It depends. If you’re saying every “calorie in” is equal, and the body blindly burns, stores, or responds to each “calorie” equally, then I disagree. If you’re saying “calories out” is a function of body weight, age, sex and a TDEE calculator plus a sum of movement, and is not greatly affected by the “calories in”, I also disagree. CICO theory says if you want to lose weight just eat less calories relative to activity level. The view is overly simplistic to the point of being invalid. The argument that CICO proponents use is “thermodynamics” or “math” as if the body absorbs energy from temperature differential or the sun, or if we are simply a leaky cup that slowly outputs “calories” and must be replaced with more “calories” at a different rate than what is leaking in order to change the mass balance. 
Not what I am saying at all. Calories in calories out (for me at least) only means that if you consume fewer calories than you burn you will lose weight, if you consume more than you burn you will gain weight.
There is of course going to be a margin of error in measuring those calories as well as a difference in quality of those calories.
Good sir - I prefer to throw my baby out with my bathwater. Don’t ruin this for me. 
Would you agree that it is possible to eat 3000 calories and lose weight while eating 2500 calories and gaining weight, assuming identical physical movement?
If by identical physical movement you mean equal caloric burn than obviously no lol.
you know what I find funny about ‘bro science’ is that I assume they mean gym bros, and by that I think of huge dudes who lift massive amounts of weights and could snap most cyclists in half with their grip strength alone…And then I think…
How you get so big and not know nutrition?
Cause like…I don’t know about you, but I think gym bros are pretty dialed on nutrition generally. Way better than a bunch of weight weenies. 
The first ever diet advice I got was from a body builder who was a personal trainer and he was locked into real dietary science. He also looked like a side of beef stuffed into a singlet.
Any person my height who weighs 20kg more than me and has a body fat <6% is a true dietary genius.
don’t crucify me, meant mostly as a joke to lighten the mood in this thread. oh man, image generators make me laugh
How would caloric burn change if you have the exact same physical movement, rest, thoughts, etc?
I actually LOL’d 
Does one pound of feathers or one pound of iron fall faster if there is no atmosphere?
(I agree with you, just making a physics joke.)
I clarified because I wanted to make sure you were saying that someone eating fewer calories could somehow magically gain weight whereas someone eating more could magically lose weight compared to each other (again assuming the same caloric burn)
Oof a true physics paradox! If you consume the joke you must then laugh to release the energy, otherwise implosion results and a black hole opens in the thread.
What you eat can in fact change the energy balance to the point that the 3000 calorie diet can in fact induce fat / weight loss, where the 2500 calorie diet can induce weight gain. The food you eat has more than calories, macros, and micros. But since only the calories matter according to CICO, it’s tough to explain that when the prerequisite understanding of how the body adapts and changes to the inputs is thought to be irrelevant.
I would absolutely love to read the study you are getting this information from. It would be quite revolutionary to show weight gain consuming 2500cal and weight loss consuming 3000cal with identical caloric burn.
The number of calories eaten is not the same as calories entering your system. The real number for “In” might be only 2400 for example.
And this isnt a quibble. This very distinction is why people say (incorrectly) calories in/out doesnt work.
Posted this above, but things have since devolved.
https://www.nature.com/articles/s41467-023-38778-x
This is the nearest study I’m aware of addressing this, and they actually do a pretty good job. They put people in a “metabolic ward” where they can precisely measure food intake, energy expenditure and poop. They then feed them either a “western diet” (lots of simple sugar and fat) or a diet made up of whole food and lots of fiber.
Their finding is that both groups eat similar total calories (as measured in a bomb calorimeter) and expend similar amounts of energy and both report feeling equally sated following eating. But the whole food diet leads to 116 +/- 56 additional calories lost in feces per day. Basically this diet allows less-digested food to make it deeper into the gut to feed microbes, so you end up feeling just as full but pooping out more calories.
Extrapolation given this premise: If you maintain an even CICO with these two diets, same total calories in, same activity level, same degree of satiety etc., you lose ~1lb/month on the whole food diet relative to the “western” diet.
THAT SAID, this is nowhere near a 500 calorie swing as suggested above, and represents a maximally divergent pair of diets.
That sounds totally reasonable, and it makes sense. It is incredible though, that we’re talking about a 100 cals per day difference which is not that much in the grand scheme of things.
So the person most of the thread ganged up on was right!?
no.
You can eat that same whole food diet, but eat more, and you’ll gain weight if you don’t expend more.
Pull any trick you want, take ozempic, eat nothing but fiber, at the end of the day, what your body absorbs = your budget. If you take in more than you use, your balance increases. If you use more than you take in (absorb) your balance decreases.
Yes, math still works. Energy doesn’t come from nothing. Given a rational approach to eating, eat less / exercise more both work. Changing from eating only carrots to eating only ice cream…not rational. move along, nothing to see here.