What happens to people who are thin until adulthood and then gain a lot of weight?

Every year, whether you are fat or thin, whether you lose weight or gain, 10 percent of your fat cells die. And every year, those cells that die are replaced with new fat cells. The result is that the total number of fat cells in the body remains the same, year after year throughout adulthood. Losing or gaining weight affects only the amount of fat stored in the cells, not the number of cells.


Obesity investigators say the study raises tantalizing questions: What determines how many fat cells are in a person’s body? When is that number determined? Is there a way to intervene so people end up with fewer fat cells when they reach adulthood? And could“This is a new way of looking at obesity,” said Dr. Lester Salans, an obesity researcher and emeritus professor at Mount Sinai School of Medicine in New York.

But for now, researchers say, they do not have a clue about how to answer those questions.

“There is a system waiting to be discovered,” said Dr. Jeffrey S. Flier, an obesity researcher and dean of Harvard Medical School.

Dr. Flier and other obesity researchers cautioned, though, that even if scientists knew how the fat cell system worked, it was not clear that it would be safe or effective to treat obesity by intervening. One of the hard lessons of the past couple of decades has been that the body has redundant controls to maintain weight.

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“I suspect that the body’s regulation of weight is so complex that if you intervene at this site, something else is going to happen to neutralize this intervention,” Dr. Salans said.

But the discovery is also leading to new ways to address other questions about obesity. For example, what happens to people who are thin until adulthood and then gain a lot of weight? The study focused on people who had been fat since childhood, the usual route for adult obesity. The situation may be different for people who got fat later. They may actually grow new fat cells — the ones they had may have become so stuffed with fat that they could hold no more.

Another question is whether fat cells removed with liposuction grow back.

Both questions are now under investigation by the Swedish researchers.

In a way, Dr. Flier noted, the discovery is a sort of back-to-the-future moment. There was a time a few decades ago, before the current interest in how the brain regulates how much is eaten, when obesity researchers spent all their time studying and discussing fat cells. Investigators discovered that fat people had more fat cells than thin people and that fat cells shrank with weight loss and bulged with weight gain.

Dr. Jules Hirsch of Rockefeller University in New York, who did many of the initial studies with humans, said he started because he could not understand why people who lost weight regained. “They should have been cured,” Dr. Hirsch said. After all, he said, if you cut out a fatty tumor, the fat does not grow back. Why was fat lost from dieting different?

The result was the fat cell hypothesis, a notion that obsessed researchers. Fat cells, the hypothesis said, are laid down early in life and after that, they can change only in size, not in number. When people lose weight and their fat cells shrink, that creates a signal to fill the cells again, making people regain. “We didn’t know a lot about obesity, so that was what we talked about,” Dr. Flier said.

But the discussions stalled. It was not clear what to do about those discoveries or what they meant to efforts to help people lose weight. And no one had a method to ask whether fat cells were being created and destroyed during life. Few even thought to ask that question.

That changed only recently when the new paper’s first author, Kirsty L. Spalding, a neurobiologist at the Karolinska Institute in Sweden, developed a way to ask whether new cells grow in the cortical and cerebellum regions of the human brain. She found no new cells there since birth. One day, she was giving a talk on her brain study when a scientist in the audience, Erik Arner, suggested she use the method to look at fat cells. (Dr. Arner is the second author of Dr. Spalding’s paper.) The method for dating human cells takes advantage of an effect caused by above-ground nuclear bomb testing that took place from 1955 to 1963.

When the bombs were tested, their radioactivity created a spike in the amount of a carbon isotope, C14, in the atmosphere. The C14 made its way into plants and animals that ate the plants. When people ate those plants and meat from the animals, the C14 was incorporated into their human DNA. After the nuclear test ban, C14 levels started to drop. The result is that every cell has a C14 level that reflects the level in the atmosphere at the time the cell was born.

“Each cell is a time capsule of sorts,” Dr. Spalding said.

First the researchers confirmed that the number of fat cells remained constant in adults. Obese people who had weight loss surgery had as many fat cells two years after the surgery as before it, even though they were much thinner.

Then the investigators asked whether fat cells were being born and dying. To do that, they examined fat cells taken from 35 people, fat and lean, who had had liposuction or abdominal wall reconstruction. The amount of C14 in the cells would reveal how old the cells were. Since the number of fat cells remained constant, the number being born had to equal the number dying. And a mathematical model would reveal the dynamics of the cell turnover.

