Monday, May 31, 2010
Research sheds new light on the role bacteria in the digestive tract may play in obesity. The studies, which were presented at the 110th General Meeting of the American Society for Microbiology, paint a picture that may be more complex than originally thought.
"Work currently underway suggests that an interaction between genetic factors and the composition of the bacteria that inhabit the human gut may predispose certain individuals towards obesity. These results potentially provide insight into the mechanisms by which genetics may predispose some people to obesity. They could also help pave the way towards a future in which genetic screening in conjunction with individually tailored treatments could help people at risk for obesity to maintain a healthy weight," says Margaret Zupancic, of the Institute for Genome Sciences at the University of Maryland School of Medicine, who presented one of the studies.
Zupancic and her colleagues analyzed the gut bacterial communities of lean and obese individuals belonging to the Old Order Amish of Lancaster County, Pennsylvania -- a population relatively homogenous in regard to both genetics and lifestyle. Initially they found no correlation between the composition of the gut bacteria and obesity, but when they factored in the genetic makeup of the participants, certain patterns began to emerge.
One pattern was a statistically significant correlation between whether the participant carried a given variant of the FTO gene (a gene associated with obesity) and the presence of certain bacterial groups in the digestive tract.
The researchers also found that in people with certain genetic variations in taste receptor genes, a low level of bacterial diversity in the gut correlated with a higher likelihood of obesity, while a high level of diversity correlated with a lower likelihood of obesity.
"While this work is still at a relatively early stage, results such as these could lead to applications such as probiotic or antibiotic-based treatments for obesity that could be individualized based on a person's unique genetic and gut microbial makeup," says Zupancic.
Another study from the Fred Hutchinson Cancer Research Center analyzed the gut microbes of women between 40 and 45 years of age. The researchers found a positive correlation between the population of one specific type of bacteria, Bacteroidetes, and body fat percentage in the participants.
Not all research presented at the meeting found differences in bacterial populations in the gut and obesity. One study, focusing specifically on children and childhood obesity, failed to identify any significant differences in the gut microbial communities of obese and normal-weight children.
The researchers subsequently analyzed the ability of the microbes to extract and convert dietary energy. They found higher levels of short-chain fatty acids in the feces of obese children.
"This suggests that although obese and normal-weight children have similar gut microbial communities, the gut microbes in obese children are more efficient at converting dietary substrates into energy," says Amanda Payne of the Institute of Food Health and Nutrition ETH, Zurich, Switzerland.
Short-chain fatty acids are converted into triglycerides and glucose by the liver, a process estimated to provide an additional 10% of dietary energy. The increased production of short-chain fatty acids by gut microbes in obese children could potentially supply more dietary energy, resulting in weight gain.
"While the importance of a balanced diet and regular exercise should not be discounted, our results may help contribute to the development of novel approaches in treating childhood obesity by modulating the composition and activity of the gut microbiota in order to reduce energy extraction from undigested food," says Payne.
Sourse : ScienceDaily
"Work currently underway suggests that an interaction between genetic factors and the composition of the bacteria that inhabit the human gut may predispose certain individuals towards obesity. These results potentially provide insight into the mechanisms by which genetics may predispose some people to obesity. They could also help pave the way towards a future in which genetic screening in conjunction with individually tailored treatments could help people at risk for obesity to maintain a healthy weight," says Margaret Zupancic, of the Institute for Genome Sciences at the University of Maryland School of Medicine, who presented one of the studies.
Zupancic and her colleagues analyzed the gut bacterial communities of lean and obese individuals belonging to the Old Order Amish of Lancaster County, Pennsylvania -- a population relatively homogenous in regard to both genetics and lifestyle. Initially they found no correlation between the composition of the gut bacteria and obesity, but when they factored in the genetic makeup of the participants, certain patterns began to emerge.
One pattern was a statistically significant correlation between whether the participant carried a given variant of the FTO gene (a gene associated with obesity) and the presence of certain bacterial groups in the digestive tract.
