Health Sciences, said people can be exposed to the chemical by direct contact or via food or drink that has been in contact with a material containing bisphenol A.
Environmental groups have for years been complaining about the safety of plastic toys, baby bottles and other products containing bisphenol A and pother chemicals known as phthalates.
"(The Center) selected this chemical for evaluation because of (1) high production volume, (2) widespread human exposure, (3) evidence of reproductive toxicity in laboratory animal studies, and (4) public concern," the NTP said in a statement.
Polycarbonate plastics are used in food and drink packaging and resins are used to coat metal products such as food cans, bottle tops, and water supply pipes.
The Juvenile Products Manufacturers Association, which represents the leading manufacturers of baby bottles in the United States, said the panel's brief statement suggested the bottles are safe.
"The Panel's conclusions today reaffirm the safety of plastic baby bottles," said JPMA President Robert Waller.
"These findings validate the Food and Drug Administration's conclusions and the conclusions of governments and independent scientists worldwide that polycarbonate plastic baby bottles are safe."
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Low-Cal Sweets Might Still Make Kids Obese
Diet foods and drinks meant to help children control their weight may actually spur overeating and obesity, Canadian researchers say. The study found that animals learn to associate the taste of food with the amount of caloric energy it provides. The researchers speculate that children who eat low-calorie versions of foods that normally have a high calorie content may develop distorted connections between taste and calorie content, resulting in overeating as the children grow up.
"The use of diet food and drinks from an early age into adulthood may induce overeating and gradual weight gain through the taste conditioning process that we have described," lead author and sociologist Dr. David Pierce, of the University of Alberta, said in a prepared statement. In a series of experiments published Aug. 8 in the journal Obesity, the researchers found that young rats started to overeat when they received low-calorie food and drink. Adolescent rats did not overeat when given low-calorie items.
This may be because, unlike the younger rats, the adolescent rats didn't rely on taste-related cues to assess the caloric energy content of their food, the researchers said.
"Based on what we've learned, it is better for children to eat healthy, well-balanced diets with sufficient calories for their daily activities rather than low-calorie snacks or meals," Pierce said.
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Wednesday, August 8, 2007
Maternal Obesity Heightens Risk of Birth Defects
Women who were obese before they became pregnant had a higher risk of having babies with certain birth defects, including missing limbs, malformed hearts and underdeveloped spinal cords, a new study found. But the researchers cautioned that overweight women planning to get pregnant should try to lose weight sensibly and carefully.
"We would advise women who are obese to try to maintain a healthy weight, engage in moderate exercise and follow a healthy daily diet," said study lead author Kim Waller, associate professor of epidemiology at the University of Texas at Houston's School of Public Health. "Multivitamins both before and after a woman becomes pregnant are very important." In particular, women are advised to take 400 micrograms of folic acid daily both before pregnancy and during pregnancy. A multivitamin will usually satisfy this recommendation.
And women should not try fad diets.
"We don't want women who are thinking of becoming pregnant or who are pregnant to rush out and go on a crash diet," Waller cautioned. "If you become pregnant, then, sure, maybe try to lose some weight, but do so very, very carefully and maintain a healthy diet while you're doing so."
"You have to be of a healthy weight not only for yourself but also for a healthy pregnancy," added Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City. "You want to try to get down to a healthy weight before you even get pregnant in the first place. Pregnancy is not the time to do a crash diet to try to lose weight."
In 2003 and 2004, 51 percent of U.S. women aged 20 to 39 were overweight or obese, putting them at increased risk for chronic diseases, infertility, irregular menstruation and pregnancy complications, according to background information in the study.
Previous research had shown a strong association between pre-pregnancy body mass index (BMI, a ratio of weight to height) and the risk for certain birth defects, particularly anencephaly -- a defect in the closure of the neural tube, which forms the brain and spinal cord of the embryo -- and spina bifida. The link between overweight and obesity and other birth defects has been less clear.
According to the U.S. Agency for Healthcare Research and Quality, as many as one in 33 babies born in the United States has a birth defect. For the new study, the largest of its kind, Waller and her colleagues interviewed 10,249 women in eight states whose babies had been born with birth defects between 1997 and 2002. Information on the women came from the National Birth Defects Prevention Study.
These women were then compared to 4,065 women who had given birth to babies without birth defects during the same time period. Sixteen birth defects were studied. Of those, mothers of babies with the following seven birth defects were more likely to have been obese than mothers of infants without birth defects:
- Spina bifida, or the incomplete development of the brain, spinal cord and/or meninges (the protective covering around the brain and spinal cord). This is the most common neural tube defect in the United States and affects up to 2,000 of the more than 4 million babies born annually, according to the National Institutes of Health.
- Heart defects.
- Anorectal atresia, or malformation of the anal opening.