“We found the cells were really quite young,” Dr. Spalding said. “That tells us new cells are being born.” She added: “The million-dollar question now is, What regulates this process? And where can we intervene?”

Source: The New York Times

Suicide attempts are "not uncommon" among people with anorexia nervosa

The risk appears to be significantly higher among those who purge rather than just restrict the amount they eat, Dr. Cynthia M. Bulik and colleagues report. Suicidal ideas and behaviors by anyone with anorexia nervosa "should not be overlooked as something that will just pass," Bulik said. Suicidal gestures "should be considered very seriously, and dealt with appropriately by a professional," she told Reuters Health.

Bulik, director of the eating disorders program at the University of North Carolina at Chapel Hill, and colleagues looked at patterns of attempted suicide among people with anorexia nervosa who enrolled in the Genetics of Anorexia Nervosa Collaborative Study.

The 413 study participants, nearly all female, ranged in age from 16 to 76 years. Almost 17 percent of the group reported at least one suicide attempt, initially occurring between 7 and 40 years of age. More than half of these cases required medical attention, the investigators report in the medical journal Psychosomatic Medicine.

Those with the restricting subtype of anorexia nervosa, defined as severe restriction of food intake but no lifetime history of binge eating or purging, appear to have the lowest risk, as the researchers found just over 7 percent of this group reported at least one suicide attempt.

By contrast, 26, 29, and 21 percent of participants with the purging, binging, and combined anorexia/bulimia subtypes reported at least one suicide attempt, the researchers note. These subtypes involve single or combined behaviors such as vomiting, laxative or diuretic abuse, and binge eating.

Besides the known association between depression and suicide risk, Bulik's group found suicide attempts were linked with additional factors such as panic disorder, post-traumatic stress disorder, substance abuse or dependence, dramatic or erratic behavior, impulse-control disturbances, and self-harm or stealing behaviors.

"This study underscores again that anorexia nervosa is a serious mental illness," Bulik concluded.

Source: MedlinePlus

Don't get jealous of your friend's dress size. It may be mostly out of your hands and in your DNA

Your friend can eat whatever she wants and still fit into her prom dress, but you gain five pounds if you just look at that chocolate cake. Before you sign up for Weight Watchers and that gym membership, though, you may want to look at some recent research from Tel Aviv University and save yourself a few hundred dollars.



A woman's waistline may have less to do with rigorous exercise and abstaining from sweets than it does with the genes of her parents, according to a new study by Prof. Gregory Livshits from the Sackler Faculty of Medicine at Tel Aviv University and colleagues from King's College in London. Dr. Livshits and his colleagues have found a scientific link between the lean body mass of a woman and her genes. They've determined that thinness -- like your smile or the color of your eyes -- is an inheritable trait.

Bad news first, then the good
Prof. Livshits, whose findings were published in the Journal of Clinical Endocrinology and Metabolism (2007), says, "The bad news is that many of our physical features, including our weight, are dependent on our genes. The good news is that women still have an opportunity to go against their genetic constitution and do something about it."

Until now, scientists were not sure to what extent environmental influences and genetics played a role in a woman's body size. When controlling for the variance of age, the differences in womens' body sizes can be predicted in the genes more than 50percent of the time, the researchers found.

Prof. Livshits conducted his study on more than 3,000 middle-aged women in the United Kingdom who belonged to either an identical or fraternal twin pair. He measured their "total lean mass," one of the three major components of body weight, and compared it to markers in their genes.

A slim chance?
Additional collaborative research between the two teams, which builds on the past study, is to be published in the next few months. It may help pave the way for a "skinny gene test," which one day may help women trying to lose weight understand what kind of battle they can expect.

Those without the lean genes, however, will always find it harder to stay slim, predicts Prof. Livshits. But before your diet falls by the wayside, consider Prof. Livshits' contention that genetics can be overcome.

Curb your enthusiasm
It's important to not have high expectations, he warns. "Women need to know that what they can do about their body weight especially when they age is relatively little, and they will do it only with much difficulty."

Very few studies to date have been able to associate a body's lean mass with genetics. The topic is a specialty at the Tel Aviv University lab, one of the top labs in the world to study the genetics of aging of body composition. This area includes the study of bone, fat and lean mass as it develops in a person over time.

Research on body composition components -- their growth, degradation and genes -- is part of Prof. Livshits' ongoing work on aging and health. Issues such as weight gain are complex, he says, especially when age is factored in.