The researchers also found that in people with certain genetic variations in taste receptor genes, a low level of bacterial diversity in the gut correlated with a higher likelihood of obesity, while a high level of diversity correlated with a lower likelihood of obesity.
"While this work is still at a relatively early stage, results such as these could lead to applications such as probiotic or antibiotic-based treatments for obesity that could be individualized based on a person's unique genetic and gut microbial makeup," says Zupancic.
Another study from the Fred Hutchinson Cancer Research Center analyzed the gut microbes of women between 40 and 45 years of age. The researchers found a positive correlation between the population of one specific type of bacteria, Bacteroidetes, and body fat percentage in the participants.
Not all research presented at the meeting found differences in bacterial populations in the gut and obesity. One study, focusing specifically on children and childhood obesity, failed to identify any significant differences in the gut microbial communities of obese and normal-weight children.
The researchers subsequently analyzed the ability of the microbes to extract and convert dietary energy. They found higher levels of short-chain fatty acids in the feces of obese children.
"This suggests that although obese and normal-weight children have similar gut microbial communities, the gut microbes in obese children are more efficient at converting dietary substrates into energy," says Amanda Payne of the Institute of Food Health and Nutrition ETH, Zurich, Switzerland.
Short-chain fatty acids are converted into triglycerides and glucose by the liver, a process estimated to provide an additional 10% of dietary energy. The increased production of short-chain fatty acids by gut microbes in obese children could potentially supply more dietary energy, resulting in weight gain.
"While the importance of a balanced diet and regular exercise should not be discounted, our results may help contribute to the development of novel approaches in treating childhood obesity by modulating the composition and activity of the gut microbiota in order to reduce energy extraction from undigested food," says Payne.
Sourse : ScienceDaily
Thursday, May 20, 2010
It's a paradox that has flummoxed women for generations – their apparent ability to store fat more efficiently than men, despite eating proportionally fewer calories.
While it has long been suspected that female sex hormones are responsible, a University of New South Wales (UNSW) research review has for the first time drawn a link between one hormone – oestrogen – and its impact on fat storage for childbearing.
On average, women have 6 to 11 percent more body fat than men. Studies show oestrogen reduces a woman's ability to burn energy after eating, resulting in more fat being stored around the body. The likely reason is to prime women for childbearing, the review suggests.
"Female puberty and early pregnancy – times of increased oestrogen – could be seen as states of efficient fat storage in preparation for fertility, foetal development and lactation," the study's author Associate Professor Anthony O'Sullivan, from UNSW's St George Clinical School, said.
The findings, which appear in Obesity Reviews, may have implications for dietary advice given to women during pregnancy and the design of exercise regimes.
"From an energy balance point of view there is no explanation why women should be fatter than men, particularly since men consume more calories proportionately," Associate Professor O'Sullivan said. "In fact, women burn off more fat than men during exercise, but they don't lose body fat with exercise as much suggesting women are more efficient fat storers at other times. The question is why does this paradox exist?"
An obvious answer is that fat storage by women gives an evolutionary benefit, he said. However, additional research was needed to provide more insights into the role of oestrogen in the regulation of body fat.
Associate Professor O'Sullivan stressed that while oestrogen's effects on postprandial fatty acid oxidation provide a mechanism for fat accumulation, the findings do not explain why some women are obese. Factors contributing to obesity are complex and include both genetic and environmental factors, he said.
Story Source: ScienceDaily
While it has long been suspected that female sex hormones are responsible, a University of New South Wales (UNSW) research review has for the first time drawn a link between one hormone – oestrogen – and its impact on fat storage for childbearing.
On average, women have 6 to 11 percent more body fat than men. Studies show oestrogen reduces a woman's ability to burn energy after eating, resulting in more fat being stored around the body. The likely reason is to prime women for childbearing, the review suggests.
"Female puberty and early pregnancy – times of increased oestrogen – could be seen as states of efficient fat storage in preparation for fertility, foetal development and lactation," the study's author Associate Professor Anthony O'Sullivan, from UNSW's St George Clinical School, said.
