Diet foods might cause kids to overeat Mon Aug 13, 12:34 PM ET
NEW YORK (Reuters Health) - The diet sodas and snacks so popular with weight-conscious adults may backfire in children, if new animal research is correct.
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In experiments with juvenile rats, researchers at the University of Alberta in Canada found that animals that became used to diet foods tended to overeat during meals of regular-calorie animal chow.
This was true for normal-weight and obese rat pups, the researchers found. However, diet foods did not appear to have an overeating effect in adolescent rats.
This suggests that the foods have some unique effect in young animals, and possibly children, the study authors report in the journal Obesity.
They suspect that diet foods disrupted the young animals' ability to learn how various flavors correlate with calories. When they associate tastes, such as sweet or salty, with few calories, even a rich dessert may fail to fill them up as it otherwise would.
It's possible that children given artificially low-calorie snacks and diet sodas might not learn to properly regulate their food intake, according to lead study author Dr. W. David Pierce.
"One thing is clear at this point," he said in a statement. "Young animals and perhaps children can be made to overeat when calorie-wise foods are offered on a daily basis, subverting the body's energy-balance system."
He and his colleagues recommend that parents give their children a well-balanced diet of foods in their natural form, including naturally low-calorie foods like fruits and vegetables.
The findings are based on a series of experiments with young rats, both normal, lean animals and those genetically prone to obesity. Over 16 days, the animals were regularly given gelatin cubes that contained starch, as well as a starch-free "diet" version of the snack.
For some animals, the starchy cubes were flavored with an artificial sweetener and the diet version was flavored with a salty solution. These flavors were reversed for other animals.
After 16 days of this taste training, the researchers gave all the animals a high-calorie snack dipped in either artificial sweetener or a salty solution. They then gave the rats a meal of their regular chow.
Pierce's team found that the animals tended to overeat during the meal if their pre-meal snack had been dipped in a flavor they'd learn to associate with a low-calorie food -- despite the snack's actual high calorie content.
The phenomenon was seen in both lean and obesity-prone rat pups, but the heavier animals generally ate more than their normal-weight counterparts, the researchers point out.
So it's possible, they say, that diet foods could be especially detrimental in the children already at the greatest risk of long-term weight problems.
SOURCE: Obesity, August 2007.
http://news.yahoo.com/s/nm/diet_foods_dc
Showing posts with label Diet. Show all posts
Showing posts with label Diet. Show all posts
Wednesday, August 15, 2007
Do Diet Foods Lead to Weight Gain?
Do Diet Foods Lead to Weight Gain?
Wednesday, Aug. 08, 2007 By ALICE PARK Lowered carbohydrate snack foods.
Scott Olson / Getty
Article ToolsPrintEmailReprintsSphereAddThisRSS If you think you're cutting calories by eating diet or low-calorie versions of your favorite foods, think again. A new study by Canadian scientists published in the journal Obesity suggests that our bodies can't be fooled that easily.
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Led by David Pierce, researchers at the University of Alberta studied the eating habits of young rats, and found that they tended to overeat when they were fed "diet" foods. Though the new study was conducted in animals, it adds to a growing body of research in humans that suggests a diet-foods paradox: the more low-calorie (or even zero-calorie) sodas and foods you consume, the more your body demands payback for the calories it was deprived.
Pierce and his team started with the assumption that animals, and young animals in particular, are adapted to crave high-calorie foods that are packed with fat and carbohydrates, the crucial biological fuel that rapidly growing juveniles need. Using classic Pavlovian conditioning techniques, Pierce trained his rats to associate low-calorie foods with a "diet" taste, and high-calorie foods with a different taste. So, when the rats were fed a high-calorie food that had been flavored with the diet taste, their brains assumed that their bodies were running low on calories. These animals then overate at their next meal in an effort to refuel and make up for the lost energy. "Animals have the ability to sense the caloric value of food they take in," says Pierce. "We found out that an animal can learn to use flavors to predict calories in an attempt to achieve energy balance."
