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Weight Gain May Not Be Based Just on What You Eat
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Page: << Prev | 1 | 2 | 3 | Next >> Also, the worms' feeding behavior appeared to be dependent on their nervous system's shifting gauge -- both genetically and environmentally triggered -- as to how much food was available for consumption. When food was scarce, fat reserves piled up as the worms' metabolic rate adjusted to conserve energy and save fat for a rainy day.
Comparisons to humans are obviously limited by appreciable systemic differences. For example, the authors noted that high levels of serotonin appear to lead to fat loss in the worms, as is the case with humans. But, while in worms, serotonin boosts lead to increased eating and fat loss, in humans, serotonin bumps are known to prompt less eating, which in turn leads to a decrease in fat tissue.
Nevertheless, Ashrafi and his team concluded that their analysis of worms offers clear cross-species indications that whether one is fat or thin is not a pure calculation of caloric intake but rather a complex result of multiple nervous system calculations based on both genetic and environmental factors.
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"We don't know the real answer yet," Ashrafi said. "We are just beginning to scratch the surface. But I think chances are pretty good that this is something likely to be operating in most organisms. And, the fact is that the consumption of food is a very dynamic process, with a strong genetic component that clearly goes beyond the question of diet."
Alice H. Lichtenstein, director of the Cardiovascular Nutrition Lab at Tufts University's USDA Human Nutrition Research Center in Boston, cautioned that attributing weight and fat gain to environmental or genetic sources can be tricky and complicated.
"We clearly know that the nervous system will impact on food intake, and the exploration of genetic predispositions toward weight gain and obesity is not new," she said. "In fact, there has been an immense amount of effort over a long period of time devoted toward sorting this out."
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Copyright © 2008 ScoutNews, LLC. All rights reserved.
Last updated 6/5/2008
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SOURCES: Kaveh Ashrafi, Ph.D., assistant professor, department of physiology and Diabetes Center, University of California, San Francisco; Alice H. Lichtenstein, D.Sc., director, Cardiovascular Nutrition Lab, Gershoff Professor of Nutrition, USDA Human Nutrition Research Center, Tufts University, Boston, and immediate past chair, nutrition committee, American Heart Association; June 2008, Cell Metabolism
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