We still hear otherwise sensible medical, nutritional and 
fitness people urging us to avoid fats or eat less fat.

This seems to imply that people's appetites are geared 
to want a certain fixed volume of food; but we all know 
that appetite and satiation is far more complex than that.

The digestion of fat is a complex process and I have come
to the sad conclusion that you'd really need to be a lipid 
physiologist to understand the process well. So I have 
a question:

"Where fat is deposited in adipose tissue, is the fat that 
is eaten, the same fat that is deposited? Or has it been 
broken down from fats into constituents and recombined 
for deposition?"

To illustrate: if I eat a food with a particular saturated fat 
(say palmitic acid or lauric acid), does the fat stay in that 
form as the body processes it? Or is it broken down into 
other fatty acids or other simpler components and, in some 
cases, recombined into a new fatty acid?

A second illustration: we encourage a consumption of 
omega-3 fatty acids at a rate above that in the standard 
diet. But are the omega-3 fats we eat destined only for 
(a) deposition in their original omega-3 form, 
(b) consumption by our bodies in their original omega-3 form
(c) burned as energy, or 
(d) excreted unaltered? 
I think we know (particularly from Barry Sears' work) 
that omega-3s have significant health benefits when 
they are synthesized into eicosanoids and interact with 
enzymes.

So, I can guess the answer to my question, but I'd like 
some reference, preferably one with an explanation even a 
'liberal arts graduate' can understand. We know that the 
body can create fat out of carbohydrates or surplus protein, 
so presumably it similarly transforms the fats eaten into 
the fats it wants. Perhaps only some fats are 
transformed in the process of digestion - I'd like to know.

If my feeling is right, this gives us another way of 
demonstrating what we all know: that eating fat need not 
make a person fat or even be deposited as fat. 

Keith