This same phenomenon could explain similar results in recent studies of dieters, says Pierce. Two years ago, scientists at the University of Texas reported in an eight-year study that for every can of diet soda that a person drank, he raised his risk of being overweight by 41%, compared to a 30% increase in drinkers of regular, sugared drinks. Earlier this year, another study of diet-soda drinkers came to a similar conclusion, this time about metabolic syndrome, the dangerous constellation of risk factors, such as obesity, high cholesterol and insulin resistance, that increases the likelihood of heart disease. In this report, part of the 60-year-old Framingham Heart Study, researchers found that soda drinkers, regardless of whether they consumed diet or regular beverages, had a 48% higher risk of metabolic syndrome than non-soda drinkers.
At the time, even the study authors conceded that it was impossible to implicate diet drinks completely, since it's possible that those who drank low-calorie beverages were already overweight or at higher risk of metabolic syndrome, and chose the diet drinks in an effort to get healthier. But Pierce's work hints that a more basic, biological mechanism may be at work. The animals in his study were able to predict the amount of calories in a food based on taste, demonstrating that the body uses cues like taste and texture to make sure it's getting enough fuel. Just as Pierce's rats were fooled into thinking they hadn't absorbed enough calories after eating diet chow, people are preprogrammed to anticipate sugary, high-calorie fulfillment when drinking a soda or noshing on a sweet-tasting snack. So, the diet versions of these foods may leave them unsatisfied, driving them to eat more to make up the difference.
All of this emerging work could make the food and beverage industry, which has invested billions in diet and low-calorie versions of almost every food imaginable, a bit uneasy. "This study simply defies common sense," wrote Dr. Richard Adamson, scientific consultant to the American Beverage Association, in a prepared statement responding to the study. "To suggest that foods and beverages with zero calories contribute to weight gain contradicts the overwhelming body of scientific evidence that supports that they can help you reduce calories and maintain a healthy weight."
Dr. Ramachandran Vasan, lead author of the Framingham study, however, notes, "A zero-calorie drink could produce a metabolic response if it is sweet. It can condition you to develop a preference for sweet things, which can lead to weight gain or metabolic syndrome. So something that is sweet could produce a metabolic effect even if it doesn't have a whole lot of calories.
"
Of course, none of the studies has yet proved that diet foods or beverages actually cause weight gain or heart disease; they have merely found an intriguing association, which scientists are still trying to explain. Well, nobody ever said counting calories was easy.
http://www.time.com/time/health/article/0,8599,1650860,00.html
Wednesday, Aug. 08, 2007 By ALICE PARK Lowered carbohydrate snack foods.
Scott Olson / Getty
Article ToolsPrintEmailReprintsSphereAddThisRSS If you think you're cutting calories by eating diet or low-calorie versions of your favorite foods, think again. A new study by Canadian scientists published in the journal Obesity suggests that our bodies can't be fooled that easily.
Related Articles
Obesity Is Contagious, Study Finds
Research shows that who you're friends with can have a profound impact on whether you're overweight
Hooked on McDonald's at Age 3
Given a choice, toddlers say the same food tastes better if it comes out of a McDonald's bag. Nutritionists don't find that such a Happy Meal
Next Year‘s Diet Books
Low carb. High fiber. No sugar. Reduced fat. Points. Exchanges. "Everything that you can think of ha...
A Feast of Diet Books
You‘ve heard of the South Beach diet. Now get ready for the latest pound-shedding plans from Sonoma ...
Dr. Andrew Weil's Wellness Diet
OVERVIEW: Aim for variety, and include as much fresh food as possible in your diet. Minimize your co...
Low-Carb Really Can Be Heart Healthy
Pass the avocado! Scientists from the Harvard School of Public Health last week announced the result...
Led by David Pierce, researchers at the University of Alberta studied the eating habits of young rats, and found that they tended to overeat when they were fed "diet" foods. Though the new study was conducted in animals, it adds to a growing body of research in humans that suggests a diet-foods paradox: the more low-calorie (or even zero-calorie) sodas and foods you consume, the more your body demands payback for the calories it was deprived.
