I’d say that a calorie obviously is a calorie - we’re talking about physical matter, here, right down to individual molecules and atoms.
That’s not to say that the different macronutrients will necessarily affect us the same way - due to the differing insulin responses the body can have. If we’re at a relatively high insulin level, our access to our stored fat may be almost entirely blocked, a much different situation than with low enough insulin - this is broadly the context in which a ketogenic diet works for so many people who want to lose weight/fat, versus a diet much higher in carbohydrates.
If there’s no fat storage going on, then the excess beyond what’s used for muscle building, muscular work, and the other bodily processes like digestion, heat production, etc., will be excreted. This would be pretty darn unusual, i.e. normally not much human-diet energy goes through undigested.
I think in practice 5800 calories per day would result in fat gain for the overwhelming majority of people.
I heard a podcast with someone who fed volunteers 3,000 extra calories per day. These were metabolically healthy volunteers (he did not say what the extra calories were, though). I can’t remember the length of time, but it was for a while. The maximum weight gain was 2kg, so a little over 4 pounds (edit: miscalculated, said 2 pounds instead of 4). He said they all felt great and had tons of energy. I assume their basal metabolic rate went up.
Jason Fung in one of his videos relates a story where they tried to do a similar over feeding experiment, but they used pork chops. The subjects could not overeat. They ate a certain amount and could not eat more. (It’s the whole theory that protein causes satiety much better than carbs and better than fat.) They had to change the food to higher carb fare.
And if you liked that video, here’s another one for you. In this one, the theory is that saturated fat causes your fat cells to be insulin resistant, meaning you eat less. Meanwhile, polyunsaturated fatty acids cause your fat cells to be insulin sensitive, meaning you eat more.
And here’s a guy who tested this theory. As further background, some people (here’s looking at you, Stephan Guyenet) believe we get fat because food simply tastes too good. (If you don’t know,Guyenet is convinced we get fat because food tastes too good; in fact, he says not to add butter to vegetables, not because of the fat, but because this makes the vegetables taste too good, so we’ll eat more. Seriously. I’m not kidding.) So, this guy made sure the food he used to test this theory all tasted really good.
You can go down this rabbit hole a lot.
But you also have to realize that we are not closed systems. If you ever looked at your poop and seen part of blueberries or red color due to beets or whatever, we’re not completely absorbing these. Furthermore, if you are breathing out ketones enough to measure them, guess what these are? Potential calories that are being excreted. In fact, for people who believe low carb confers a calorie benefit, in that we use more calories than do high carb people, those excess calories are primarily breathed out of our bodies.
I think it’s like this:
The more you know, the more you realize that we don’t know anything.
I have never checked to see if my temperature was actually lower but when fasting I feel very cold. During Ancel Keys starvation experiments the subjects felt cold even in the summer. Assuming this change in the body is an attempt to save or conserve energy than the opposite which would be wasting energy makes sense to me.
We do seem to like similar resources I watched Mike Eades talk a while ago and have been monitoring hyperlipid ever since. Great stuff. I also may or may not try the croissant diet (which I think was linked on hyperlipid a few weeks ago) for a while, because I do believe that metabolic flexibility is important. But I do want to wait until my insulin resistance has gone down a bit more before I reintroduce some carbs into my diet.
It may not be easy to overeat, but it’s certainly possible to eat a lot more than energy requirement. I think Gary Taubes mentiones some old observations from 80-100 years ago where people consumed 3000+ calories a day while losing weight on a meat heavy diet. So even though satiety management is a big factor, it certainly seems that we use excess carbs in a much more efficient way than excess fat.
People on the Feldman protocol consume a lot calories (ideally about twice the daily requirement in animal fat) and they report that it’s not easy, but it can be done if you eat when not hungry. Obviously not recommended, but an intereresting experiment neverhteless
The metabolic rate does go down a lot when fasting after 3-4 days, that’s why people like Fung usually advise intermittent fasting or alternate day fasting where this doesn’t happen.
But I have my doubts that we can burn a ton of excess energy this way. Some calories, absolutely. So maybe the answer to my question is “a bit of each”: Higher consumption (body heat), higher waste (breathing and pooping out combustable chemicals) and if we consume even more calories then we do get fatter even on a keto diet.
amwassil
(Michael - When reality fails to meet expectations, the problem is not reality.)
#16
Here’s a good layman’s intro to how calories are spent, refs at the bottom:
I did the Feldman protocol and found it very hard. I fasted 4.5 days, then immediately starting eating as much as I could of high fat fare for three days. That’s not normally what I do after fasting this long, as I’m not really that hungry. It did what it should, but I would not recommend doing it that often. (And I have “low” LDL normally, anyway, so it’s not necessary for me to do this.)
