December 15, 2009

USA: Americans are fatter than ever and it's seriously harming their health

. NEW YORK, NY / Forbes Magazine / Staying Healthy / December 15, 2009 By Rebecca Ruiz It's no secret that being overweight is unhealthy. But weight gain and loss are complicated processes, not just about diet and exercise. 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 In Depth: Seven Ways Obesity Is Making You Sicker 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. Sorry, No Magic Pill for Obesity 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." [rc] Sources: Centers for Disease Control and Prevention; American Public Health Association; Journal of the American College of Cardiology; American Heart Association; New England Journal of Medicine; Health Affairs. 2009 LLC™