Ah Ha! I Knew It!

Grrrrrrr.......


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How Fat Works

Question: The masses of fat in our bodies are made up of millions of individual cells called adipocytes. There are two differences between fat stores in obese and in lean people. Obese people have a larger total number of fat cells, and their individual fat cells are larger, plumper, fuller of fat. What is it that controls these differences? Is there, perhaps, a hormone that signals fat cells to multiply as we gain weight or to stop multiplying as we shed pounds? Or maybe fat cells are like brain cells, and we acquire a number of them early on that remains constant in adulthood?

New research: The answer to these questions was a complete mystery until the publication in Nature this month of this new research. The answers it provides may result in an entirely new way to promote weight loss or gain. The study depends on finding a way to determine the age of the fat cells that make up fatty tissues. The method is an extremely clever one; the researchers made use of the small amount of radioactive contamination absorbed by people who lived during the era of aboveground nuclear weapons testing, from 1955 until testing was banned in 1963.

Findings: Using their method, the authors of the study showed that by the time we end adolescence, our number of adipocytes has been set. Heavy people begin adulthood with more fat cells, and lighter people with fewer, and the numbers won't change as we age or as we become more obese or leaner. The only thing that does change, if we gain or lose weight, is how plump with fat each cell becomes. Meanwhile, however, even though the total adipocyte number remains constant, the cells themselves don't just sit there getting bigger and smaller. Instead, they constantly turn over. Whether you are heavy or lean, losing weight or gaining it, the same rule applies—every year about 10 percent of your body's fat cells die, and they are replaced by the same number of new ones.

Conclusion: We have no idea yet what controls and regulates the one-for-one turnover rate of fat cells. But if we could find and readjust the control mechanism—for example, setting it to replace an annual loss of 10 percent of fat cells with only 8 percent of new cells—we might find a whole new approach to the treatment of obesity. This research is likely to lead us in that direction.