Pierce and his team started with the assumption that animals, and young animals in particular, are adapted to crave high-calorie foods that are packed with fat and carbohydrates, the crucial biological fuel that rapidly growing juveniles need. Using classic Pavlovian conditioning techniques, Pierce trained his rats to associate low-calorie foods with a "diet" taste, and high-calorie foods with a different taste. So, when the rats were fed a high-calorie food that had been flavored with the diet taste, their brains assumed that their bodies were running low on calories. These animals then overate at their next meal in an effort to refuel and make up for the lost energy. "Animals have the ability to sense the caloric value of food they take in," says Pierce. "We found out that an animal can learn to use flavors to predict calories in an attempt to achieve energy balance."
This same phenomenon could explain similar results in recent studies of dieters, says Pierce. Two years ago, scientists at the University of Texas reported in an eight-year study that for every can of diet soda that a person drank, he raised his risk of being overweight by 41%, compared to a 30% increase in drinkers of regular, sugared drinks. Earlier this year, another study of diet-soda drinkers came to a similar conclusion, this time about metabolic syndrome, the dangerous constellation of risk factors, such as obesity, high cholesterol and insulin resistance, that increases the likelihood of heart disease. In this report, part of the 60-year-old Framingham Heart Study, researchers found that soda drinkers, regardless of whether they consumed diet or regular beverages, had a 48% higher risk of metabolic syndrome than non-soda drinkers.
At the time, even the study authors conceded that it was impossible to implicate diet drinks completely, since it's possible that those who drank low-calorie beverages were already overweight or at higher risk of metabolic syndrome, and chose the diet drinks in an effort to get healthier. But Pierce's work hints that a more basic, biological mechanism may be at work. The animals in his study were able to predict the amount of calories in a food based on taste, demonstrating that the body uses cues like taste and texture to make sure it's getting enough fuel. Just as Pierce's rats were fooled into thinking they hadn't absorbed enough calories after eating diet chow, people are preprogrammed to anticipate sugary, high-calorie fulfillment when drinking a soda or noshing on a sweet-tasting snack. So, the diet versions of these foods may leave them unsatisfied, driving them to eat more to make up the difference.
All of this emerging work could make the food and beverage industry, which has invested billions in diet and low-calorie versions of almost every food imaginable, a bit uneasy. "This study simply defies common sense," wrote Dr. Richard Adamson, scientific consultant to the American Beverage Association, in a prepared statement responding to the study. "To suggest that foods and beverages with zero calories contribute to weight gain contradicts the overwhelming body of scientific evidence that supports that they can help you reduce calories and maintain a healthy weight."
Dr. Ramachandran Vasan, lead author of the Framingham study, however, notes, "A zero-calorie drink could produce a metabolic response if it is sweet. It can condition you to develop a preference for sweet things, which can lead to weight gain or metabolic syndrome. So something that is sweet could produce a metabolic effect even if it doesn't have a whole lot of calories.
"
Of course, none of the studies has yet proved that diet foods or beverages actually cause weight gain or heart disease; they have merely found an intriguing association, which scientists are still trying to explain. Well, nobody ever said counting calories was easy.
http://www.time.com/time/health/article/0,8599,1650860,00.html
Sunday, March 4, 2007
Harvardian Lifestyle Surveyed, Compared
Search the Gazette
HOME : Science Prev issues | Contact us | Harvard News Office
Current Issue:
October 04, 2001
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HARVARD GAZETTE ARCHIVES
Study finds Harvard students healthier than peers
By William J. Cromie
Gazette Staff
Students at Harvard drink more, smoke less, and have less sex than students at other colleges, according to the first nationwide survey of college lifestyles and health behaviors. Harvardians also are more depressed, get into fewer fights, and are slightly more likely to be homosexual or bisexual.
The American College Health Association did the survey by sending questionnaires to 28 schools last year; 16,024 undergraduate students responded including 904 from Harvard.
"We were pleased to see that we are no worse and slightly better than other schools," said David Rosenthal, director of Harvard's University Health Services (UHS).
