That's kind of what I'm asking. I've heard they are used immediately, but also hear they must go through a cycle in the liver to get converted into a form the body can use.
Originally Posted by j3nn
So, let's say we drink a cup of melted coconut oil or melted butter. It hits the stomach and probably pretty quickly gets in the small intestine where it begins to be absorbed into the bloodstream. Are these fat molecules able to be incorporated in the cells for use in ATP production? Or do they require a trip through the liver to get converted, then stored in fat tissue.
Some places I've read say the only fat that can be used for ATP or energy production at the cellular level is lipids, or free fatty acids, which are release from our adipose tissue.
Other places act like fat you eat gets used directly for energy and if there's a surplus it gets stored in adipose tissue.
serious answer - yes. polar explorers thing - what's not burned is stored; only so much can hang out in blood stream (albeit more than glucose). what's the mystery you're trying to unravel?
Originally Posted by otzi
My understanding is that fat is shuttled to fat cells FIRST. The FFAs in the blood are released from storage. So I don't think that fat is burned directly, without being stored first.
Just trying to separate fact from bro-science. I had always believed that all dietary fat was stored or converted to something else, then burned. I have recently been hearing that dietary fat is burned directly by cells. If it is burned directly, it makes eating lard a reasonable thing to do if you need instant energy, like a polar explorer or free diver in cold water, but if it's all converted first, it doesn't make much sense. Seems like just loading up on any food would be enough.
Originally Posted by jakey
edit to add: Just got this from wikipedia:
"Fats also serve as energy stores for the body, containing about 37.8 kilojoules (9 calories) per gram of fat. They are broken down in the body to release glycerol and free fatty acids. The glycerol can be converted to glucose by the liver and thus used as a source of energy."
So, if dietary fat has to be converted to glycerol, how is it burned directly?
Last edited by otzi; 11-30-2012 at 03:06 PM.
wait sorry, some of this is just how we're defining terms like "storage," and now i see what you're getting at. most things have to be converted at some point, in your body (even glucose). whether the site of conversion is the small intestine (short chain fatty acids), the liver (medium chain), or the adipocyte (triglycerides back into fatty acids), i still don't consider that to mean 'storage.' even with elevated insulin, your adipocyte is constantly releasing FFAs and your liver is constantly repackaging them as triglycerides. sort of like amino acids, in muscles, it doesn't really stop.
Originally Posted by otzi
also dietary fat does not need to be converted to glycerol, your mitochondria love FFA.
good discusion! been wondering the same
i just finished up one month of using coconut oil and coconut butter as my fat source. Was not the best source of fat for Me.
my jeans are tight now and this was the only thing i changed - what fat i used. For some people it helps them with energy, i should have stopped using it when i noticed it did not do that for me. It sure does taste amazing though!
The difference between olive oil and coconut oil is that olive oil is a long chain fatty acid and coconut oil is a medium chain fatty acid which can be burned more quickly.
Originally Posted by emmie
It depends on how "instant" you need the energy though. So even if high fat foods such as pemmican is an excellent source for energy in a cold climate, and to be preferred on a polar expedition, why does not marathon skiers and others use it when competing in cold climates then? Because fat is “low octane”, it doesn’t burn fast enough and it also takes longer time to digest and get into the system than a lukewarm sugar drink when doing high intensity work...
Originally Posted by otzi
That's kind of the conclusion I came up with as well. I guess to illustrate my point that you don't 'burn ingested fat directly' you'd have to color-code or irradiate a stick of butter and follow that through your body with an MRI or PET scan. My thought is that if you eat pure fat (CO, Ghee, lard, Crisco, etc...) none of it gets picked up by any mitochondria for energy purposes, but rather gets processed by various means and stored in adipose tissue for later release as free fatty acids that the mitochondria can use.
Originally Posted by Gorbag
So, eating a stick of butter (for instance) provides a source of fat calories to keep your adipose tissues filled, but the butter will not be burned preferentially over free fatty acids because the CAN'T be burned directly.
So probably the only people who would need to eat a stick of butter or hunks of lard are people who are undergoing extreme physical exertion such as those on a polar expedition, mountain climbers, distance swimmers in cold water...