Great advice from doctor....bicycling and carbs
That is a good one.
Though I’ve been reading Burn by Herman Pontzer (sadly, does not seem to be a fan of keto but loves carbs instead), and the amount of calories he believes we burn for exercise is abysmal Jogging is something like 0.69* weight per mile, so 69 calories each 100 pounds. Cycling is way worse, 11 calories each 100 pounds per mile, but that’s at 15 mph I think. I’ll have to look again tonight, but I remember the calories being very small.
Sounds pretty good to me. So a 145 lb or 66 kg person is going through ~100 calories in a mile. I’ve heard things close to that since the 1970s. Pretty disheartening to think about - eat that small hamburrger, and want to burn it off? Just run 4 or 5 miles or 7 or 8 km. 
The weird thing is that I get hungrier when I exercise. Go jogging Sunday morning, a simple 2 mile jog with my dog, and I’m hungrier (say, relative to Saturday when I did no exercise). One would think that the calories burnt were so few your body would say “Don’t really need any more calories for that!”.
I very rarely cycle that fast. 15km/h is more like that.
But it sounds super little, I usually guess more, not like I can have any idea, it’s VERY individual anyway, it matters if we do it regularly etc.
Good thing that mere existence of a big land mammal as a human costs a cute amount of calories already 
(Or not, we need to feed a lot and buy food… But we get joy through it…)
And it would be horrible if exercise would cost as much as calculators and clocks and whatever things say… For the active ones, at least, not for me particularly…
In my case, it depends on the time. Nothing can make me hungry in the morning but if I do any exercise after 2pm, I probably get hungry. I do that anyway but it’s really torturous when uphill cycling 
Or maybe not anymore, it was so long ago I had that problem.
And walking (except when I already would get hungry anyway) usually makes me more satiated. More intense exercise is different.
The body has its own logic, calories burnt… Pffft. I get hungry if I eat 500 kcal when nicely satiated (and it’s not early morning as this tiny meal is actually enough for me in the morning. zero is enough and the satiation lasts way longer though). Or when I eat a bunch of carbs after a decent sized, very satiating carnivore meal (very very rare but I am me, it happened)…? I get really hungry again and need to eat a bunch of food more.
It would be so easy if everyone would just be hungry according to their energy balance…
“Weird” is not the word I’d choose. It’s to be expected. You are fulfilling the “move more” part of the standard advice, which is designed to increase the gap between energy expended and energy taken in. And as numerous people have pointed out, eating less and moving more are exactly the things we do when we want to work up an appetite, no?
You know, I’ve always thought the idea that calories in were unrelated to calories out was a weird one, and as you note, people like Gary Taubes have pointed out that if you’re going to go to what you know will be a great dinner and want to eat a lot, one thing you can do is to increase hunger by jogging. Or maybe skipping lunch (for carb burners anyway).
But what I’m currently struggling with is the following. Pontzer believes there’s a high calorie “ceiling”, where if you try to cross that ceiling, your body will reduce calories so you’re near or at that ceiling. Makes a lot of sense to me.
But then I think Pontzer believes (I’m only partway through the book, so I’m not totally sure) that if you want to lose weight, you have to decrease calories.
But I can easily cite studies where people who cut calories have their basal metabolic rate decrease. To me, this means there’s a “floor” too, where your body will take action so you don’t go below that and to protect itself.
If there’s both a ceiling and a floor, though, how does anyone lose weight? You can’t increase calories out, as your body compensates; you can’t decrease calories out, as your body compensates.
Do you have this narrow window within which you can do something?
It’s one reason the MIMO idea makes sense to me: eat more mass, gain weight; eat less mass, lose weight.
How adorable. I merely need to be me! Skipping lunch may be needed, on any woe, for somewhat different reasons. But the less carbs I eat, the more important it gets I suppose… Not easy to tell as there are multiple factors and I changed anyway.
But if 3 hours passed and the meal is the “right” kind, I can eat my 2000 kcal, no problem. Going beyond that, I probably can use some exercise (but I can just force in more food, not my style but I met such a tempting dinner a few times in my life), I can’t jog for, like several hours (not even 10 minutes, actually) but hiking or cycling is possible. Lifting probably does little…
But I can’t imagine why I would want to eat more than I am used to (for my first meal. my dinners are often pretty small). It doesn’t sound healthy especially mentally… Oh well.
The ceiling makes zero sense to me but I write about that before… And I don’t care anyway. I need to exercise as much as I comfortably can and eat as little as I comfortably (or maybe semi-comfortably) can, that is the main thing for me. Luckily it’s this simple. Super hard and difficult to do but the base is simple.
If I want to lose fat, I need to eat at a deficit (it’s actually true for everyone, how else would it work?). Decreasing calories may be a fail for multiple reasons. I need a deficit, not just eating less. I ate less in the very beginning of low-carb and it was still over my energy need But indeed, some people has a not healthy body that responds to any deficit with metabolism lowering, immediately at that. Sounds horrible. They able to stay overweight eating barely anything from my viewpoint and they probably feel pretty awful too, our body doesn’t just waste energy, it needs it for proper functioning (expect when it raises CO just to avoid gaining fat, that’s neat). We really don’t want to be more “effective”, it’s not that, it’s some kind of starving instead of losing fat.
That’s why this idea is obviously wrong. CO is subject to change. But if we look at people who gain, cut, getting more and less active etc., it’s quite obvious, isn’t it?