Slightly more than 75 percent of Harvard students described their health as excellent or very good, compared with 61 percent of the national sample.
"Smoking is a problem," admitted Rosenthal. Although only 15.6 percent of Harvard students said they smoke, compared with 25.3 percent nationally, "I was surprised at the large number of our students who smoke," he said.
"We see smoking increasing as students move from their freshman to their senior year," noted Michael Hoyt, coordinator of health resources at UHS. "This is a huge issue because students are at the age where they're starting to form lifetime habits."
"Alcohol is also a big issue," Rosenthal said. Slightly more than 72 percent of Harvard students reported drinking alcohol in the 30 days before completing the questionnaire, compared with the national average of 68 percent.
"The thing that keeps me up at night is concern about students injuring themselves or others after drinking too much," Rosenthal noted.
About 8 percent of Harvard students reported driving after drinking. Fourteen percent admitted injuring themselves as a consequence of drinking, compared with 17 percent nationally. Two percent said they injured another person, compared with more than 4 percent nationally. At Harvard, 30 percent of the drinkers forgot where they were or what they did at times; the national average was 28 percent.
Alcohol use affected the academic performance of 5.5 percent of students at Harvard, versus 7.9 percent nationally, according to the survey.
Drinking and sex
Drinking that leads to unwanted sex is a problem on every campus. One percent of Harvard's female undergraduates reported use of force or threats of force to have sex, less than half the 2.3 percent national average.
At Harvard, 0.8 percent of the women reported they were raped, compared with 1.8 percent nationally. "The 0.8 percent amounts to 52 students," Hoyt pointed out. He noted that less than a half-dozen rapes were actually reported. "That is the kind of information we need in our efforts to get the number down to zero."
Thirty-nine percent of Harvard males and females said they had no sex partners within the past school year, compared with 29 percent of males and 27 percent of females nationally. Five percent of Harvard men and women reported having four or more partners in the past school year, compared with national numbers of 11 percent and 5 percent, respectively.
At Harvard, 2.6 percent of students describe themselves as gay or lesbian versus 1.4 percent nationally. For bisexuality, the numbers are 2.2 versus 1.5 percent. Some students said they were "not sure" of their sexual orientation - 1.7 percent at Harvard, 1.5 percent nationally.
Living away from home and meeting academic standards can be stressful for many students. Nationally, 23 percent reported they have been diagnosed with depression within the past year, as opposed to 34 percent at Harvard. Approximately 34 percent of the Harvardians are in therapy or taking medication for depression, versus about 19 percent nationally.
Rosenthal attributed the higher numbers of those in treatment to a Harvard outreach program begun last year. "We have the students watching out for each other," he noted. "The faculty - even dining-service workers - are alert for signs of depression. And we have increased the number and hours of availability of mental health professionals."
Rosenthal also expressed concern about diet and physical activity on campus. More than a quarter of Harvard students (29 percent of the males, 21 percent of the females) said they are overweight. Two percent checked "very overweight" on the questionnaire. Forty-two percent of Harvard students, and 50 percent of students nationally are exercising to lose weight; for dieting the numbers are 23 and 26 percent.
Harvard has been working to improve all its numbers, said Hoyt and Rosenthal. "Surveys like this one provide us with information we need to spot trends and to evaluate the health services we provide," Hoyt noted.
"Our numbers are good," added Rosenthal, "but we still have a great deal to do."
--------------------------------------------------------------------------------
Copyright 2002 by the President and Fellows of Harvard College
HOME : Science Prev issues | Contact us | Harvard News Office
Current Issue:
October 04, 2001
News
News, events, features
Science/Research
Latest scientific findings
Profiles
The people behind the university
Community
Harvard and neighbor communities
Sports
Scores, highlights, upcoming games
On Campus
Newsmakers, notes, students, police log
Arts
Museums, concerts, theater
Calendar
Two-week listing of upcoming events
HARVARD GAZETTE ARCHIVES
Study finds Harvard students healthier than peers
By William J. Cromie
Gazette Staff
Students at Harvard drink more, smoke less, and have less sex than students at other colleges, according to the first nationwide survey of college lifestyles and health behaviors. Harvardians also are more depressed, get into fewer fights, and are slightly more likely to be homosexual or bisexual.
