X-Message-Number: 25062
Date: Tue, 16 Nov 2004 17:58:38 -0800 (PST)
From: Doug Skrecky <>
Subject: CR no benefit on housefly longevity

FASEB J. 2004 Oct;18(13):1591-3. Epub 2004 Aug 19
Effect of caloric restriction on life span of the housefly, Musca domestica.
  Caloric restriction (CR) has been found to extend the life spans of a
wide variety of species, transcending phylogenetic boundaries. The
objective of this study was to test the generality of this phenomenon,
using the male housefly as an insect model in which food intake can be
quantified precisely. Sucrose was found to promote a longer life span than
diets additionally containing proteins and lipids. Flies were fed sucrose
or a more complex diet ad libitum (AL), or in amounts ranging from 50% to
100% of the average amount consumed by young flies. CR shortened rather
than prolonged the life span of houseflies, particularly flies fed sucrose
only. The rate of oxygen consumption was not affected by caloric
restriction or by the exclusion of proteins and lipids from the diet, and
the reproductive activity of male flies remained unchanged by sucrose
feeding. Thus, it is unlikely that the life-shortening effects of CR can
be explained either in terms of an adaptive response in metabolic rate or
use of a suboptimal food source. Results of this study contradict the
widely held view that CR has a life-extending effect in all species.

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