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Saturated Fat
Felines get most calories from protein, cats choose a diet that contains about 35% of calories from fat (which translates to eating the organs and flesh of lean animals), other species will differ. Give a hungry cat a fatty steak and watch it turn its nose up at the chunks that are pure fat.
Ketones are not the preferred fuel for most cells. They are more efficient and muscle sparing than relying solely on gluconeogenesis during starvation. Despite this, gluconeogenesis still occurs during ketosis, some cells cannot use ketones.
You haven't refuted what I've said so far. You're repeating a flawed narrative that is only accepted in low carb circles. Glucose is our preferred source of energy. Homo Sapiens can actually be distinguished by our reliance on starch which is a much better source of it than protein. Neanderthals appear to have been mostly carnivorous and lacked amylase. They may have had gluconeogenesis abilities similar to carnivores. Homo Sapiens do not. Inuit have actually made adaptations that improve their gluconeogenesis. While some may be more equipped than others for gluconeogenesis (we have some Neanderthal DNA) most are built for starch consumption.
Paleolithic humans were smart and were always planning ahead, storing and preserving food. Grains and legumes were exploited as an excellent food, starch that can be easily stored.
Quote from Judy on January 25, 2022, 5:43 pmWe are equipped for survival. We eat carbs when they are available because it provokes insulin, which puts it into storage in the fat cells where it can be used when the carbs (fruit and plant foods) are gone. The body tries hard to protect its precious fat stores because that is its emergency stash, therefore the carbs get burned until they are gone and then it switches to burning fat. We now live in an endless summer with abundant food and we never need to use up our reserve energy. Clearly a recipe for obesity. Ketones from saturated fat gives us a way to game the system by satisfying our hunger without making us fat.
Salt: why do you think ketosis is not a preferred state? It takes a few more calories to use gluconeogenesis to make the small amount of necessary glucose, but when has burning a few more calories ever been a negative?
" We eat carbs when they are available because it provokes insulin, which puts it into storage in the fat cells where it can be used when the carbs (fruit and plant foods) are gone."
What?? The body will not turn glucose into fats if the muscle/liver glycogen is not full and if you re not in calorie surplus. This glucose will be stored as glycogen and used as energy.
"We now live in an endless summer with abundant food and we never need to use up our reserve energy. Clearly a recipe for obesity. "
That's why you need some self discipline and eat only the amount of carbs that you need. But even then obese people will get fat from stored dietary fats. Carbs are burned as energy and excess via thermogenesis.
" Ketones from saturated fat gives us a way to game the system by satisfying our hunger without making us fat. "
This is not true at all. Storing dietary fats as body fat is super easy for the body so if you are in calorie surplus on keto diet you will gain weight. The reason why people lose weight on keto is because it shuts down appetite. SO it is hard to eat excess of calories on keto. Same with low fat high carb diets. It's very hard to eat excess of calories with just carbs/protein.. but the reason why people on mixed diets get fat is simple. It's very easy to eat excess of calories on diet that is high in sugar and fats. But again the fat is stored as body fat. Carbs are used for energy.. Also you need to realize that people back in the day were in ketosis because they were starving not because they were eating huge amounts of dietary fats. Like Tim says you really think that eating butter, oils, bacon, nut butters etc. is natural diet? In which world exactly? The only source of fats in the wild are wild animals and they are extremely lean...
So to sum this up keto to me is for inactive people(who will not use the glycogen in the muscles) and who have no self control. So they easily overeat.. If that is the case shutting down appetite with keto is maybe a good thing. But for active people glucose always will be the best source of energy for them.
Quote from tim on January 25, 2022, 8:39 pmFelines get most calories from protein, cats choose a diet that contains about 35% of calories from fat (which translates to eating the organs and flesh of lean animals), other species will differ. Give a hungry cat a fatty steak and watch it turn its nose up at the chunks that are pure fat.
Ketones are not the preferred fuel for most cells. They are more efficient and muscle sparing than relying solely on gluconeogenesis during starvation. Despite this, gluconeogenesis still occurs during ketosis, some cells cannot use ketones.
You haven't refuted what I've said so far. You're repeating a flawed narrative that is only accepted in low carb circles. Glucose is our preferred source of energy. Homo Sapiens can actually be distinguished by our reliance on starch which is a much better source of it than protein. Neanderthals appear to have been mostly carnivorous and lacked amylase. They may have had gluconeogenesis abilities similar to carnivores. Homo Sapiens do not. Inuit have actually made adaptations that improve their gluconeogenesis. While some may be more equipped than others for gluconeogenesis (we have some Neanderthal DNA) most are built for starch consumption.
Paleolithic humans were smart and were always planning ahead, storing and preserving food. Grains and legumes were exploited as an excellent food, starch that can be easily stored.
Ketones are preferentially burned, in the brain cells that are capable of burning them.
That's not true. In glycolysis, the brain runs on glucose. In well established ketosis, ketones can supply about 60% of the brain's energy needs. It takes time for the brain to switch to ketones in ketosis so ketones are certainly not the brain's preferred fuel in glycolysis.
