Now sit down. Read this article. And obey yourself.
Many thanks.
LD.
REF: MSN Health & Fitness - Health Topic
Content provided by Forbes.com
February 1, 2010
Diseases & Conditions: Health Topics
Content provided by:
Obesity's Hazards And Mysteries
What research tells us about why we gain weight and how we can best lose it.
By Rebecca Ruiz, Forbes
Americans are fatter than ever and it's seriously harming our health. More than 72 million adults are obese, and that figure is expected to soar to 103 million by 2018. The problem is so bad that it could even cause life expectancy to start to decline, according to some demographers.
The good news is that basic research is helping scientists understand why we eat too much and how we can best lose weight. One major finding from earlier this year is that human adults have stores of calorie-burning brown fat, long thought to exist only in newborns and certain animals. But it turns out to also be present in small quantities in adults.
Stats: Obesity By The Numbers
Harnessing brown fat could make our bodies far more efficient at burning calories--someday. But it will be years, if ever, before researchers figure out a way to increase levels of brown fat in obese adults through drugs, surgery, or some other yet-to-be discovered process.
In the meantime, researchers are investigating the basic mechanisms behind metabolism and dieting (obesity is linked to several related problems, such as diabetes, which can lead to other problems such as kidney disease or stroke). One recent study in mice hinted that eating meals on a regular schedule may be as important as what you eat or when during the day you eat. The second linked compulsive eating to a stress molecule that is commonly triggered during the withdrawal-relapse cycles of drug abusers.
Watching the Clock
Dietitians have long recommended regular mealtimes for their patients. Satchidananda Panda, an assistant professor at the Salk Institute for Biological Studies, now has laboratory data backing up this idea. His study, published in a November issue of the Proceedings of the National Academy of Sciences, showed that mice on a regular feeding schedule have much more efficient metabolisms than critters who are allowed to eat whenever they want.
Panda let one group of mice eat freely throughout the 24-hour day while another group was fed on a rigid schedule. The second group fasted for 16 hours a day, but both groups of mice ate the same amount of calories for two weeks. Then he did gene scans on the mice to see what was going on in their livers.
In the mice on the uncontrolled feeding schedules, food metabolism genes in the liver were chaotic because the mice were frequently eating and nibbling. Overall, nearly 3,000 liver genes involving in burning fat and sugar were expressed in the freely-eating mice throughout the day.
While it might seem advantageous to have thousands of calorie-burning genes running throughout the day, this makes metabolism less efficient and can create a byproduct that attacks and breaks down DNA, Panda says.
By contrast, the mice on a controlled feeding schedule had a much more consistent pattern of liver gene expression. When feeding, the mice burned sugar, but fat-burning didn't occur until several hours after they had begun fasting.
Panda says the research supports the idea that people should abstain from eating eight to 12 hours each day. Panda's research also suggests that it's possible to reset the body's metabolism simply by changing mealtimes (and fasting periods) and sticking to them. The study results convinced Panda to eat only between 8 a.m. and 8 p.m. He eats whatever he wants--with a focus on nutritious foods--and says he's lost weight since he started the regimen a year ago.
Addicted to Food
Pietro Cottone, pharmacologist at the Boston University School of Medicine, has laboratory data that may explain why some people---like himself--are prone to yo-yo dieting. If his rat experiments are correct, it may be that abstaining from sugary foods can actually trigger chemical withdrawal symptoms.
In Cottone's study, which appeared in PNAS in late November, one group of rats was fed "palatable", or high-sugar, chow for two days and then deprived of it for five days. Eventually, the withdrawal of the high-sugar chow triggered the release of a molecule known as corticotropin-releasing factor, or CRF, which causes anxious and depressive feelings and has been linked to relapses in drug addicts.
When exposed again to the palatable chow, the stressed mice overate compulsively in what Cottone characterized as "self-medication." After seven weeks, Cottone and his fellow researchers blocked the rats' CRF receptors. Only then were the rats able to restrain their anxious behavior and binging.
The scenario is no surprise to those who struggle with dieting. Cottone's goal is to prove that palatable foods are indeed biologically "addictive" and that dieters who flame-out are struggling with more than just a failure of willpower. (The threats of increased heart disease, cancer and arthritis risk sometimes aren’t enough on their own.) The only solution to the withdrawal and relapse cycle, he says, might be to avoid "palatable" foods in the first place.
Studies like Cottone's and Panda's give us much-needed insight into the biological mechanisms of metabolism and dieting, but they also require a forward-looking solution. Dr. Michael L. Power, author of The Evolution of Obesity, says humans evolved with limited access to food and have a biological drive to gorge when easy calories are available. How we cope with this is the challenge of our times, Power says. "We need to understand our biological adaptations and change our social reactions."