The findings, which appear in Obesity Reviews, may have implications for dietary advice given to women during pregnancy and the design of exercise regimes.
"From an energy balance point of view there is no explanation why women should be fatter than men, particularly since men consume more calories proportionately," Associate Professor O'Sullivan said. "In fact, women burn off more fat than men during exercise, but they don't lose body fat with exercise as much suggesting women are more efficient fat storers at other times. The question is why does this paradox exist?"
An obvious answer is that fat storage by women gives an evolutionary benefit, he said. However, additional research was needed to provide more insights into the role of oestrogen in the regulation of body fat.
Associate Professor O'Sullivan stressed that while oestrogen's effects on postprandial fatty acid oxidation provide a mechanism for fat accumulation, the findings do not explain why some women are obese. Factors contributing to obesity are complex and include both genetic and environmental factors, he said.
Story Source: ScienceDaily
Tuesday, May 18, 2010
Losing weight is a simple mathematical formula: You need to burn more calories than you eat. Experts generally recommend creating a deficit of 500 calories per day through a combination of eating fewer calories and increasing physical activity. Over the course of a week, this should yield a loss of about 1-2 pounds of fat.
If you want to lose weight faster, you'll need to eat less and exercise more. Bottom line: 1,050 to 1,200 calories and one hour of exercise a day (but be sure not to dip below this calorie level for safety's sake). On this type of plan, you can expect to lose 3-5 pounds the first week, or more if you weigh over 250 pounds.
"Dieters who follow the plan can lose 2 pounds from diet and 1 pound from exercise each week, and even more if they have more to lose, because the more fat you have to lose, the faster it comes off," says Dansinger.
You may lose even more weight initially if you limit salt and starches.
"When you reduce sodium and cut starches, you reduce fluids and fluid retention, which can result in up to 5 pounds of fluid loss when you get started," explains Dansinger.
Diets for Fast Weight Loss
When it comes to weight loss, calories count the most, says Dansinger. He recommends cutting back to a daily level of 7 calories per pound of your current body weight (which for a 200-pound person, for example, would be 1,400 calories), but no less than 1,050 calories/day (the lowest level that can be done safely at home). Dietitians more typically recommend 1,200 calories as a daily minimum.
Dansinger advocates a diet that minimizes starches, (even healthy whole grains should be controlled), added sugars, and animal fat from meat and dairy foods. For rapid weight loss, dieters should eat mainly fruits, veggies, egg whites, soy products, skinless poultry breasts, fish, shellfish, nonfat dairy foods, and 95% lean meat.
He notes that there are other ways to control calories, such as minimizing total fat, but believes that tends to be more challenging than his suggested weight loss plan.
Other experts interviewed by WebMD recommended tactics including drinking lots of water, eating plenty of protein, and keeping a food journal.
"Eat enough protein and distribute it evenly through your meals to minimize muscle loss and maximize fat loss," says Tallmadge, author of Diet Simple, who also advises clients to swap out carbs in favor of veggies.
American Dietetic Association spokesperson Dawn Jackson Blatner, RD, recommends:
Weighing yourself daily and tracking your food intake can also help you keep focused, experts say.
"Even if you write it down on a napkin and end up throwing it away, the act of writing it down is about being accountable to yourself and is a very effective tool for weight loss," says Bonnie Taub Dix, MA, RD, a food and nutrition blogger for USA Today.
Although it won't actually help you lose weight, Blatner, author of The Flexitarian Diet, says that eating fennel seeds, ginger, parsley, peppermint, pineapple, and yogurt with honey one to three days before the big event can help you de-bloat and keep your tummy feeling flatter.
Source : WebMD
If you want to lose weight faster, you'll need to eat less and exercise more. Bottom line: 1,050 to 1,200 calories and one hour of exercise a day (but be sure not to dip below this calorie level for safety's sake). On this type of plan, you can expect to lose 3-5 pounds the first week, or more if you weigh over 250 pounds.
