This is where I was trying to go on the subject, and what I’m trying to understand more. Thanks.
@Emacfarland This is really interesting. I definitely feel this, though don’t really know if that’s what’s happening.
I will say, based on personal experience, that if I am not eating enough and I stay very active, I will become quite catabolic and I know my body will start breaking down muscle.
I don’t think I’m a hyper-responder, as I’ve never had an elevated cholesterol count (though I don’t really keep track). With this thread I’m trying to figure out both why I feel bad after exercising & fasting or how to supplement (with carbs or fat) to avoid this.
I’ve had experiences where I collapsed after significant energy expenditure (just from walking all day on an extended fast) and 4g of carbs immediately restored me to normal.
@nickdag, the type of activity will also determine what fuel your body will primarily use to fuel it- exercising in lower heart rate zones (or what we would call endurance or cardiovascular exercise) will utilize mostly fat, even in those that eat a mixed diet and are not fat adapted. Anaerobic activity, or short, intense bursts of exercise are more glycolytic, still using some fat but most glucose as fuel. If you’re fasting and walking a lot you’re using most fat. Assuming you get enough sodium, potassium and magnesium, you’ve been fat adapted for a while, and you ate well before your fast, you probably feed cruddy and sluggish because you’re pushing past a point, either through how long you fast or the activity you’re doing or both, where your body can sufficiently provide enough energy. So you can maybe add some fat if you want to keep fasting or ease up on your exercise
This has been completely debunked. The 31.5 kcal/day/lb fat is complete nonsense. Phinney, Volek, and Noakes published a really interesting article where they compared the fat burning of competitive ultraendurance athletes, half of whom were “carb burners” and half of whom were LCHF. The LCHF athletes had an mean bodyfat % of 9.6%, and the carb burners had mean bodyfat of 7.8%. They are basically among the leanest, fittest men walking the earth.
Unsurprisingly, it turns out that LCHF athletes can metabolize fat at a staggering rate. It’s off the charts. It’s almost as if they became fat adapted!
Think about it for a minute. If a man weighs 140lbs, and is 10% bodyfat, that means he has 14lbs of fat. Using the 30kcal/day/lb bodyfat, that would mean he would be able to get 420kcal/day from his fat stores at a maximum.
These guys run a marathon in the fasted state as a “light warmup”. The 30kcal number is laughable.
I’m not suggesting that the rest of us are identical to these guys, they’re ironman winners after-all, but it is pretty compelling evidence that the metabolism can be trained to burn fat differently than your average SAD couch potato.
Yeah, that’s one of (many, honestly) accepted ‘facts’ that people are way too eager to grab onto. So what was done there is that the scientist took the data on lean mass and fat mass from the Minnesota Starvation Study and mathed it.
And that’s it.
So he (indirectly) looked at 36 white males from seventy years ago and derived an absolute limit for all humanity.
(To be fair, the paper’s author isn’t necessarily doing that - people interpreting it are)
And, more relevant to the forum, these guys were eating a mostly carb based diet. So assuming it’s an absolute limit in humans eating differently is pretty dubious.
Even IF you assume the Minnesota Starvation Study was able to track body composition precisely enough for the initial numbers to be right (which I am suspicious of - we can’t actually do that well NOW) and that the circumstances of the study apply to everyone…
The number is wrong. The paper’s author himself has said the actual number is 22(ish) calories per pound, because the initial number assumed perfect energy transfer.
But that hasn’t made it into the popular keto consciousness.
Yup. I read the study where the 30kcal/day number comes from. It was just meant to be a WAG “wild ass guess”, but somehow it became gospel.
@Don_Q Thank you for the study link. We’ve still got so much to learn! Evolutionarily it makes sense. In the conditions of the last 2.5 million years of the Pleistocene, if our hunter ancestors had to refuel and refeed on carbs to keep up we would not be here.
Yeah, the assumed level of precision there is a little bonkers (31 POINT 5? Really?).
If it were quoted as 31 +/- 15 or something I would trust it more.
Related pet peeve: when people quote their macros down to the fraction of a gram or their energy in fractions of a calorie. Did you really have exactly 2071.6 calories yesterday? Do you know that for certain?
Oh, I think that they absolutely did refuel and refeed and refuel on carbs, it’s a question of frequency!
