|MadSci Network: General Biology|
Hi Alex, Great question! This idea, that high metabolic rate is linked to shortened lifespan has generally been accepted, but may not really be true. What I mean by that is that small animals, like mice, have very high metabolic rates and very high heart rates and short (~2 year) lives. Big animals, like elephants and whales have low metabolic rates, low heart rates and long (70 plus years). Humans and some birds (parrots, for example) seem to be an exception to this rule, since they are much smaller than elephants or whales, but have a similar (70+ year) lifespan. As you indicated, food restriction has been shown to extend lifespan in many types of animals, from fish to monkeys, but according to recent papers this is not due to changes in metabolic rate. Some people believe that they can extend their lifespan by restricting calories as well. There is even a group, called the Calorie Restriction Society http://www.calorierestriction.org/Home that promotes this idea. Although it seems that it should work, based on animal data, we really do not know if people that severely restrict their calories will live longer. At this point, it is obvious that being overweight can reduce lifespan, but what some people may not realize is that being UNDERWEIGHT can also reduce lifespan. The reason is that if an underweight person has a severe injury or disease, they may not have the resources to heal or to fight off the disease. In my opinion, there is not enough scientific information to say that severe calorie restriction extends life in humans. Based on my understanding of science, SLIGHT calorie restriction (for those of us who are overweight), combined with good nutrition and exercise seems like the best advice for the majority of humans to live as long as possible. Like many things in science, we need more information before we can be really sure. I hope that this helps. References http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6J-4C1K80X-7&_user=290868&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000015398&_version=1&_urlVersion=0&_userid=290868&md5=378e25bac23817e7a51522f535cfb4b4 Harvard Medical School (2003, May 8). Gene That Extends Lifespan In Yeast Points To Paradigm Shift In Longevity Research; May Explain Life Extension Via Calorie Restriction. ScienceDaily. Retrieved February 21, 2008, from http://www.sciencedaily.com /releases/2003/05/030508080253.htm University of Washington (2005, November 18). Researchers Find Pathways Linking Caloric Restriction To Aging Process. ScienceDaily. Retrieved February 21, 2008, from http://www.sciencedaily.com /releases/2005/11/051117180504.htm
Try the links in the MadSci Library for more information on General Biology.