- Hypospadias, or an abnormally placed urethral opening in males -- on the underside instead of the end of the penis.
- Limb reduction defects, such as small or missing toes, fingers, arms or legs.
- Diaphragmatic hernia, an opening in the diaphragm that allows abdominal organs to move into the chest cavity. This may also cause lungs to be underdeveloped.
- Omphalocele, when the intestines or other abdominal organs protrude through the navel.
The findings are published in the August issue of Archives of Pediatrics & Adolescent Medicine.
It's not clear why the association between pre-pregnancy obesity and birth defects exists.
"We know that obese women have a higher risk of certain defects, but we don't know if obesity is the direct cause," Waller said. "There could be other explanations, such as different types of diet, different ways of dieting when they're dieting. We were not able to exclude women with diabetes, and that is a very strong risk factor for birth defects, so we think there may be undiagnosed cases of diabetes remaining with the study."
Future research will look at dieting techniques and the risk of birth defects, as well as any links between over-the-counter diuretics and appetite suppressants and birth defects.
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Tuesday, August 7, 2007
Mom's obesity linked with birth defects
Women who are obese before pregnancy face a higher risk of having babies with a variety of birth defects than women with a healthy weight, a new study suggests. The results involving nearly 15,000 women from eight states found abnormalities of the spine, heart, arms, legs and abdomen, building on previous research that showed heart and spine defects. The greatest risk was for spina bifida.
"Obese women should not be overly alarmed by these findings because their absolute risk of having a child with a birth defect is low, and the cause of the majority of birth defects is unknown," said University of Texas researcher Kim Waller, the study's lead author. Still, the results underline yet another reason for women to maintain a healthy weight, Waller said.
The findings suggest that about 4 percent of women who are obese before pregnancy will have babies with major birth defects, versus 3 percent for healthy-weight women, Waller said.
Obese women faced double the risk of having babies with spina bifida than women of healthy weight. With spina bifida, the most common disabling birth defect in the United States, the spinal column fails to close properly. That often leads to leg paralysis, learning difficulties and other serious problems.
Very heavy women also were 60 percent more likely to have babies born with a rare defect in which abdominal organs protrude through the belly button; 40 percent more likely to have heart defects; 36 percent more likely to have shortened arms or legs; and at least 20 percent more likely to have any of several gastrointestinal deformities.
The study was released Monday in the August edition of Archives of Pediatrics & Adolescent Medicine. It was funded by the federal Centers for Disease Control and Prevention.
"This is probably an under-recognized finding which I suspect will be corroborated by other research in the future and something we will need to talk to our patients about," said Dr. Alan Peaceman, a high-risk pregnancy specialist and professor at Northwestern University.
Dr. Michael Katz, acting medical director for the March of Dimes, said, "It's important because if it is true," it suggests that rising obesity rates might be triggering increases in birth defects.
The research is part of the National Birth Defects Prevention Study, involving women who were pregnant between October 1997 and December 2002.
Participants included 10,249 women whose babies were born with at least one birth defect. They were compared with 4,065 women with healthy babies.
Women were asked what their height and weight had been just before they got pregnant. Based on those responses, the researchers calculated that 2,312 women were obese pre-pregnancy.
Reasons for the potential link between obesity and birth defects are unclear, Waller said. It's possible that some women had undiagnosed diabetes, which also is linked to birth defects, she said.
While the study didn't examine weight during pregnancy, it's also possible that some women tried potentially dangerous weight-loss techniques right before conception or during early pregnancy, when most birth defects occur, the researcher said.
She urged obese pregnant women, however, not to try diet pills, fasting or other aggressive methods which also might contribute to risks for birth defects.
source : news.yahoo.com
Obesity before pregnancy ups risk of birth defects
There's an increased risk of birth defects among babies born to women who are obese before becoming pregnant, according to a new study. To look into this issue, Dr. D. Kim Waller and colleagues used information from the ongoing National Birth Defects Prevention Study, a multi-site, population-based study of more than 30 different categories of structural birth defects.
Waller, at the University of Texas in Houston, and associates pulled data for births between 1997 and 2002 on over 10,000 babies born with birth defects and compared them with some 4000 normal babies. The team found that maternal obesity more than doubled the likelihood that the baby would have spina bifida. Other increased risks linked to the mother's pre-pregnancy obesity were defects involving the heart, anus, penis, limbs, diaphragm and navel, the researchers report in the Archives of Pediatrics and Adolescent Medicine.
For mothers who were overweight but not classified as obese, there was also a significant, but smaller, association with some of these defects.
Among underweight women, the only defect linked to their weight was a slightly increased risk of cleft lip.