Phase 3 was the overeating phase, and this is how they describe it:
I’d call the carbohydrate ( C ) as high carb, low protein, and the fat (F) as still higher carb, low protein. They don’t really say what the fat is.
Here’s the abstract. They ate about 1,200 extra calories a day, so should have gained about 7.1 pounds or 3.25 kg.
You can see how the whole “3.500 extra calories/day = one pound of fat” is totally wrong.
Also, I’ve been trying to eat more stearic acid based on the croissant diet I posted above. I’ve found a HUGE decrease in hunger by eating cocoa butter. Unbelievably huge, to the extent where I skipped dinner (only eat two meals per day) one day and want to skip it every day. In 6 years of low carb/keto, that has NEVER happened to me. If I want to eat OMAD, I have to force myself to do that. With cocoa butter, it came naturally. I physically was not hungry. In fact, I’ve had to cease eating cocoa butter, otherwise I get too full to eat over the holidays.
amwassil
(Michael - When reality fails to meet expectations, the problem is not reality.)
#19
@ctviggen Bob, how much cocoa butter are you eating each day? I’ve been eating abut 50-100 grams per day for about a week. I haven’t noticed any change in my appetite. In fact, if anything I’ve noticed a slight increase in morning hunger, which might have nothing to do with the cocoa butter. I’ve also decreased total daily calories by 2-300 during the same time, so that is possible/likely to be the source of my increased morning hunger.
Are you eating cocoa butter or cacao butter? I’ve been eating cacao butter. My understanding is that the only difference between the two is that cacao butter is extracted at a lower temp (max 115°F) than cocoa butter. Nutritionally, they are identical. Although most cocoa butter ends up in the cosmetic industry.
Again, this really isn’t true. Fung mentions that after fasting 4 days, the average metabolism is 13% higher. There is definitely individual variation, i.e. some people really feel “cold,” others do not. But it’s really not correct to say that after fasting only 3 or 4 days, one’s metabolic rate “goes down a lot.”
Base metabolic rate is down by 25% after 28 days (https://www.ncbi.nlm.nih.gov/pubmed/7275468). We don’t have a lot of data, but the biggest loser study shows a metabolic rate of 500 calories below baseline after 6 years in which patients had regained most of the weight (RMR was adjusted for weight loss). https://www.ncbi.nlm.nih.gov/pubmed/27136388
The lowering of RMR with prolonged fasting is real. The only thing we’re talking about is whether a 3-day fast will lower RMR in the long term or not, there we obviously have no data. Maybe it does, maybe it doesn’t.
Well, as before, Dr. Fung mentions that in the 4th day of fasting, the average metabolism was increased by 13%. The increased secretion of hormones that rev us up is real - it’s easy to test for increased noradrenaline/norepinephrin. There certainly is individual variation, and some will be above that 13% figure, and some will be below it, but the average increase in metabolism was there, as was the confirming increase in V02.
These facts totally fly in the face of “The metabolic rate does go down a lot when fasting after 3-4 days,” and that’s what caught my eye.
All right, cool, man - some good data there, apparently, and I don’t doubt it. (And I wondered, and it’s good to know that.) No question that eventually the metabolism will slow. Now of course - the body weight is declining during fasting, so after a substantial number of days of fasting, metabolic decline would be expected, all other things being equal. 28 days will usually have people down 14-20 lbs on fat (really big people can lose more per day) so even if maintaining the same metabolic rate per unit of body mass, an overall decline would eventually be expected.
I’ve got about 30 fasts of 3 days to 12 days duration in, and things vary - I’ve felt “normal,” or “sluggish” or “really jacked up…” I don’t doubt that after 28 days I’d have a slower metabolism. And I really wish there would be exhaustive studies on fasts of many lengths.
The ‘Biggest Loser’ contestants weren’t fasting, as far as I know - I think they were eating less (restricting calories) and working out, even working out like crazy.
This illustrates why this is a complex calculation. Over 28 days, you should lose a lot of weight. If you determined your metabolism slowed, would that solely be due to your lost weight? It’s like when people lose muscle mass when they lose a ton of weight. Is that only muscle they lost due to not needing it to move their previously much larger bulk around?
Say you fast 5 days and do DEXA scans before and after (and assume DEXA scans are perfect, which is never the case). You lose some lean body mass. What does this mean? Phinney thinks this is bad, while Fung thinks this is good. Who is correct? I personally think Fung is, because I’ve done tons of fasting and gained muscle mass while losing body fat according to DEXA scans. But I could be wrong, as I’ve never tested over one fast, only over many months. Maybe when I was eating, I compensated for the “muscle” mass I lost when fasting?
Unless we have large scale studies with many people, we can’t really answer these questions.
amwassil
(Michael - When reality fails to meet expectations, the problem is not reality.)
