Fat as emergency storage

Question
Todd
When calories in exceeds calories out, the body stores the excess as fat. We are taught that this is nature's way of insuring us for times when food is scarce. While this seems to work for hibernating bears, it doesn't for humans; when people starve, at least initially, they loose MUSCLE, not fat.
What's going on?
DBRJ

Answer
DBRJ,

The idea that people will lose lean muscle, initally, when on a "starvation" diet cannot be considered accurate.

The loss of lean muscle vs. fat seems to be pre-determined by body compsition (% body fat) when starvation starts.  People with a lower % body fat may lose more fat, relative to muscle, initially and people with higher body fat may lose more muscle, relative to fat, initially.  People with higher body fat will also tend to have more muscle than thin people.

One theory is that the rate of muscle and fat utilization will be "that muscle and fat run out at the same time so as to maximize survival time".

Experiments with starvation are not popular, as you can guess.  One such study was done by the University of Minnesota (Keys et al., 1950).  Below are some links to information mainly based on this study.

http://river-centre.org/StarvSympt.html

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

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

http://www.merck.com/mrkshared/mmanual/section1/chapter2/2b.jsp

There are no simple answers to explain WHAT happens during starvation or WHY things happen during starvation.  Suffice to say that starvation and "starvation diets" are serious business not to be taken lightly.

Best wishes.

Todd

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