Comment by arcticbull

> and (3) your metabolism slows down in response to, specifically, caloric restriction diets and your hunger rises which makes it difficult to estimate your calories out without indirect calorimetry.

This is the critical one that leads people to correctly argue CICO is largely useless for attempting to lose weight: the "CO" part of that is highly variable and is not merely a matter of being active. The body has all sorts of mechanisms that it can adjust to achieve the amount of storage vs burning that it wants to do, regardless of the amount of food consumed or the activity level.

Why are people trying to estimate calories blindly? You have to look them up in some sort of system and log it in a food journal for the tracking to be any good at all.

It works for everyone.

Full stop.

Even if your metabolism slows down in response to caloric restriction, it does not move the needle to any appreciable degree.

Because it takes energy to do. It just does, you cannot fool physics.

However, measuring calories is incredibly difficult. Both in and out. Also, if you put 5000 calories worth of food inside of you, but then immediately vomit out 4500 of those calories, you've only really consumed 500 calories. You can overwhelm the system.

If you can restrict yourself to consuming at a caloric deficit, you will lose weight.

That's difficult however. Because if you pick a target calorie amount, you will see less progress as you lose weight. Because of math. 1500 is half of 3000, but only a quarter of 2000. People get fixated on 2000, as if we operate based on 2000 calories a day. But if you were previously consuming 3000 calories a day, your weight requires 3000 calories a day. So when you drop to 1500, you are going to lose about a pound every two days for a while. When you get to about 2500 maintenance calories/day, you're going to slow down to a about pound every three days. This is not your metabolism "adjusting". You weigh less, it takes fewer calories to maintain that weight.

And you will be hungry. It will suck. And you have to be meticulous in your record keeping. There are no "free" calories.

And we're not even getting into the mental component of all of this. What's been termed as "food noise". And it's one of the things that people on Ozempic and the like notice the most, they stop thinking about food. And food addiction is one of the absolute worst addictions to have. Hands down. With just about every other addiction, abstinence is an option. Alcohol, gambling, heroin, cocaine, meth, etc, none of that is necessary to live. We need food. We need to eat. You cannot avoid food. You have to actually develop discipline. Teetotalers do not have discipline. They avoid the issue altogether.

So CICO works, but it's incredibly difficult to do for lots of reasons that are not related to the biology or physics of it.

FYI, GLP1 drugs are CICO - they work because they reduce calories in.

It CICO is physics, not a complete instruction set for life. I dont understand why it makes people so angry.

People not being serious about diet and exercise doesn’t mean it doesn’t work. Look at reality tv where there is calorie restriction, like Alone or “Survivor” and everyone loses weight. On the former in particular people have lost like 40 pounds in as many days before and have lost so much weight so fast that medical teams have pulled them from the show.

This is like saying most people barely use 5lb dumbbells when told to work out, so working out must not work. Like, of course major lifestyle changes take willpower!

Actually if you just eat lean protein, you will become ravenous because of the lack of fat. Humans need to consume fat, if there is a lack of carbohydrates in diet. If you eat only lean protein you will die from rabbit starvation. Check out this:

https://www.thecanadianencyclopedia.ca/en/article/rabbit-sta....

CICO works if you have the patience and discipline to make it work, which few do. At some point it becomes too unpleasant to keep reducing calories or to measure and track everything. Life gets in the way.