Waller and colleagues conclude: "Our study supports previous evidence as well as provides new evidence for the associations between maternal obesity and particular categories of birth defects."
source : news.yahoo.com
Monday, August 6, 2007
Fatter Australians cause hazard for mortuaries
More than two-thirds of Australians living outside major cities are overweight or obese, and extremely obese corpses are creating a safety hazard at mortuaries, according to two studies released on Sunday. Nearly three quarters of men and 64 percent of women were overweight in a study of people in rural areas. Just 30 percent of those studied recorded a healthy weight, said research published in the Medical Journal of Australia.
"Urgent action is required at the highest level to change unhealthy lifestyle habits by improving diet, increasing physical activity and making our environments supportive of these objectives," wrote the lead researcher, Professor Edward Janus. The figures were much higher than for the general population, where statistics show about 3.2 million of Australia's 21 million people are obese.
Meanwhile, pathologists are calling for new "heavy-duty" autopsy facilities to cope with obese corpses that are difficult to move and dangerously heavy for standard-size trolleys and lifting hoists.
The bodies presented "major logistical problems" and "significant occupational health and safety issues," according to a separate study, which found the number of obese and morbidly obese bodies had doubled in the past 20 years.
Specially designed mortuaries would soon be required if the nation failed to curb its fat epidemic, providing "larger storage and dissection rooms, and more robust equipment," said Professor Roger Byard, a pathologist at the University of Adelaide.
"Failure to provide these might compromise the post-mortem evaluation of markedly obese individuals, in addition to potentially jeopardizing the health of mortuary staff."
In the past year, there have also been requests for larger crematorium furnaces, bigger grave plots as well as super-sized ambulances, wheelchairs and hospital beds.
source : news.yahoo.com
Saturday, August 4, 2007
Fat-burning defect in liver may cause obesity
Rats with a genetic predisposition to burn fat more slowly tend to put on weight more readily than rodents bred to resist becoming obese, a new study shows. The findings could help explain why some people get fat more readily than others, Dr. Mark I. Friedman of the Monell Chemical Senses Center in Philadelphia, one of the study's authors, told Reuters Health.
Just like the animals in the study, he explained, it may be harder for obesity-prone people to use energy from the fats they eat -- as well as to burn fat from their own bodies -- forcing them to overeat to get enough energy. Essentially, Friedman said, "they overeat because they're getting fat." Previous studies in people have found that individuals who burn fat slowly are more likely to subsequently gain weight, Friedman and his colleague Dr. Hong Ji note in the current issue of the journal Metabolism: Clinical and Experimental. To determine if impaired fat oxidation might be involved in the development of obesity, the researchers fed a low-fat diet to rats bred to either be susceptible or resistant to obesity, and then switched them to a high-fat diet.
No weight difference developed between the two groups of rats while they were eating a low-fat diet, the researchers found. However, the obesity-prone rats showed a 35-percent lower rate of fatty acid oxidation. And after the animals were switched to a higher fat diet, the obesity-prone rats gained 36 percent more weight than the obesity-resistant rats, even though they consumed just 14 percent more calories.
The obesity-prone rats also showed reduced expression of genes involved in transporting fatty acids to the liver cells and burning them to make energy.
The findings imply that impairment of fatty acid oxidation may contribute to obesity in humans, Ji and Friedman conclude.
While fat metabolism may be at fault, Friedman added, people who want to control their weight should be paying attention to carbs, too. "As far as diet recommendations go, I personally would not pin it all on the fat. I would say that it really depends on a mix of fat and carbohydrates."
Friedman and his colleagues are now looking into the enzymes involved in fatty acid oxidation and how their function might be altered in obesity-prone rats, which could provide an approach to treating or preventing obesity in humans.
source : news.yahoo.com
Thursday, August 2, 2007
Health Care : Dietary carbs linked to vision loss
The carbohydrates present in a diet can influence the risk of age-related macular degeneration (AMD), the most common cause of vision loss in older adults, according to a report in the American Journal of Clinical Nutrition. "AMD appears to share several carbohydrate-related mechanisms and risk factors with diabetes-related diseases, including (eye) and cardiovascular disease," write Dr. Allen Taylor, of Tufts University, Boston, and colleagues. "However, to date, only one small study has addressed this issue."
To investigate further, the researchers conducted a study of 4,099 participants, aged 55 to 80 years, in the Age-Related Eye Disease Study. The team classified a total of 8,125 eyes into one of five AMD groups based on the severity of the disease and other factors.
Regular consumption of a diet with a high-glycemic index - a diet containing carbs that quickly raise blood sugar levels -- significantly increased the risk of AMD relative to regular consumption of a diet with a low-glycemic index. The researchers calculate that 20 percent of AMD cases could have been prevented if subjects had consumed diets with a low-glycemic index.
source : news.yahoo.com