"Dieters who follow the plan can lose 2 pounds from diet and 1 pound from exercise each week, and even more if they have more to lose, because the more fat you have to lose, the faster it comes off," says Dansinger.
You may lose even more weight initially if you limit salt and starches.
"When you reduce sodium and cut starches, you reduce fluids and fluid retention, which can result in up to 5 pounds of fluid loss when you get started," explains Dansinger.
Diets for Fast Weight Loss
When it comes to weight loss, calories count the most, says Dansinger. He recommends cutting back to a daily level of 7 calories per pound of your current body weight (which for a 200-pound person, for example, would be 1,400 calories), but no less than 1,050 calories/day (the lowest level that can be done safely at home). Dietitians more typically recommend 1,200 calories as a daily minimum.
Dansinger advocates a diet that minimizes starches, (even healthy whole grains should be controlled), added sugars, and animal fat from meat and dairy foods. For rapid weight loss, dieters should eat mainly fruits, veggies, egg whites, soy products, skinless poultry breasts, fish, shellfish, nonfat dairy foods, and 95% lean meat.
He notes that there are other ways to control calories, such as minimizing total fat, but believes that tends to be more challenging than his suggested weight loss plan.
Other experts interviewed by WebMD recommended tactics including drinking lots of water, eating plenty of protein, and keeping a food journal.
"Eat enough protein and distribute it evenly through your meals to minimize muscle loss and maximize fat loss," says Tallmadge, author of Diet Simple, who also advises clients to swap out carbs in favor of veggies.
American Dietetic Association spokesperson Dawn Jackson Blatner, RD, recommends:
* Eat plenty of low-calorie vegetables to help you feel full.
* Drink plenty of water so you don't confuse hunger with thirst.
* Clear the house of tempting foods.
* Stay busy to prevent eating out of boredom.
* Eat only from a plate, while seated at a table.
* Always eat three meals and one snack daily -- no skipping meals.
Weighing yourself daily and tracking your food intake can also help you keep focused, experts say.
"Even if you write it down on a napkin and end up throwing it away, the act of writing it down is about being accountable to yourself and is a very effective tool for weight loss," says Bonnie Taub Dix, MA, RD, a food and nutrition blogger for USA Today.
Although it won't actually help you lose weight, Blatner, author of The Flexitarian Diet, says that eating fennel seeds, ginger, parsley, peppermint, pineapple, and yogurt with honey one to three days before the big event can help you de-bloat and keep your tummy feeling flatter.
Source : WebMD
Friday, May 14, 2010
ScienceDaily (May 13, 2010) — Having a balanced diet is a vital concern to all living organisms, not only humans. Animals choose between different food sources according to their nutritional needs. In a study just published in the journal Current Biology, Carlos Ribeiro, group leader in the Champalimaud Neuroscience Programme at the Instituto Gulbenkian de Ciência (Portugal), and Barry Dickson, at the Institute of Molecular Pathology (Austria), provide the first indication of the genes and brain circuits involved in this decision process, in the fruit fly Drosophila melanogaster, opening the way for understanding feeding decisions in other organisms, from the malaria-carrying mosquito to humans.
Carlos Ribeiro followed Drosophila foraging habits for several weeks and found that fruit flies choose between different food sources according to their nutritional requirements, gender and mating status. Carlos describes their findings, 'Normally when kept on "complete food" (with sugar and yeast) and given the choice, flies do not eat food with proteins (yeast-enriched). However, after a few days on a protein-poor diet, flies preferred a yeast-rich diet. Female flies switch diets more quickly than males, and mated females quicker than virgin females.
The researchers used a simple and clever assay to follow the type of food flies preferred: they added a blue dye to the yeast-enriched food and a red dye to the 'sugar rich food', and then looked at the bellies of the flies, to know which food they had eaten.
Carlos says, 'This assay, and the powerful genetics of the fruit fly, allowed us to take the next step, and describe the molecules and neurons which make mated females react faster than virgin females, as well as the molecules which act in the brain of flies to detect a lack proteins and make the flies change their decisions -- the sensor, so to speak'.