Source: ScienceDaily

Am I Hungry? What to Do When Diets Don't Work

It's no mystery that a diet full of fried foods, giant portions, decadent desserts, alcohol, and sugary soft drinks will lead to weight gain. And there's little question why the pounds pile up when you take in more calories than you burn in physical activity. But how do you explain weight gain when your lifestyle includes regular exercise and a healthy diet that is controlled in calories?


Gaining weight is absolutely maddening, especially when you really don't understand why the needle on the scale keeps going up.

Several things should be considered if you are gaining weight while watching calories and being physically active. More than likely, it's a variety of things working together that have resulted in the weight gain.

Read this book, it explains a lot!
"Weight gain is so complicated; there are so many factors that can impact your weight. It is more likely a combination of things more than just one factor," explains Michelle May, MD, author of Am I Hungry? What to Do When Diets Don't Work

Some popular blood pressure medications may help you lose weight

Some popular blood pressure medications may help you lose weight and body fat, according to a study done in mice. Angiotensin-converting enzyme(ACE) inhibitors and angiotensin II receptor blockers are blood pressure drugs that block key steps in a system that helps control blood pressure and reduce fluid buildup in the body. This pathway is known as the renin-angiotensin system. Previous studies have suggested that the renin-angiotensin system plays a role in body fat and obesity.

Michael Mathai and colleagues in Australia examined mice that were missing a gene that encodes for angiotensin-converting enzyme, a key protein for the renin-angiotensin system. They discovered that those without the gene weighed 20% less.

The lightweight mice also had about 50% less body fat than their heavyweight counterparts, particularly in the belly area. However, both groups of mice seemed to eat and exercise the same amount, leading researchers to theorize that the slimmer mice might have a faster metabolism.

The researchers found that the ACE-deficient mice not only broke down fats faster in the liver, they processed blood sugars more quickly than the other mice, making them less likely to develop diabetes.

The study results demonstrate that an ACE deficiency leads to reduction in body fat accumulation in mice and suggests that drugs that affect the renin-angiotensin system, such as ACE inhibitors, might spark weight loss, especially in the midsection. Having a so-called spare tire around your belly is a strong risk factor for cardiovascular disease and diabetes.

Source: WebMD

Overeating is the actual cause of metabolic syndrome

Overeating, not the obesity it causes, is the actual cause of metabolic syndrome, suggests a study with mice by researchers at the University of Texas Southwestern Medical Center at Dallas. Metabolic syndrome is a collection of health factors that increase the risk of developing insulin resistance, fatty liver, heart disease and type 2 diabetes. This study was among the first to propose that weight gain is an early symptom, not a direct cause, of metabolic syndrome, the researchers said.

"Most people today think that obesity itself causes metabolic syndrome," senior author Dr. Roger Unger, professor of internal medicine, said in a prepared statement. "We're ingrained to think obesity is the cause of all health problems, when, in fact, it is the spillover of fat into organs other than fat cells that damages these organs, such as the heart and the liver. Depositing fatty molecules in fat cells where they belong actually delays that harmful spillover."

In this study, Under and his colleagues compared normal mice to mice that were genetically altered to prevent their fat cells from expanding. Both groups of mice were overfed.

The normal mice got fat but didn't develop signs of metabolic syndrome until after about seven weeks of overeating. The genetically altered mice stayed slim but became seriously ill within a few weeks and displayed evidence of severe heart problems and major increases in blood sugar levels eight weeks before minimal heart problems developed in the normal mice, the researchers said.

The genetically altered mice showed significant damage to heart cells and to the insulin-secreting cells in the pancreas. They also got sick quicker, because the extra calories they consumed weren't stored in fat cells, but rather in other tissues, the researchers said.

Source: Medline Plus

Think yourself thinner

The Daily Mail reports that you can "think yourself thinner". It says that researchers have found that "actively remembering your last meal suppresses appetite and reduces the desire to snack on junk food". It also says the study found that concentrating on food while eating makes you less likely to get hungry later on.

These results are based on three experiments in healthy young people with a normal body mass index (BMI). It's therefore not clear whether these results would apply to people who were underweight, overweight or obese. It's also not clear whether this technique would be able to reduce snacking in the longer term, or to reduce a person's overall calorie intake or weight.

Although thinking of a recent meal might help someone reduce their snacking, unless this is part of a programme that includes a healthy diet and increased physical activity, this technique seems unlikely to have much effect on weight loss.

Where did the story come from?

Dr Suzanne Higgs and colleagues from the School of Psychiatry at the University of Birmingham carried out the research. The study was funded by the Biotechnology and Biological Sciences Research Council. It was published in Physiology & Behavior, a peer-reviewed scientific journal.