#27
Don’t want to be a smartass, but RMR is mainly based on lean mass so it doesn’t go down proportional to the weight. Curious. How does Fung measure RMR? It’s not exactly easy to determine. Maybe different measurement methods lead to different results.
The biggest loser study dscribes how RMR is measured: The RMR measurements were performed using indirect calorimetry following a 12-hour overnight fast. Participants rested supine in a quiet, darkened room for 30 minutes before making measurements of VO2 and VCO2 for 20 minutes with the last 15 minutes used to determine RMR according to: which assumes that protein oxidation contributes 15% to the energy expenditure.
Edit: It might make a difference whether you come from low carb or high carb when starting the fast. After all, the body decreases RMR with an undercaloric high carb diet but doesn’t with a low carb diet (unless it’s extremely undercaloric).
The muscle loss is almost negligible unless you fast for a long time, 12-15 grams per day and declining with time. https://www.ncbi.nlm.nih.gov/pubmed/6764569 We can measure this pretty well from some nitrogen compound which (as I understand) is excreted via urine exclusively.
Still, I recommend drinking a bit of bone broth when fasting. It will replenish electrolytes, reduce keto flu and give just a little bit of protein, for the price of a minor insulin response that shouldn’t impede fasting significantly.
Bob, it definitely is complex… For many people it’s no big trick to lose 5% or 6% of body weight during a 28 day fast, so some decline in metabolism would be expected, all other things being equal. It’s not going to be linear, though - we’re mainly losing fat, which is metabolically “cheap” to maintain (versus muscle, nervous tissue, etc.). Take it to a further extreme - the average person who weighs 150 will burn more than half the calories of the average person at 300.
There’s also the thermic effect of food. I always read that this is somewhere around 10% of our energy expenditure - when we’re eating, of course, not fasting. So, if there is a “real decline” in metabolism due to fasting, I’d say allowances have to be for weight loss and no food being processed, i.e. ‘all other things will definitely not be equal.’
I’m not saying this explains all metabolic slowdown when fasting. After some time, I do think the body starts trying to conserve energy by hormonally adjusting things. I’ve definitely felt sluggish and low-energy on some days of my longer fasts - and I am sure that things would be different if I was eating.
The accounts of long, really big weight-loss fasts I’ve read about are from the 1960s and 1970s, so there were no DEXA scans etc. It’s too bad they weren’t more closely studied - the most I can say is that the people generally looked okay when done fasting. Not sure if they lost more muscle or not, versus what would be expected due to having to move less mass around.
Sometimes it’s water loss from tissues that the DEXA scan reads as “lean” - this will be reversed once eating resumes and hydration/electrolyte balance returns to normal. There’s also the refeeding period after fasting, which does some impressively good things (while not directly related to weight loss or regain, it’s an area that makes me think that fasting at least once in a while is really advantageous).
To an extent, the refeeding period will make some lean mass “reappear,” usually, on a scan, but I don’t know if it accounts for everything.
Especially during the first few days of a fast, there is a significant and measurable nitrogen loss from the body - it does appear that some protein is being metabolized (and I don’t know how much of this is really muscle tissue or not). I’ve seen Phinney extrapolate from this, proclaiming that more muscle tissue is lost than there really is - the nitrogen excretion declines fast as the body goes into full recycling mode. As most of us usually note, too, Phinney has worked with more athletic, often younger people, than Fung. His subjects likely have substantially less fat to access, i.e. they will get into consuming lean mass earlier and more substantially than those whose fat stores can provide all the fuel needed.
I don’t give Fung a total pass - he sometimes over-simplifies things, or generalizes with nearly bumper-sticker style quotes, i.e. “The body is not so stupid as to burn muscle when fasting - this would not fit, evolutionarily, since we’d need to be strong to go out and hunt” (paraphrasing there).
There’s a lot that confirms what he says - the increase in growth hormone, for example, is profound as we get into fasts of several weeks in length, but it’s still not 100% effective at preserving all muscle that was there prior to fasting, and things are not as ‘black and white’ as I feel Fung sometimes portrays them.
I watched Mike Eades talk a while ago and have been monitoring hyperlipid ever since. Great stuff. I also may or may not try the croissant diet (which I think was linked on hyperlipid a few weeks ago) for a while, because I do believe that metabolic flexibility is important. But I do want to wait until my insulin resistance has gone down a bit more before I reintroduce some carbs into my diet.
For many people it’s no big trick to lose 5% or 6% of body weight during a 28 day fast, so some decline in metabolism would be expected, all other things being equal. It’s not going to be linear, though - we’re mainly losing fat, which is metabolically “cheap” to maintain (versus muscle, nervous tissue, etc.). Take it to a further extreme - the average person who weighs 150 will burn more than half the calories of the average person at 300.