The sensor turns out to be the same that might regulate feeding habits of both female mosquitoes and vertebrates. In humans, regulation of protein and carbohydrate uptake could be an important component of eating disorders -- a major health problem in western societies. Amongst mosquitoes, it is the female who stings to get the proteins needed to make eggs. The urge to sting and ingest blood could be regulated by the same molecular brain sensor that Carlos Ribeiro now identified in Drosophila.
Carlos again, 'Maybe if we could understand how the sensor works in the Drosophila brain to control the urge to eat protein-rich food, we might be able to alter the urge of mosquito females to ingest blood and, thus, interfere with the transfer of the malaria parasite between hosts.'
Research in the fruit fly has helped unravel several mechanisms which proved to be relevant in humans, too. This study appears to be on the same track.
This study was supported by the European Molecular Biology Organisation (EMBO) the Swiss National Science Foundation, the Champalimaud Foundation and Boehringer Ingelheim GmbH.
Carlos Ribeiro followed Drosophila foraging habits for several weeks and found that fruit flies choose between different food sources according to their nutritional requirements, gender and mating status. Carlos describes their findings, 'Normally when kept on "complete food" (with sugar and yeast) and given the choice, flies do not eat food with proteins (yeast-enriched). However, after a few days on a protein-poor diet, flies preferred a yeast-rich diet. Female flies switch diets more quickly than males, and mated females quicker than virgin females.
The researchers used a simple and clever assay to follow the type of food flies preferred: they added a blue dye to the yeast-enriched food and a red dye to the 'sugar rich food', and then looked at the bellies of the flies, to know which food they had eaten.
Carlos says, 'This assay, and the powerful genetics of the fruit fly, allowed us to take the next step, and describe the molecules and neurons which make mated females react faster than virgin females, as well as the molecules which act in the brain of flies to detect a lack proteins and make the flies change their decisions -- the sensor, so to speak'.
The sensor turns out to be the same that might regulate feeding habits of both female mosquitoes and vertebrates. In humans, regulation of protein and carbohydrate uptake could be an important component of eating disorders -- a major health problem in western societies. Amongst mosquitoes, it is the female who stings to get the proteins needed to make eggs. The urge to sting and ingest blood could be regulated by the same molecular brain sensor that Carlos Ribeiro now identified in Drosophila.
Carlos again, 'Maybe if we could understand how the sensor works in the Drosophila brain to control the urge to eat protein-rich food, we might be able to alter the urge of mosquito females to ingest blood and, thus, interfere with the transfer of the malaria parasite between hosts.'
Research in the fruit fly has helped unravel several mechanisms which proved to be relevant in humans, too. This study appears to be on the same track.
This study was supported by the European Molecular Biology Organisation (EMBO) the Swiss National Science Foundation, the Champalimaud Foundation and Boehringer Ingelheim GmbH.
Saturday, May 01, 2010
NEW YORK (Reuters Health) - To help guard against the pain syndrome fibromyalgia, best to maintain a healthy weight and stay active, according to a new study from Norway.
The study in women found that being overweight or obese was associated with increased risk of fibromyalgia, especially among women who weren't all that physically active.
It is well established that maintaining a healthy lifestyle, including staying fit, trim and active helps prevent several chronic conditions such as heart disease and high blood pressure, Paul J. Mork, who led the study, noted in an email to Reuters Health.
"Our study indicates that a similar association also exists for development of" fibromyalgia," writes Mork, from the Human Movement Science Program, Norwegian University of Science and Technology in Trondheim.
Fibromyalgia is a debilitating pain syndrome that affects an estimated 2 to 4 percent of the population. It's characterized by chronic pain, often in the neck, shoulders, back, hips, arms and legs. Fatigue, depressed mood, and difficulty thinking and sleeping are other common symptoms. There is no clear-cut cause.
