瘦素可以保持更好的减肥的关键

纽约，NY-AUG。2,2001-节食者知道这种现象太好了：他们切割了卡路里，运动，丢失了一些体重，但在某些时候，他们似乎无法摆脱更多的超重。Now researchers from Columbia University College of Physicians & Surgeons, St. Luke’s-Roosevelt Hospital Center, and the Weill Medical College of Cornell University, in a study of rats, may have some new clues why the plateau effect occurs and what could be done to overcome it. The findings have led to clinical tests in people. The investigators theorized that rats--and humans--may not be able to lose weight after a certain amount of dieting, even with drugs or surgery, such as gastric bypass, because the loss of fat decreases the amount of the hormone leptin in the body. Leptin, a hormone mostly manufactured by fat cells, is present in obese animals (and humans) but as the animal loses fat, levels of the hormone go down. With reduced levels of the leptin, the researchers say, the brain mistakenly thinks the animal needs food and sends signals to the body to slow metabolism down and increase appetite, two conditions that make it harder to fight the battle of the bulge. Prior research has shown that rats with diet-induced obesity and obese humans both have high levels of leptin. Giving more to them is minimally effective. The researchers in this study, therefore, gave obese rats a mixture of the weight-loss drug sibutramine, known commercially as Meridia, and leptin, to see if the two substances together might help the overweight animals lose weight. The addition of leptin, they believed, would trick the brain into thinking that no weight was being lost. “By preventing the decrease in leptin levels that normally occurs with weight loss, we theorized that sibutramine would be able to have a greater weight-loss effect,” says Carol Boozer, D.Sc., assistant professor of nutritional medicine in the Institute of Human Nutrition at Columbia, and lead author of the study. Dr. Boozer is also director of the Energy Metabolism Laboratory in the New York Obesity Research Center at St. Luke’s-Roosevelt Hospital Center. “This study shows that an active system resists weight loss, but that the resistance can be overcome,” says Dr. Louis J. Aronne, clinical associate professor of medicine at Weill Cornell Medical College and senior author on the study. “Hopefully, it will point us towards more successful treatments of obesity.” The investigators compared a group of obese rats getting the weight loss drug and leptin to three other weight-matched groups: one that received only saline; one that received sibutramine alone; and one that received only replacement levels of leptin. They found that the rat group taking sibutramine alone lost more weight than rats that received either leptin or saline. The amount of weight lost on the drug, though, started to plateau after five days. But the rat group given a mixture of sibutramine and leptin shed significantly more weight than the group given sibutramine alone. Rats getting sibutramine and leptin also ate less food and had significantly less body fat. Trials with the drug and leptin are under way to test whether the two together facilitate weight loss in obese people, too. The William R. Berkley, Michael Steinhardt and Isaac Blech Research Fund, and the National Institute of Diabetes and Digestive and Kidney Diseases supported this research. Knoll Pharmaceuticals of Cedar Knolls, N.J., which manufactures Meridia, provided the researchers the drug at no cost for this study. The research results are published in the August issue of the peer-reviewed medical journal Metabolism.

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·本研究的其他研究人员是纽约肥胖研究中心副主任，P＆S，纽约福尼斯研究中心副主任，P＆S，P＆S博士，P＆S教授。中心;罗伯特J.爱，谁是在研究期间人类营养研究所的研究生;在研究期间，在研究所和肥胖研究中心是一位博士后研究所的C. Cha。

·P＆S是两个研究人员的家，他们参与了首先鉴定了瘦素基因的实验：Leibel博士和Yiying Zhang，Ph.D.，分子遗传学部的分子和细胞生物学助理教授，分子遗传学分工。张博士现在研究脂肪细胞中瘦素基因表达的控制。

·肥胖是美国的严重健康威胁。根据疾病控制和预防的中心，自1991年以来，成年人之间的肥胖将在全国范围内增加近60％。

·肥胖定义为具有30或更高的体重指数（这相当于174磅的重量。在5'5“的女人，或202磅。在5'10”男性）中。这些人往往大约30磅或更多的超重。每年的超重和身体不活动占超过300,000人的过早死亡，仅次于与烟草相关的死亡。

·超重使得有人能够制定健康问题，如心脏病，中风，糖尿病，某些类型的癌症，痛风和胆囊疾病。