I think if they came across a carb source like a wild raspberry patch in the fall, they didn’t leave until everything was gone. That’s how bears behave even now. That season was brief though. My guess is that this is why we have the reaction to carbs that we do, and why it’s so addictive.
It’s a good ice-age survival strategy. The folks that got big dopamine hits eating sugar/carbs and just stayed in the berry patch for a week got fat enough to survive the winter and pass they’re genes down. Those that ate a few berries and kept walking in search of antelope died before spring. I suspect carb addiction kept the human race alive in the non equatorial climates, and may well have been what inspired agriculture in the first place (I’m tired of goat, I want some fried potatoes, and I want them now!).
That’s total non-scientific conjecture on my part, but it kind of makes sense…
The macros thing kind of relates to why (I believe) people like things like the ‘31.5’ get taken up - people do not like uncertainty.
Not a profound insight, but in keto as in life there’s a lot of stuff that’s…truish, basically. ‘Insulin prevents fat loss’ for instance, isn’t really true, but it’s useful shorthand most of the time. But people grab onto that, because they want to Know. Capital k know.
It’s the same deal as worry about your macros - say you want to eat a gram of protein per pound of lean mass. People mostly ignore that…
You don’t know your lean mass that precisely. Not even with DEXA
You don’t know the exact protein in what you’re eating. Not even protein powder.
Even more abstractly, it treats all protein as the same.
That’s not to say these rules are wrong, just not to stress too much about the precision. Trying to get to one gram per pound or whatever is fine, but if you get 163 or 167 well, remember your numbers aren’t really right to begin with. Good enough is good enough.
Which, this includes me, literally today I had to remind myself that TODAY.
The moment I think I know something with exactness, I look at the plot of my total body weight over time. The measurements (red) bounce all over the place in response to hydration, eating, elimination, and so forth. Even though I weigh myself in underwear in exactly the same spot at the same time of day. I’d like to know things with more precision but I know I can’t.
No doubt anything edible was consumed when discovered, including leftovers from another animal’s kill. Our ancestors scavenged as much as they hunted. What many of us forget, however, is that during the glacial maxima of the Pleistocene the available flora was very different from what it is now. Even in the tropics and subtropics which were glaciated only at high elevations, the overall temps were lower and edible flora very different. Consider this.
I lived for the better part of a decade at Lake Laberge, Yukon. This is a ‘sub-arctic’ climatic region that I suspect resembles the subtropics during glacial max. Short, warm summers and long very cold winters.
During the summer berries of various descriptions grow quite extensively. Unfortunately for humans, the most prolific are not particularly edible: a bushy shrub known as ‘buck brush’ that produces a small red berry called ‘bear berry’, and a ground hugging cover plant known as ‘kinnikinick’ that also produces a small red berry. Both these berries are high in cellulose and very low in digestible carbs. Bears and ruminants with the guts to digest cellulose eat these berries and put on fat. But they’re useless to humans, even assuming you get past the bitter, pasty taste.
Strawberries and blueberries also grow extensively in specific locations. But these edible berries are very much smaller than what we know now as strawberries and blueberries. We called our homestead ‘Strawberry Fields’, not only from the Beatles’ song, but because wild strawberries grew in the open fields surrounding our property. The strawberry plants only produced berries in years when very specific conditions of rain and temperature occurred on just the exact timing of the late spring. These conditions only occurred every 2-3 years, never in succession. Even in years of abundance, these strawberries were so small that the time and energy required to pick enough for a meal were far away more than the energy got from eating them.
So I don’t think our Pleistocene ancestors derived more than a pittance of nutrients from plants. There was no ‘fattening up’ for the winter eating carbs. They just weren’t on the menu until the agricultural revolution began the human love affair with plant-based carbs. In my opinion.
It is not only sugar
Metabolic Flexibility - Get Real
Nice! I’m a northern Alberta survivor myself (Ft. McMurray). I like it better down south in New York where it’s nice and warm…
That very well could be the case. I don’t think anyone knows for sure. I suspect that the human dopamine response to sugar and carbs, and consequent carb addiction was an evolutionary adaptation, but even that’s a guess. How it arose is another question altogether…
Been there, too! Very similar climate, but probably hotter in the summer and colder in the winter, since LaBerge is close enough to the Pacific Ocean to be somewhat moderated. The St Elias mountains are quite a good barrier, but a lot of moist, warm air makes it over into southern Yukon.
