so we know that fat doesn’t make us fat, though if we consume more fat in a day than we need, what happens to that fat? Does it go out with the garbage, does it get stored?
So what happens to the extra fat?
BillJay
#3
If you’re not gaining weight it’s getting burned as energy and one of the ways the body does that without you increasing activity is through thermogenesis where it is just extra “heat” generated by your body. This is also why when undereating, the first obvious sign is feeling cold.
It’s my understanding that at least one way our body unties the energy it generates from the energy used by activity is through an uncoupling protein that acts in the mitochondria that essentially allows it to run wild to convert energy substrates into energy.
bokkiedog
(Nick)
#4
Additional fat could have several fates. It could be used to build structure: cell walls, myelin sheathes etc, it could generate additional heat, it could be excreted (not pleasant!) or it could be shunted into the adipocyte, and thus you’d be temporarily plumper;
HOWEVER, once your metabolism is working properly, so that you can burn FFAs and ketones, and your brain sees the leptin signals from the stored fat and regulates your appetite appropriately, asking “what does your body do with all the extra fat you eat” makes as much sense as asking “what does your body do with all the extra breaths you take”.
“WHAT extra breaths?”, you’d ask, “I breathe as much as I need, and if I breathe too little, I start panting, and if I breathe too much, I get dizzy! The only time I have to worry consciously about my breaths is if I’m ill and my automated systems aren’t working properly”
Ah ha!
Furthermore, a sugar burner needs to worry about their fat-cells because constant insulinaemia renders those cells a Long Term Savings Deposit Account their body-bank never lets them access for withdrawal. So every new addition stays put for a long time - if not forever.
But if you’re a keto-adapted fat burner, your fat cells are like a rapid access checking/current account. It might get an unusually generous deposit one day, but the next day that’ll be just as easily spent, with no angry pancreatic bank-teller or accountant wagging their bossy finger at you 
So, in summary: if you’re metabolically healthy and eat a bit more fat than you need in one day, it’ll be used for repairs, and the rest stored temporarily. Your appetite or energy expenditure would then react appropriately over the next day so that the metabolic maths balances, so to speak. Anyone who’s feasted on a huge steak one day and can barely face any food the next day understands this intuitively.
richard
(Richard Morris)
#6
Some does. You have a maximum rate at which you can break down fat in the gut, drag it into enterocytes, and package it into giant lipoproteins. All the rest goes out the garbage.
Did you ever see those ads for chips that were cooked in the low-fat fat called olestra? May cause anal leakage. That’s what is happening there. Fat in the stool doesn’t behave well … I tend to think people who overeat fat soon stop.
But let’s say you overeat fat and for the sake of argument you digest all of it, what happens.
Well first of all you end up with a LOT of energy in circulation, in those big lipoproteins (chylomicrons). They are only made when you eat fat, and you body knows that’s high energy, so the presence of chylomicrons will depress your appetite until they can all deliver their contents and be cleared by your liver. So first thing that happens is you likely stop eating.
Next thing that happens is you body starts doing things on it’s list of “Things we’re going to do next time there is plenty of energy”. Your body will also run fractionally hotter as brown fat takes up excess energy and turns it into heat. I’m not sure anyone knows why it does this, but in overfeeding studies it seems to always happen.
I have a theory related to the fact the only other time the body runs hot is when it’s fighting off an high grade infection. It also dumps glucose into circulation at that time because our immune system runs more efficiently at a slightly hotter temp with abundant glucose. My theory is we use take advantage of the temporary glut to purge low grade infections, and run our immune system more efficiently.
The next thing that happens is we get crazy legs, and other involuntary consumption of energy. If we can do exercise we will.
In overfeeding experiments, volunteer prisoners were given increasingly more food and had their exercise limited, and their metabolic rates jumped from around 2000 kCal.day to over 8,000 kCal/day. They also of course gained weight, they also all ran at a hotter temperature. They were prevented from exercising more than 1 hours a day, but at 8,000 kCal/day they were burning a lot of calories.
What happened when they stopped the experiment was they rapidly lost all the weight they had gained because their total daily Energy expenditure (TDEE) was 4x normal, and then as they got closer to their starting weight their TDEE dropped back to the normal level.
bokkiedog
(Nick)
#8
And this is why things like doughnuts represent something uniquely awful. You have the sugar and flour keeping you glycaemic and then insulinaemic.
The insulinaemia means you can’t burn the fat from the oil in the doughnut, so it all gets shunted into your adipocytes.
And then, for a couple of hours, you’re in storage mode, and then you have your hypoglycaemic crash, because your brain last knew what to do with ketones when you were at your mother’s breast. So perhaps you have another doughnut. More sugar. More insulin. And another bolus of fat on a one-way trip to your fat cells
With all this sugar to burn - and convert - your body doesn’t have a chance to begin thinking about burning fat. And you’re now well on the sugar rollercoaster. Let’s say you have a boiled sweet. No fat. But the insulin and the sugar means that the fat you dumped into your adpiocytes has no chance of escape.
What’s worse is that the constant insulinaemia causes your brain increasingly to ignore the leptin signals from the fat in your body. “HEY, BRAIN, BURN US ALREADY!”
“What’s that strange muffled sound from my big belly”, thinks the brain, “Who knows? Anyway, gimme more sugar. Maybe another doughnut”
And eventually, the sugar burner tries in desperation to starve themselves, and not to eat any fat so their adipocytes don’t keep getting new unburnable loads thereof. But still, the glucose keeps coming, and the insulin keeps screaming “Store! Store! Store!” - and now, without dietary fat, the poor dieter can’t absorb the vitamins from their mounds of soggy steamed broccoli.
And thus continues the metabolic tragedy of the sugary, oily doughnut eater.
farmgirl
(Arlene)
#9
Wow, wonderful explanation. Many of us try to over-think this way of eating, and certainly some of us are at a place where we have to give our bodies a little help to become “normal” again. Yet, I like your way of thinking. Eat right and let the amazingly wise body take care of the rest.
bokkiedog
(Nick)
#10
Exactly! And the calories-in-calories-out response to that is like people who have asthma or hyperventilation syndrome being told “just make sure you take enough breaths in vs breaths out!” as if they’re being helpful.
Your body has to be helped off the metabolic rollercoaster, has to be re-taught to listen to its endocrine signalling, and to be able to burn the fuel it evolved to use best. This takes time, and having people tell you you’re just glutinous or lazy in the interim is, I’m sure, no help!