Australian researchers say fat is 'sixth taste'
March 8, 2010
It's a theory set to confirm why humans are so fond of fatty foods such as chips and chocolate cake: in addition to the five tastes already identified lurks another detectable by the palate -- fat.
"We know that the human tongue can detect five tastes -- sweet, salty, sour, bitter and umami (a savoury, protein-rich taste contained in foods such as soy sauce and chicken stock)," Russell Keast, from Deakin University, said Monday.
"Through our study we can conclude that humans have a sixth taste -- fat."
Researchers tested 30 people's ability to taste a range of fatty acids in otherwise plain solutions and found that all were able to determine the taste -- though some required higher concentrations than others.
They then developed a screening test to see how sensitive people were to the taste and found that, of the 50 people tested, their ability to detect fat was linked to their weight -- a finding which could help counter obesity.
"We found that the people who were sensitive to fat, who could taste very low concentrations, actually consumed less fat than the people who were insensitive," Keast told AFP.
"We also found that they had lower BMIs (Body Mass Indexes)."
Keast said the research, conducted in collaboration with the University of Adelaide, New Zealand's Massey University and Australian science body CSIRO, suggested that the taste of fat could trigger a mechanism in the body.
"We all like eating fatty foods. What we speculate is (that) the mechanism is to do with stopping eating. Your body is able to tell you you've had enough and stop," he explained.
"And if you are insensitive to it, you're not getting that feedback."
With fats easily accessible and commonly consumed, it was possible that people may become desensitised to the taste of fat, leaving some more prone to overindulging in calorie-rich foods, he added.
The results, published in the British Journal of Nutrition, have not definitively classified fat as a taste but Keast says the evidence is strong and mounting.
For something to be classified as a taste there needed to be proven receptor mechanisms on taste cells in the mouth, he said.
"We have what... we will call possible candidate receptors for fat on taste receptor cells," he said.
Thursday, 27 October 2011
Study Shows Why It’s Hard to Keep Weight Off By GINA KOLATA Published: October 26, 2011
For years, studies of obesity have found that soon after fat people lost weight, their metabolism slowed and they experienced hormonal changes that increased their appetites. Scientists hypothesized that these biological changes could explain why most obese dieters quickly gained back much of what they had so painfully lost.
GETTY IMAGES
But now a group of Australian researchers have taken those investigations a step further to see if the changes persist over a longer time frame. They recruited healthy people who were either overweight or obese and put them on a highly restricted diet that led them to lose at least 10 percent of their body weight. They then kept them on a diet to maintain that weight loss. A year later, the researchers found that the participants’ metabolism and hormone levels had not returned to the levels before the study started.
The study, being published Thursday in The New England Journal of Medicine, is small and far from perfect, but confirms their convictions about why it is so hard to lose weight and keep it off, say obesity researchers who were not involved the study.
They cautioned that the study had only 50 subjects, and 16 of them quit or did not lose the required 10 percent of body weight. And while the hormones studied have a logical connection with weight gain, the researchers did not show that the hormones were causing the subjects to gain back their weight.
Nonetheless, said Dr. Rudolph Leibel, an obesity researcher at Columbia, while it is no surprise that hormone levels changed shortly after the participants lost weight, “what is impressive is that these changes don’t go away.”
Dr. Stephen Bloom, an obesity researcher at Hammersmith Hospital in London, said the study needed to be repeated under more rigorous conditions, but added, “It is showing something I believe in deeply — it is very hard to lose weight.” And the reason, he said, is that “your hormones work against you.”
In the study, Joseph Proietto and his colleagues at the University of Melbourne recruited people who weighed an average of 209 pounds. At the start of the study, his team measured the participants’ hormone levels and assessed their hunger and appetites after they ate a boiled egg, toast, margarine, orange juice and crackers for breakfast. The dieters then spent 10 weeks on a very low calorie regimen of 500 to 550 calories a day intended to makes them lose 10 percent of their body weight. In fact, their weight loss averaged 14 percent, or 29 pounds. As expected, their hormone levels changed in a way that increased their appetites, and indeed they were hungrier than when they started the study.
They were then given diets intended to maintain their weight loss. A year after the subjects had lost the weight, the researchers repeated their measurements. The subjects were gaining the weight back despite the maintenance diet — on average, gaining back half of what they had lost — and the hormone levels offered a possible explanation.
