CR compensation?

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Hi All,

This not pdf-available paper shown excerpted for the abstract below seems to

present

what may be unexpected results. Fat mass was unaffected by CR? Compensation

for CR

was mainly via reduced activity? Why was not the body fat level of the MF1 mice

reduced by CR? Is the answer:

.... Mice (MF1/DBA) heterozygous for the IGF-I knockout allele ...?

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=pubmed & dopt=Abstra\

ct & list_uids=15930167 & query_hl=7

Hambly C, Speakman JR.

Contribution of different mechanisms to compensation for energy restriction in

the

mouse.

Obes Res. 2005 Sep;13(9):1548-57.

PMID: 16222057

OBJECTIVE: Restriction of energy intake produces weight loss, but the rate of

loss

is seldom sustained. This is presumed to be a consequence of compensatory

reductions

in energy expenditure, although the exact contributions of different components

to

the energy budget remain uncertain. ... 20% dietary restriction. ... 50 MF1

mice.

Forty mice were then placed on a restricted diet at 80% of their ad libitum

intake

for 50 days. The remaining 10 mice continued to feed ad libitum. ... RESULTS:

....

During the restriction period, body mass increased in both the control and

restricted groups, but at a slower rate in the restricted mice. The control

group

increased in both fat and fat free mass; however, although the restricted group

increased fat to the same extent as the controls, fat free mass increased to a

lesser extent. The contributions of the different components of the expended

energy

to compensate for the reduced energy intake were energy deposition, 2.2%;

resting

metabolic rate, 22.3%; and activity, 75.5%. DISCUSSION: Mice were able to

compensate

almost completely for the restricted energy intake that was achieved by altering

the

amount of energy required for each component of the energy budget except

digestive efficiency.

Al Pater, PhD; email: old542000@...

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