I think all carb related metabolic capabilities in humans are ‘metabolic relics’ of our primate ancestry. We evolved from tropical herbivores. It is interesting to note that of all primates, only humans have been able to escape the tropics and colonize virtually every place on the planet. All of our primate relatives are still trapped in the tropics. Humans gave up the big guts necessary to digest cellulose in exchange for a big brain and the necessity to eat more nutrient dense meat and fat to sustain it.
I heard an interview with a member of the Sami people, who followed reindeer. He said in the (short) summer, they would eat berries and tubers if they could, basically to fatten for the winter. Otherwise, they ate reindeer. He explained quite a few techniques they had for fermenting meat and otherwise making the meat last for as long as they could. And they had to deal with emaciated animals in the spring, so had to get fat through other techniques, such as eating the brains, eyes, etc.
The effect of dietary fat on insulin secretion is so small as to be virtually non-existent. It is the glucose in carbohydrate that raises insulin secretion significantly, and on a high-carb diet, protein raises insulin at about half the rate of glucose. On a low-carbohydrate diet, the effect of protein on insulin secretion is compensated for by an equivalent rise in glucagon, which negates the effect of the insulin. Fat has no effect on insulin under any circumstances.
I should probably mention that we need some insulin circulating in our blood, or we will starve to death (this was the usual fate of Type I diabetics before the discovery of insulin a century ago). This is why we don’t normally worry about the effect of protein on insulin secretion, especially since protein is essential to our diet. But since insulin, among one of its multitude of jobs, is the primary fat-storage hormone, we don’t want the level in our blood to rise so high as to trap fatty acids in our fat cells. Eating as little carbohydrate as possible is what keeps insulin low, and eating in a way that allows insulin levels to drop between meals is another part of the keto eating strategy.
Yes, this is why Dr. Fung recommends that very lean people take some source of fat while fasting. The primary rule of fasting is that if you don’t feel well while fasting, eat.
It’s a nice question, because the figures of 4/4/9 kcal per gram of carb/protein/fat respectively are inaccurate, to begin with. I believe carbohydrate yields just under 4 (k)cals/gram, protein just over, depending on the amino acids in question (not that protein is generally used to fuel energy expenditure anyway, but still), and fats range from 6-point-something to over 10 kcal/gram, depending on which specific fatty acids are under consideration. (Sorry not to be more precise, but I’ve lost the link to that paper.) Remember, too, that food calories are kilocalories, even though we generally leave off the “kilo-” part when talking about foods and their energy content,
ETA: Another complicating factor is that the caloric values of food are determined by burning a measured quantity of the food, to see what amount of heat it gives off. It would be interesting to see just how that number relates to the amount of energy locked up in the phosphate bonds of the molecules of adenosine triphospate produced when the food is metabolised.
Did you even read the studies and look at the charts?
You keep perpetrating the belief that high insulin levels are synonymous with high glucose levels.
There was something weird about the discussion portion of that study…
If you take a quick look through the rest of the study you see that it’s basically giving examples of trials where they showed that omega-6 polyunsaturated fats caused a certain amount of insulin secretion in rats. This wouldn’t have made sense to me a few months ago, but as I learn more about these fats, I’m starting to see the bigger picture. Linoleic acid (of course) seemed to have the most effect on insulin out of the different fats. They also said that this insulin response decreased in rats fed a longer term high fat diet. In my mind, high insulin secretion is the cause of insulin resistance, and therefore the cause of type 2 diabetes and metabolic syndrome. My conclusion with regard to this study: polyunsaturated fats cause higher insulin secretion=bad.
However, in the discussion they said this: “Overweight and obesity are linked to insulin sensitivity and subsequently in older pets to an increased risk of developing diabetes mellitus. Studies have found that intake of polyunsaturated fatty acid is related to a lower risk of animal cardiovascular disease, hyperlipidemia, obesity and diabetes, whereas intake of saturated fatty acids and elevated free fatty acid concentrations are strongly linked to the development of animal obesity, insulin resistance and diabetes. In addition, increased intake of polyunsaturated fatty acids is associated with the improvement of animal insulin action and adiposity”
It seems like they came to the opposite conclusion I did! I don’t understand! jenna.exe is not responding!