MadSci Network: General Biology

Re: Metabolism level and life expectancy

Date: Thu Feb 21 11:55:23 2008
Posted By: Gabriel Keith Harris, Assistant Professor, Department of Food Science
Area of science: General Biology
ID: 1203571075.Gb

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

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.


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

University of Washington (2005, November 18). Researchers Find Pathways
Linking Caloric Restriction To Aging Process. ScienceDaily. Retrieved
February 21, 2008, from­

Current Queue | Current Queue for General Biology | General Biology archives

Try the links in the MadSci Library for more information on General Biology.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2006. All rights reserved.