One hormone, leptin, which tells the brain how much body fat is present, fell by two-thirds immediately after the subjects lost weight. When leptin falls, appetite increases and metabolism slows. A year after the weight loss diet, leptin levels were still one-third lower than they were at the start of the study, and leptin levels increased as subjects regained their weight.
Other hormones that stimulate hunger, in particular ghrelin, whose levels increased, and peptide YY, whose levels decreased, were also changed a year later in a way that made the subjects’ appetites stronger than at the start of the study.
The results show, once again, Dr. Leibel said, that losing weight “is not a neutral event,” and that it is no accident that more than 90 percent of people who lose a lot of weight gain it back. “You are putting your body into a circumstance it will resist,” he said. “You are, in a sense, more metabolically normal when you are at a higher body weight.”
A solution might be to restore hormones to normal levels by giving drugs after dieters lose weight. But it is also possible, said Dr. Jules Hirsch of Rockefeller University, that researchers just do not know enough about obesity to prescribe solutions.
One thing is clear, he said: “A vast effort to persuade the public to change its habits just hasn’t prevented or cured obesity.”
“We need more knowledge,” Dr. Hirsch said. “Condemning the public for their uncontrollable hedonism and the food industry for its inequities just doesn’t seem to be turning the tide.”
GETTY IMAGES
But now a group of Australian researchers have taken those investigations a step further to see if the changes persist over a longer time frame. They recruited healthy people who were either overweight or obese and put them on a highly restricted diet that led them to lose at least 10 percent of their body weight. They then kept them on a diet to maintain that weight loss. A year later, the researchers found that the participants’ metabolism and hormone levels had not returned to the levels before the study started.
The study, being published Thursday in The New England Journal of Medicine, is small and far from perfect, but confirms their convictions about why it is so hard to lose weight and keep it off, say obesity researchers who were not involved the study.
They cautioned that the study had only 50 subjects, and 16 of them quit or did not lose the required 10 percent of body weight. And while the hormones studied have a logical connection with weight gain, the researchers did not show that the hormones were causing the subjects to gain back their weight.
Nonetheless, said Dr. Rudolph Leibel, an obesity researcher at Columbia, while it is no surprise that hormone levels changed shortly after the participants lost weight, “what is impressive is that these changes don’t go away.”
Dr. Stephen Bloom, an obesity researcher at Hammersmith Hospital in London, said the study needed to be repeated under more rigorous conditions, but added, “It is showing something I believe in deeply — it is very hard to lose weight.” And the reason, he said, is that “your hormones work against you.”
In the study, Joseph Proietto and his colleagues at the University of Melbourne recruited people who weighed an average of 209 pounds. At the start of the study, his team measured the participants’ hormone levels and assessed their hunger and appetites after they ate a boiled egg, toast, margarine, orange juice and crackers for breakfast. The dieters then spent 10 weeks on a very low calorie regimen of 500 to 550 calories a day intended to makes them lose 10 percent of their body weight. In fact, their weight loss averaged 14 percent, or 29 pounds. As expected, their hormone levels changed in a way that increased their appetites, and indeed they were hungrier than when they started the study.
They were then given diets intended to maintain their weight loss. A year after the subjects had lost the weight, the researchers repeated their measurements. The subjects were gaining the weight back despite the maintenance diet — on average, gaining back half of what they had lost — and the hormone levels offered a possible explanation.
One hormone, leptin, which tells the brain how much body fat is present, fell by two-thirds immediately after the subjects lost weight. When leptin falls, appetite increases and metabolism slows. A year after the weight loss diet, leptin levels were still one-third lower than they were at the start of the study, and leptin levels increased as subjects regained their weight.
Other hormones that stimulate hunger, in particular ghrelin, whose levels increased, and peptide YY, whose levels decreased, were also changed a year later in a way that made the subjects’ appetites stronger than at the start of the study.
The results show, once again, Dr. Leibel said, that losing weight “is not a neutral event,” and that it is no accident that more than 90 percent of people who lose a lot of weight gain it back. “You are putting your body into a circumstance it will resist,” he said. “You are, in a sense, more metabolically normal when you are at a higher body weight.”