What kind of scientific study was this?

In this experimental study, the researchers tested whether remembering a recent meal had an effect on snacking. They also wanted to see whether this effect varied depending on how appealing the snack was, how long ago the meal was eaten, and the person's normal eating behaviour (specifically whether or not the person was usually restrained in what they ate).

The researchers carried out three experiments. All the participants answered a questionnaire about their lifestyles, including eating behaviour. This included 10 questions about dietary restraint (attempt to restrict food intake to control body weight) and 13 questions about disinhibition (tendency to overeat in certain situations).

The first experiment involved 14 healthy male students (average age of 21) with a normal BMI (19 to 25kg/m2). Afternoon test sessions were conducted on two different days and the participants were asked to eat their lunch at least two hours before the session. At the start of the first test session, they rated their appetites and mood at that time using a visual analogue scale (VAS). The VAS scale is a 10cm-long line; its opposite ends represent the extremes of the feeling being tested.

After this, the group was split into two. One group was asked to record in as much detail as possible what they ate for lunch that day, while the other was asked to write down what they had for lunch the day before. After this, the participants again gave their appetite and mood ratings.

All the participants were presented with three bowls of popcorn with differing levels of salt (high, low, and no salt). They were then asked to rate how tasty, sweet, salty, and sour each bowl of popcorn was using a VAS scale ranging from 'not at all' to 'extremely'. They were also asked the likelihood that they would choose to eat from each bowl again. The participants were told to eat as much of the popcorn as they needed to rate its taste, and that after rating the popcorn they could eat as much of it as they liked. After the experiment was finished, the bowls of popcorn were weighed to see how much had been eaten.

On the second test day the groups switched tasks. The researchers analysed how much popcorn was eaten, taking into account what the volunteer was told to recall, how salty the popcorn was, and the order in which they were tested (i.e. whether they had to recall that day's or the previous day's lunch).

The second experiment involved 73 healthy female students (average age of 20). Using the questionnaire, the participants were given scores of their eating restraint and disinhibition and people with different combinations of these characteristics were randomly assigned to recall that day's lunch or that of the day before. They also all had an introductory day where there was no recall, and they tasted and rated the popcorn. After this, the procedure remained similar to the first experiment, but the groups were not switched. The researchers then compared the effects of different eating restraint and disinhibition scores to the results.

In the third experiment, 47 healthy female students (average age of 22) were given a standardised lunch containing 400 calories. They then completed the snack experiment, this time with three types of cookies rather than popcorn. The experiment was carried out on two days, the first occasion one hour after lunch, and the second three hours after lunch. Half of these participants were asked to recall their lunch, while the other half were asked to recall their journey to the test centre.

What were the results of the study?In the first experiment the researchers found there was no difference in appetite ratings either before or after recall, between people recalling either that day's or the previous day's lunch. Despite this, when people recalled that day's lunch they ate less popcorn than when they recalled the previous day's lunch.

Overall, people ate more salted popcorn than non-salted popcorn, and this was not affected by what meal a person had recalled. The more salt the popcorn had, the more pleasant people thought it tasted, and again this was not significantly affected by what meal a person had recalled.

In the second experiment they found that a person's normal eating restraint did not affect how much they ate, but that only people who had low disinhibition scores (i.e. did not have a tendency to overeat) reduced their intake after recalling today's lunch.

What interpretations did the researchers draw from these results?

The researchers concluded that recalling that day's lunch reduced consumption of both low and high calorie snacks (popcorn or cookies). This was not related to how pleasant the snack tasted, and seemed to be greatest in people who did not have a tendency to overeat, and appeared to depend on memory, as there was a delay before recall had an effect.

What does the NHS Knowledge Service make of this study?

This was a small study that looked at the effect of recent meal recall on snacking. There are a number of limitations to consider:

- All of the participants were healthy young people, with BMIs in the normal range. It's not clear whether the same effect would be seen in older people or children, people who were less healthy, or people outside of the normal BMI range.

- This study only looked at the effects of meal recall on snacking in the short term. It's not clear whether this technique could reduce snacking if used on a regular basis, or whether the reductions in snacking seen would have any effect on a person's overall calorie intake or weight.

Reducing weight is difficult for some people, and thinking of a recent meal might help them reduce their snacking. However, unless this is part of a programme that includes a healthy diet and increased physical activity, this technique seems unlikely to have much effect.

Source: The Daily Mail