It is pretty simple in my mind, especially on the internet to show.
Type 1 diabetics make no insulin and store no fat, they could eat 50k calories a day and could not gain weight because insulin is what stores that excess as fat.
Calories ONLY matter to the extent that they affect your hormones.
Edit to add that I have heard on a few podcasts now of T1s messing with their insulin in a bid to stay skinny, very dangerous.
Another thought provoking way to answer CICO advocates, and I’m paraphrasing someone else I read:
You’re not losing weight because you’re eating less
You’re eating less because your body is eating fat
Exactly. That’s one of the main components that make “counting” a futile effort. We know the maximum number of calories you can get from a lb of fat per day, but there’s no way to know exactly how many calories your body is ACTUALLY getting from stored fat day to day. I think @richard mentioned a test that can measure it, but I’m guessing most people that set a specific caloric goal, haven’t done that test.
This is exactly the defensive response I expected.
Whatever is going on with hunger for me doesn’t work well in either direction. Especially when I’m not eating carbs, I don’t get especially hungry either. I have no idea exactly how long I would have to go before I got a starving feeling, but it’s somewhere past 96 hours because I’ve done that a few times, and I wasn’t starving at the end.
“No no, color blind person, you’re just not doing it right.”
How was that a defensive response? I was being serious. If the only satiety signal you have is when you’re physically stuffed and can’t cram any more food in, then I’d imagine you feel hungry a lot. I know that’s how I always felt pre-keto.
You’re the only one that keeps suggesting that. I’ve never told anyone they’re doing anything “wrong”. The only thing I’ve ever said is that it seems many people on this forum that have issues with their satiety signals also admit to drinking diet soda and using artificial sweeteners regularly, so I wonder if there’s s connection. Even if there is, that doesn’t make it “wrong”. If your way is working for you, great.
Interesting, Dr. Fung discusses that here also:
Leptin & Insulin Resistance Balancing Tips w/ Jason Fung, MD:
In the absence of insulin, yes. That is why diabetes mellitus (“the sweetened siphon”) was given its name. Until the discovery of insulin, Type I diabetics regularly starved to death because they literally pissed out all their glucose. Type II diabetes is a disorder of insulin resistance, not insulin production, so it is a totally different beast, except for the end stage, when all the pancreatic beta cells in the Isles of Langerhans (poetical name, isn’t it?) are burned out and can no longer produce any insulin.
I’m curious though. If a T1D eats fat, wouldn’t they go into ketosis and burn fat for fuel and yada yada ya, just like anyone else? Wouldn’t they be the ultimate ketone burners because they literally can’t access any other type of fuel? Did no one think to feed them fat???
Or is it that they can’t store any fat because there is no insulin to move it into their cells, so even a short period without fat ingestion could be a crisis …
Absolutely! Except who only eats 1500 calories of doughnuts? I’m sure that the couple of dozen I used to eat in one sitting containted more calories than that! 
But again, the point is that 1500 calories of carbohydrate will get turned into glucose, stimulate insulin production, and either be burnt in the muscles or stored in the adipose tissue—along with any fat consumed. Whereas 1500 calories of fat in the absence of carbohydrate will stimulate no insulin and will therefore be available to be metabolized directly in the muscles and other organs capable of burning fatty acids or else turned into ketones by the liver for those organs that can’t.
As Dr. Phinney puts it, “It’s not that we are what we eat, it’s that we are what we store from what we eat.” And as Dr. Westman points out, “Yes, calories count, but you shouldn’t count them.”
I feel like I’m being turned into a devil’s advocate the longer this discussion goes on. I understand how keto works. I am in support of the concept of eating to satiety and I understand that the natural calorie regulation that the body will offer most of us if our satiety cues are working is a significant part of why keto is effective.
All I’m trying to do is come up with a reasonably plausible, very simple explanation of why the type of calories we eat make a difference to weight loss. Something to make people who have absolutely no knowledge of keto or biochemistry 1. back off a little, and 2. maybe just maybe say, “hmm, you know, that makes sense.”
The problem is that none of the calories they ate got stored at all. Yes, Type I diabetics can go into ketosis, but in the absence of insulin it is ketoacidosis, which is very quickly fatal.
Edit—not sure this is entirely relevant, but I’ll leave it: Also, Dr. Georgia Ede says that the brain requires a certain amount of insulin in order to work properly. Don’t know where she got it, but the statement is, I believe, in her lecture entitled “Our Descent into Madness: Modern Diets and the Global Mental Health Crisis,” which has been posted several times on these forums, so I won’t post it again.
But they didn’t die immediately and they weren’t mentally compromised, so either they were making a little bit of insulin or insulin isn’t 100% essential for brain function. … o well anyway, not really part of this discussion, is it, just another fascinating rabbit hole. 
Peeing out glucose happens with type 2 diabetics as well - it’s why we’re prone to yeast infections (even dudes).
People have a fairly intuitive notion of this in my opinion, though it may not be obvious.
Should you give your kid cake for breakfast? Most people wouldn’t (despite most cake being more nutritional than most kids cereal), people also know you don’t want to give kids soda all the time. Why not? Most will say they get wild, rot your teeth etc. so they know a calorie is not a calorie, they affect you differently. People ‘know’ that 100 calories of vegetables is better than 100 calories of candy. If type of calorie didn’t matter we would all eat blizzards and pizza all day and diets would just be small blizzards to keep calories lower.
But fat makes people fat they might say. People KNOW about beer bellies, beer is almost all carbs so why is it known to everyone to make big fat bellies?
It is almost all brain washing and old wives tales. Soda for breakfast is horrifying but the same amount of orange juice contains about the same amount of what makes soda bad and people consider that a great thing to have at breakfast. Do the vitamins magically make it better?
And for the scorched earth approach, what will happen if I, someone requiring 2,000 calories per day, drink 1,500 calories of vodka everyday instead? You’d lose a little weight on your way to a fairly quick death. What about 1,500 calories of protein? You’d lose a little weight on your way to a fairly quick death from protein poisoning (rabbit starvation). Now what about 1,500 calories of fat? While the muscles would not be in the best shape for the long haul, you could survive decades. And lose a little weight.
All 3 of these have the same calorie input but only one doesn’t kill you.
There’s a limit to how simple it can be, Karen. Why do the type of calories we eat make a difference? Because of our hormonal response. That’s going to require further explanation, even though it’s the most straightforward reason behind the epidemic of obesity, metabolic syndrome, Type 2 diabetes, etc.
Paul –
A really good analogy I once read that illuminated the difference between carbs and fat with respect to energy partitioning during a keto diet, and I don’t remember who to properly credit, went something like this:
"If you are not insulin sensitive and you eat carbs, it can be like making deposits into a bank account that you can never withdraw from. And the account continues to grow and grow …
Whereas if you eat fat, you can make both deposits and withdrawls from that account."
@kib - here it is, short and sweet: “CICO regulates weight. Hormones regulate CICO. And what and when you eat regulates hormones.”
This is persuasive because you start off with a point of agreement. It’s not either/or. (on the contrary, if you say “calories don’t matter”, they don’t hear anything you say afterwards).
Once you both agree that calories matter, then you can ask them why they think some people’s set point is 150 pounds and others is 400 pounds. That can’t be explained without acknowledging differences in metabolism, appetite, and energy partitioning. Which brings in hormones. Which bring in the behaviors to affect hormones.
Keto WOE —> hormones —> CICO —> weight