Mork said while an association between fibromyalgia and being overweight or obese has been shown in prior "cross-sectional" studies, his is the first forward looking, or "prospective" study to document being overweight or obese as independently raising one's risk of developing the pain syndrome.
The findings, published in the journal Arthritis Care and Research, are based on nearly 16,000 physically able, fibromyalgia-free women who were followed for 11 years. During this time, 380 developed fibromyalgia.
Overweight and obese women had a 60 percent to 70 percent higher risk of developing fibromyalgia over the study period, relative to their normal-weight counterparts, the researchers found.
They also found that women who said they exercised 4 or more times a week had a 29 percent lower risk of developing fibromyalgia compared to inactive women. A look at the number of hours exercised each week revealed that women who said they got 2 or more hours a week had a 23 percent lower risk of the pain syndrome.
In looking at the combined effects of exercise and body weight on risk of fibromyalgia, the researchers found a greater than two-fold increased risk for overweight or obese women who were either inactive or who reported exercising for 1 hour or less each week. There was no clear relationship between exercise and risk of fibromyalgia in normal-weight women.
Overall, this study found a "weak protective" effect of leisure time physical activity on future development of fibromyalgia, Mork noted. "This was somewhat unexpected and needs further exploration," he admitted.
However, Mork said it's important to note that his team was not able to differentiate between different types of exercise "and it might be possible that some exercise types are more beneficial than others in protecting against future development of fibromyalgia."
He and his colleagues conclude, based on their study and others, that maintaining a healthy weight and regular exercise are important for reducing the risk of fibromyalgia.
SOURCE: Arthritis Care and Research, May 2010.
The study in women found that being overweight or obese was associated with increased risk of fibromyalgia, especially among women who weren't all that physically active.
It is well established that maintaining a healthy lifestyle, including staying fit, trim and active helps prevent several chronic conditions such as heart disease and high blood pressure, Paul J. Mork, who led the study, noted in an email to Reuters Health.
"Our study indicates that a similar association also exists for development of" fibromyalgia," writes Mork, from the Human Movement Science Program, Norwegian University of Science and Technology in Trondheim.
Fibromyalgia is a debilitating pain syndrome that affects an estimated 2 to 4 percent of the population. It's characterized by chronic pain, often in the neck, shoulders, back, hips, arms and legs. Fatigue, depressed mood, and difficulty thinking and sleeping are other common symptoms. There is no clear-cut cause.
Mork said while an association between fibromyalgia and being overweight or obese has been shown in prior "cross-sectional" studies, his is the first forward looking, or "prospective" study to document being overweight or obese as independently raising one's risk of developing the pain syndrome.
The findings, published in the journal Arthritis Care and Research, are based on nearly 16,000 physically able, fibromyalgia-free women who were followed for 11 years. During this time, 380 developed fibromyalgia.
Overweight and obese women had a 60 percent to 70 percent higher risk of developing fibromyalgia over the study period, relative to their normal-weight counterparts, the researchers found.
They also found that women who said they exercised 4 or more times a week had a 29 percent lower risk of developing fibromyalgia compared to inactive women. A look at the number of hours exercised each week revealed that women who said they got 2 or more hours a week had a 23 percent lower risk of the pain syndrome.
In looking at the combined effects of exercise and body weight on risk of fibromyalgia, the researchers found a greater than two-fold increased risk for overweight or obese women who were either inactive or who reported exercising for 1 hour or less each week. There was no clear relationship between exercise and risk of fibromyalgia in normal-weight women.
Overall, this study found a "weak protective" effect of leisure time physical activity on future development of fibromyalgia, Mork noted. "This was somewhat unexpected and needs further exploration," he admitted.
However, Mork said it's important to note that his team was not able to differentiate between different types of exercise "and it might be possible that some exercise types are more beneficial than others in protecting against future development of fibromyalgia."
He and his colleagues conclude, based on their study and others, that maintaining a healthy weight and regular exercise are important for reducing the risk of fibromyalgia.
SOURCE: Arthritis Care and Research, May 2010.