Quote from tim on January 26, 2022, 8:10 amThat's not true. In glycolysis, the brain runs on glucose. In well established ketosis, ketones can supply about 60% of the brain's energy needs. It takes time for the brain to switch to ketones in ketosis so ketones are certainly not the brain's preferred fuel in glycolysis.
I'm not talking about ketosis, you're getting hung up on ketosis. Cells will preferentially burn ketones when available, this is a fact. That's all I mean by preferred fuel, in the presence of glucose and ketones the cells will burn ketones first and then when they are gone, burn glucose, and when the glucose is gone, for those cells who are able to, then burn fat.
You're quoting me talking about glycolysis while accusing me of getting hung up on ketosis... What I said is super clear and factual.
Brain cells do not burn ketones first. As I said above, in glycolysis the brain runs on glucose. Brain cells do not use ketones before glucose.
Quote from tim on January 26, 2022, 11:25 amYou're quoting me talking about glycolysis while accusing me of getting hung up on ketosis... What I said is super clear and factual.
Brain cells do not burn ketones first. As I said above, in glycolysis the brain runs on glucose. Brain cells do not use ketones before glucose.
Wrong.
Reply to Jiri: "Wild animals are extremely lean." Some, like rabbits, are lean; you will die in about 3 weeks if you try to live on nothing but rabbit due to what the Inuit called "rabbit fever." Seals, whales, cold water fish, geese, ducks, etc. are very fatty. (A bear's belly drags the ground when it is ready to hibernate.) Other animals are fatter during times of plenty, leaner during winter or famine.
Also, "What?? The body will not turn glucose into fats if the muscle/liver glycogen is not full and if you re not in calorie surplus. This glucose will be stored as glycogen and used as energy." Yes, glucose will be stored as glycogen, but we can only store about 2,000 calories in reserve as glycogen. That is why marathon runners do better on a ketogenic diet. A runner using carbs for energy will "bonk" or hit the wall after the glycogen is used up and must get refueled with "energy drinks" on route to keep going. One using ketones can run until they have depleted all their body fat, which is not likely to happen.
One more comment before I move on the other things:
Another advantage of eating a low-carb/ketogeic diet is that you don't need to breathe as much. The Navy Seals are putting their divers on Keto so they can stay underwater longer. The reason the diet helps is because it produces fewer waste products that they have to get rid of. I witnessed this first hand when my husband had a cardiac arrest from low Potassium caused by blood pressure medicine. I called 911 but the team from the closest fire station was already out on a call and it took a long time for anyone to come. They say we can live for 5 minutes without air, but it was at least twice that long, maybe more; they told me they didn't want to get my hopes up because it was "bad, very bad." They tried for an hour or more to get his heart started before giving up and putting him in the ambulance. The cardiologist said most patients who came in like he did, just died, "but sometimes we get a miracle." They gave him a 1% chance of surviving in any condition.
He was in the hospital for 11 days but not only survived, but survived with no damage. The nurses were calling him "Superman" among themselves. He wasn't a superman; he was on a low-carb diet. The whole story is here: https://www.carbwarscookbooks.com/the-worst-day-of-my-life-and-an-important-warning/
I'm not wrong. This is elementary physiology.
The mammalian brain depends on glucose as its main source of energy. In the adult brain, neurons have the highest energy demand [1], requiring continuous delivery of glucose from blood. In humans, the brain accounts for ~2% of the body weight, but it consumes ~20% of glucose-derived energy making it the main consumer of glucose (~5.6 mg glucose per 100 g human brain tissue per minute [2]).
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/
Glucose is the only fuel normally used by brain cells. Because neurons cannot store glucose, they depend on the bloodstream to deliver a constant supply of this fuel. Fatty acids do not serve as fuel for the brain, because they are bound to albumin in plasma and so do not traverse the blood-brain barrier. In starvation, ketone bodies generated by the liver partly replace glucose as fuel for the brain. (Biochemistry. 5th edition.Berg JM, Tymoczko JL, Stryer L.)
https://biology.stackexchange.com/questions/34159/why-is-the-brain-dependent-on-glucose
Glucose, a form of sugar, is the primary source of energy for every cell in the body. Because the brain is so rich in nerve cells, or neurons, it is the most energy-demanding organ, using one-half of all the sugar energy in the body.
Brain functions such as thinking, memory, and learning are closely linked to glucose levels and how efficiently the brain uses this fuel source. If there isn’t enough glucose in the brain, for example, neurotransmitters, the brain’s chemical messengers, are not produced and communication between neurons breaks down. In addition, hypoglycemia, a common complication of diabetes caused by low glucose levels in the blood, can lead to loss of energy for brain function and is linked to poor attention and cognitive function.
“The brain is dependent on sugar as its main fuel,” says Vera Novak, MD, PhD, an HMS associate professor of medicine at Beth Israel Deaconess Medical Center. “It cannot be without it.”
https://hms.harvard.edu/news-events/publications-archive/brain/sugar-brain