But the body compensates sometimes, it’s just not as creepy… If I drastically raise my CI, my CO goes up too, it’s totally a thing. And if we starve, our CO goes down. There are surely other, more interesting balancing acts and they may or may not be very individual… But having the same CO all the time, no matter what we do, that’s definitely very untrue Many of us experienced that.
Sadly, I hardly can escape my big maintenance window. But theoretically it’s possible.
But for others… Yes, there is some cute window where healthy fat-loss is possible. But it’s not a fixed window due to changing CO. And it seems there are people where things are more complicated than in my family anyway. In a lucky case, we feel how and how much we should eat so we don’t force some wrong food intake on ourselves thinking it is the right one.
I only have some educated guess about my usual CO but how can I know if it’s right or if it suddenly changed in the last days…? (And this is without big changes in my activity. I do have some kind of changes there lately.) I feed my body if it wants to be fed and accept the consequences… I am so glad I don’t need to slim down asap for some reason. I like to be safe (and satiated) way too much despite knowing I am a human with plenty of extra fat, not a shrew. I don’t need to eat so often, even a longer famine couldn’t damage me much. It doesn’t mean I am willing to force anything especially lack of food.
But it’s way too late for me for this.
My wife and I have an elliptical exercise machine, and it keeps track of “calories burned.” I don’t know the actual accuracy of it - but it’s like a commercial machine (pretty expensive) and what it reports does mirror what I’ve read over the years about exercise and energy output. Naturally, the more fit you are - the higher your aerobic capacity, your “VO2 max” - the more energy you can go through over time, and the higher your effort, the more you’re going to burn.
I haven’t done it in a while <insert embarrassed icon here> but it usually takes me about one hour to get 700 calories. That’s significant effort but not maximum. I’ve done one hour, two hours (and ended up over 1000 calories). Never gotten close to a maximum effort for a long time, but I wonder what is possible.
Would love to be a study subject, to see how much fat a person can actually lose, per day.
Is that a ceiling on calories in, or calories out? Either might make some sort of sense, but I’d want to see data.
It’s inarguable that losing weight involves a lower food intake, with the difference being made up from stored fat, but people like Eric Westman and Amber O’Hearn always point out that it’s more effective to let the body take care of those things, instead of trying to manipulate the situation.
As you point out, there are plenty of studies showing a metabolic decrease from calorie restriction. There are also a few showing that increasing calories can speed up the metabolism, as well. (I’m sure there are limits in both directions, but the range seems to be broad.)
The proponents of the carbohydrate-insulin model would say that it’s the type of food that makes the difference. Eat mostly carbs, and the body will use some but will store much of that as fat. (The influence of high insulin.) Eat mostly protein and fat, and the body will release excess fat from storage. (The influence of low insulin.) As we know, the real picture is somewhat more complicated than that, but the broad outline does seem applicable. My favourite aphorisms in this connexion are (1) Fung’s (“If you want to store carbs, eat carbs; if you want to burn fat, eat fat”); and (2) Westman’s and Phinney’s (“We are not what we eat, we are what our body saves from what we eat”).
Taubes has a further point, to the effect that some people can eat carbohydrate without much ill effect, and remain in energy balance, whereas other people, even when they eat the same way, but less of it, still get fat. He cites a number of studies showing that when a fat person says, “I get fat even when I don’t eat much food,” it can very well be true. He argues that the advice of lean nutrition physiologists to simply eat as they eat (but less) doesn’t necessarily work for people with a propensity to fatten easily. I also love his calculation of how much extra food it takes to put on twenty pounds over ten years. It works out to about 3 kcals extra per meal. How do normal-weight people know to leave off those 3 extra calories?
Richard Morris did the calculation of how much fat the body will allow to be used in a day, and it’s posted somewhere around here. If memory serves, it’s between 3.0 and 3.5 kcals/kg fat mass, but please don’t quote me. If you’re really interested, you can do a forum search; the last time I tried, it took me over an hour, which I don’t have time for, at the moment (I always forget to bookmark these things; someone kick me please!).
ETA: He also goes into this in Why is the Fat Man Hungry? I believe.
Paul, yes indeed - it goes back to Keyes’ results.
https://pubmed.ncbi.nlm.nih.gov/15615615/#:~:text=A%20limit%20on%20the%20maximum,%2B%2F-25)%20kJ%2Fkgd.
A good thread where Richard has his say: Does this study on fasting show that fasting doesn't work?
What I’m thinking is that in this day and age, studies like Keyes did aren’t going to fly. But - a totally voluntary deal where the subjects go into it knowing the deal should be okay. If nothing else, one could do it on their own, paying for Dexa scans, etc.
Many things can play a role in this. Level of intensity can also play a role, The higher intensity, the more the body prioritizes sugar as a fuel source. If you are T2 your body may also be prioritizing sugar as an energy source, even at a walking pace.
His formula seems to be on the lower side. I will burn roughly 450 calories per hour at a relativity easy pace.
It’s the effect of insulin, which is secreted to drive excess glucose from the blood, in order to prevent damage from hyperglycaemia. And of course, the resulting chronic hyperinsulinaemia also causes its own damage . . .
The switch between fatty-acid metabolism and glucose metabolism has been shown to occur at an insulin level just below 25 ÎĽU/mL of serum insulin. How much carbohydrate we can safely eat and still stay below that number depends on how insulin-resistant we are, of course.