A solution might be to restore hormones to normal levels by giving drugs after dieters lose weight. But it is also possible, said Dr. Jules Hirsch of Rockefeller University, that researchers just do not know enough about obesity to prescribe solutions.
One thing is clear, he said: “A vast effort to persuade the public to change its habits just hasn’t prevented or cured obesity.”
“We need more knowledge,” Dr. Hirsch said. “Condemning the public for their uncontrollable hedonism and the food industry for its inequities just doesn’t seem to be turning the tide.”
Tuesday, 11 October 2011
Pancreatic Cancer, Diabetes Education, Vitamins, Obesity decreasing..Medical News of Interest this week
Summary of some Health News of Interest
Diabetes Education and Cognitive Change Counseling can bring about a reduction in Blood Glucose in patients struggling to control their Diabetes. Some of the reductions are equal to or better than some of the newer medications for Type 2 Diabetes.
More is not Better, a study among older women in Iowa concludes about Vitamin usage and increased mortality.
Multivitamins, Folate, Iron, Magnesium and Zinc seems to be the culprits with worse results with Iron when used without a medical reason to do so. Calcium is protective and Vitamin D is recommended for people with deficiency in Vitamin D.
Three personalities who died in the past few days all died of Pancreatic Cancer: Steve Jobs, The Nobel Prize winner in Medicine from Rockefeller U and Roger Williams the Pianist. Is there an increase in Pancreatic Cancer? Yes there is, especially in people with lifestyle pattern consistent with Ill health. Steve Jobs’ pancreatic cancer was a rare one.
One in eight, approximately, medical advances touted as bringing benefit to humanity are later withdrawn because of the wrong premises on which the studies were based. Do not be the first one to adopt a study nor be the last one to do so, is a good advice given to me at University of Miami School of Medicine.
Now the Good News is: Americans are tad less Overweight than just one year ago, now 36.6 per cent are of normal weight, one per cent higher than one year ago.
Have we succeeded in getting the message across about nutrition and exercise? Don't be so eager to accept the accolades before you realize that a sagging economy have made more people eat at home.
The take home lesson is EATING OUT IN AMERICA is dangerous to an ordinary American!
The results are in for the Science and Maths scores from around the world, the first two cities whose students came out ahead are…
Both in China
Shanghai and Hong Kong. They both recruit their teachers from the top 30 per cent of the graduate cohorts whereas in the countries in the failing grade recruits teachers from the bottom 30 per cent.
Needless to say this will have some implications on the quality of education of future health care providers. But USA is ahead of Asian 2 dollar Wal-Mart manufacturers and 1 800 Foreign Accents from India in that it is still possible to get a good all round education in the USA and not just a career oriented limited education. Hurrah for that!
Some other good news, which we in the Indian Health Services would recognize, is the value of expressive writing. Indians being much more visual people use Talking Circles in which emotions are expressed freely and openly find good results from this ritual which has also symbolic significance in their historic annals.
Dr Pennebaker from UT in Austin, a psychologist has conducted some experiments and he has concluded”
Stress, trauma, and unexpected life developments — such as a cancer diagnosis, a car accident, or a layoff — can throw people off stride emotionally and mentally. Writing about thoughts and feelings that arise from a traumatic or stressful life experience — called expressive writing — may help some people cope with the emotional fallout of such events. But it’s not a cure-all, and it won’t work for everyone. Expressive writing appears to be more effective for people who are not also struggling with ongoing or severe mental health challenges, such as major depression or post-traumatic stress disorder.
I have to admit that Talking Circle is good for people who are suffering from emotional disturbances in addition to their physical problems, such as the PTSD or depression.
Today I was sitting down to a lunch of Alaskan Haddock in Olive oil sprinkled with Zatar from Israel (mentioned in the old testament) and some cilantro and a touch of sweet pepper, and happened to be reading Archives of Internal Medicine published only yesterday and in it there were three studies in three different social contexts about the worth of diabetes education and cognitive changes that help those struggling over the years to control their diabetes. Lo and behold, the education was much better than many of the newer medications for Diabetes! Hats off to our cadre of Diabetes Educators. I rushed with the news to my colleagues who were doing just that over their lunchtime, educating a group of Indian patients with Diabetes… I shared the news with them.
The Indians had a big smile on their faces!
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