What You Don't Know About Fat

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alternative_medicine_forum From: Frank Sat, 21 Aug 2004 05:15:31 -0700 (PDT) What You Don't Know About Fathttp://www.msnbc.msn.com/id/5709350/site/newsweek/print/1/displaymode/1098What You Don't Know About FatFat cells: The average person has 40 billion of them.They multiply, they're almost impossible to kill andthey're sending messages to your body that can ruinyour health.By Anne Underwood And Jerry AdlerNewsweekAug. 23 issue - It was one of the biggest medicalstories of the 1990s and, consequently, one of thebiggest disappointments. In 1994, researchers atRockefeller University, working with mutant mice thatgrew to be three times the size of normal ones,discovered what made them different: the absence of

ahormone they named "leptin." When injected with leptinthe mice suddenly changed their eating habits andbegan shedding those unsightly grams. Not sinceCharles Atlas had there been such a convincing set ofbefore-and-after pictures; to millions of Americanswho secretly identified with the tangerine-size ballsof fur, leptin seemed like the long-soughtwillpower-in-a-pill. But what worked in mice didn'twork in people—or, rather, it worked only in a handfulof people who, like the mice, lacked the gene toproduce leptin on their own. For a young woman inEngland who had weighed 207 pounds at the age of 9, ithas been a lifesaver. For everyone else who thought itmight succeed where low-carb diets, low-fat diets,Slim-Fast and Richard Simmons had failed, it's been abust.It was a bust because obesity researchers are upagainst a phenomenally complex and robust system,devised by evolution precisely for the purpose

ofhoarding fat against the certainty of future famine.The search for a simple cure for obesity failed fordecades, in part because researchers regarded fat asmerely the product of an equation whose other termswere greed and guilt. Now they recognize fat tissue asa discrete, active organ in its own right,continuously exchanging messages with the rest of thebody by way of the bloodstream. The messages are,generally, of two kinds: either "I'm full" or "Isn'tthere a Wendy's two-for-one coupon in the glovecompartment?We like to think that eating is avoluntary act," says Dr. Michael Schwartz of theUniversity of Washington. "But the amount you eat iscontrolled in part by how much fat you have."The search for a simple cure for obesity is stillfailing. Ask any researcher, no matter how esoterichis specialty, for the best way to lose weight and hewill reply, "Eat less and exercise more." But now wehave a much

better understanding of why the search isso difficult—and where we should look, not just totreat obesity as such, but also to recognize that somepeople are likely to stay fat to minimize the negativeeffects on their health.The work begins at the level of the fat cell itself, aglistening oleaginous sphere so tiny that it takes amillion of them to store the calories in a Life Saver,yet functioning like little chemical factoriescontinually absorbing or releasing substances inresponse to the body's energy needs. "Few systems aremore critical to survival," says Dr. Rudolph Leibel ofColumbia, than the energy storage-and-managementsystem that includes not just fat but the brain,stomach, liver, pancreas and thyroid. The problem, ofcourse, is that the system evolved millions of yearsbefore the first food court made its appearance onearth. That, says Bruce Spiegelman of the HarvardMedical School, is why it is so much

easier for mostpeople to gain weight than to lose it: "For most ofevolution, getting enough to eat was a driving forcefor survival. How many individuals were lost to morbidobesity?"When calorie intake exceeds expenditures, fat cellsswell, to as much as six times their minimum size, andbegin to multiply, from 40 billion in an average adultup to 100 billion, the threshold to get your pictureon the front page of the supermarket tabloids. (Losingweight causes them to shrink in size and become lessmetabolically active, but their number goes down onlyslowly, if at all.) Some of the resulting problems arefamiliar, and essentially mechanical. Fat requires acopious supply of blood in tiny capillaries (comparedwith an equal weight of lean muscle, which is suppliedby larger blood vessels); this puts a strain on thecardiovascular system. Obesity creates wear on thejoints, leading to osteoarthritis. The accumulation

offat around the windpipe can interfere with breathingwhen muscles relax in sleep. And fat discouragesexercise by reminding the brain: no way am I going outof doors in a jogging suit, unless there's a blackout.But the discovery of leptin helped create a paradigmshift: increasingly, researchers believe that thebiochemistry of fat holds clues both to its tenacityand to the diseases associated with obesity, includingheart disease, diabetes and even certain cancers.Leptin is one of a half-dozen or so chemicalmessengers produced by fat cells, including thrombotic(pro-clotting) agents, vasoconstrictors (which raiseblood pressure) and both inflammatory andanti-inflammatory agents that have powerful effectsthroughout the body. It just goes to show, says Dr.Gokhan Hotamisligil of the Harvard School of PublicHealth, "in the human body, as in the world, if youcontrol fuel resources, you influence a lot of

otherthings as well."CONTINUED>>Page 2: The Implications of Fat Placement in the BodyPage 3: Will Leptin Lead a Shortcut Path to WeightLoss?© 2004 Newsweek, Inc.URL: http://www.msnbc.msn.com/id/5709350/site/newsweek/