Why Skipping Exercise Can Be Deadly
Rebecca Ruiz, 10.06.09, 10:30 AM EDT
Recent studies show how neglecting your weight and fitness has serious consequences for your health.
In Depth: Why Skipping Exercise Can Be Deadly
One day in the summer of 2001, Dan Radin decided to run to the end of his block. For many, that short distance might be conquered in a minute or two. But Radin, a 21-year-old who weighed nearly 275 pounds at the time, barely made it--and hobbled back to his doorstep. Yet, he refused to quit and increased his distance daily; it was three months before he ran a mile, but the challenge changed his life.
Now, Radin, a marketing copywriter in Los Angeles, exercises for an hour most days of the week. He is a lean, muscular 170 pounds. At an annual checkup, his physician remarked that his low blood pressure and cholesterol were likely an improvement from even before he gained excess weight in the late 1990s.
"Losing a lot of weight and changing your body has a profound impact," Radin says.
More than he may expect, it turns out. According to a study of more than 4,300 people published this summer in the journal of the American College of Sports Medicine, the least-fit individuals had a three-fold increased all-cause mortality risk and a nearly four-fold increased cardiovascular mortality risk when compared to the most fit. In other words, improving your fitness level can better your chances for a longer life.
That study is just one in a recent spate of research in children and adults that draws connections between physical inactivity or obesity and poor health outcomes. It’s no secret that exercise is critical to excellent health, but many of us let the week slip by with nothing more than a brisk walk to the parking lot. Yet, neglecting one's weight and fitness is a certain path to increased risk for life-shortening ailments and conditions.
While physical activity is just one component of developing fitness--the others include overall health and genetic predisposition--exercise is essential.
The ideal amount, says Jonathan Myers, Ph.D., a co-author of the ACSM study and a health research scientist at the VA Palo Alto Health Care System in northern California, is a half-hour of moderate-intense activity five days of the week. Even better is an hour of exercise most days of the week.
When Myers and his co-authors separated their 4,300 participants into different fitness quintiles and studied them for nearly 20 years, the ones that performed the best reached that five-hour-a-week threshold. Those with the poorest fitness had a three-fold increase in overall mortality risk; 170 participants in this category died of all causes while only 55 in the highest quintile died.
"We've been chasing this for the last 20 years or so," Myers says of the results, "and we've seen it over and over again." Fifty years of epidemiological studies, he says, have demonstrated that people who are more fit or are more physically active have lower mortality rates.
A study published last week in the British Medical Journal found a similar correlation between weight gain and maintaining optimal health into old age. Of the 17,000 women who participated in the 20-year observational study, those who were overweight at age 18 and gained more than 22 pounds by 50 had the worst odds for optimal health. For every 11 pounds gained during that time, the chances for "healthy survival" decreased by 5%.
But it’s never too late to start exercising. Myers' research shows that there are tremendous benefits to be had for the worst-off individuals who can change their ways. When the co-authors compared the least-fit group to the next least-fit group, they noticed a striking difference: The two-fold increase in mortality risk was predominantly due to variations in physical activity, not other risk factors like hypertension and diabetes.
"We don't know yet why exercise has such protective benefits," says Myers, "but your fitness level can outperform the traditional risk factors"--such as smoking and high blood pressure--"in predicting mortality."
The Kids Aren't Alright
Though fitness often becomes a major concern in adulthood, when aging and the onset of chronic disease makes exercise imperative, there's increasing evidence that physical activity in childhood has significant long-term implications for health.
Kathleen F. Janz, a professor in the departments of Health and Sport Studies and Epidemiology at the University of Iowa, found in a recent study that children who lead less active lives are more likely to be overweight years later.
Janz studied 333 5 year olds over eight years by monitoring their physical activity with a device known as an accelerometer and measuring the subjects’ fat mass with body imaging. The protective benefit of physical activity, according to Janz and her co-authors, continued through childhood; the most active children at age five had significantly lower fat mass at eight and 11 compared with those in the lowest quartile.
"It's not unusual that there are windows of opportunity for critical periods where it's most important to do it right," says Janz. Childhood is one of them, she adds.
It's not just fatness that matters, either. A recent study in Circulation found that some Type 2 diabetic and obese teenagers have a thicker carotid artery, an association that had only been seen previously in adults and one that may put them at greater risk for stroke and heart attacks later in life.
Yet, like Jonathan Myers at the Palo Alto Health Care System in northern California, Janz says the protective benefits of exercise are immediate, regardless of how long it's been since the last workout. Certainly, Dan Radin considers himself an example of what can be accomplished with enough determination and direction.
"I hadn't grown up playing sports," he says. "Exercising was something I had to figure out."
But he's far beyond using the corner block as a benchmark or gateway to a longer, healthier life; his next target is a triathlon.