The American College Health Association did the survey by sending questionnaires to 28 schools last year; 16,024 undergraduate students responded including 904 from Harvard.
"We were pleased to see that we are no worse and slightly better than other schools," said David Rosenthal, director of Harvard's University Health Services (UHS).
Slightly more than 75 percent of Harvard students described their health as excellent or very good, compared with 61 percent of the national sample.
"Smoking is a problem," admitted Rosenthal. Although only 15.6 percent of Harvard students said they smoke, compared with 25.3 percent nationally, "I was surprised at the large number of our students who smoke," he said.
"We see smoking increasing as students move from their freshman to their senior year," noted Michael Hoyt, coordinator of health resources at UHS. "This is a huge issue because students are at the age where they're starting to form lifetime habits."
"Alcohol is also a big issue," Rosenthal said. Slightly more than 72 percent of Harvard students reported drinking alcohol in the 30 days before completing the questionnaire, compared with the national average of 68 percent.
"The thing that keeps me up at night is concern about students injuring themselves or others after drinking too much," Rosenthal noted.
About 8 percent of Harvard students reported driving after drinking. Fourteen percent admitted injuring themselves as a consequence of drinking, compared with 17 percent nationally. Two percent said they injured another person, compared with more than 4 percent nationally. At Harvard, 30 percent of the drinkers forgot where they were or what they did at times; the national average was 28 percent.
Alcohol use affected the academic performance of 5.5 percent of students at Harvard, versus 7.9 percent nationally, according to the survey.
Drinking and sex
Drinking that leads to unwanted sex is a problem on every campus. One percent of Harvard's female undergraduates reported use of force or threats of force to have sex, less than half the 2.3 percent national average.
At Harvard, 0.8 percent of the women reported they were raped, compared with 1.8 percent nationally. "The 0.8 percent amounts to 52 students," Hoyt pointed out. He noted that less than a half-dozen rapes were actually reported. "That is the kind of information we need in our efforts to get the number down to zero."
Thirty-nine percent of Harvard males and females said they had no sex partners within the past school year, compared with 29 percent of males and 27 percent of females nationally. Five percent of Harvard men and women reported having four or more partners in the past school year, compared with national numbers of 11 percent and 5 percent, respectively.
At Harvard, 2.6 percent of students describe themselves as gay or lesbian versus 1.4 percent nationally. For bisexuality, the numbers are 2.2 versus 1.5 percent. Some students said they were "not sure" of their sexual orientation - 1.7 percent at Harvard, 1.5 percent nationally.
Living away from home and meeting academic standards can be stressful for many students. Nationally, 23 percent reported they have been diagnosed with depression within the past year, as opposed to 34 percent at Harvard. Approximately 34 percent of the Harvardians are in therapy or taking medication for depression, versus about 19 percent nationally.
Rosenthal attributed the higher numbers of those in treatment to a Harvard outreach program begun last year. "We have the students watching out for each other," he noted. "The faculty - even dining-service workers - are alert for signs of depression. And we have increased the number and hours of availability of mental health professionals."
Rosenthal also expressed concern about diet and physical activity on campus. More than a quarter of Harvard students (29 percent of the males, 21 percent of the females) said they are overweight. Two percent checked "very overweight" on the questionnaire. Forty-two percent of Harvard students, and 50 percent of students nationally are exercising to lose weight; for dieting the numbers are 23 and 26 percent.
Harvard has been working to improve all its numbers, said Hoyt and Rosenthal. "Surveys like this one provide us with information we need to spot trends and to evaluate the health services we provide," Hoyt noted.
"Our numbers are good," added Rosenthal, "but we still have a great deal to do."
--------------------------------------------------------------------------------
Copyright 2002 by the President and Fellows of Harvard College
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