system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If losing weight can be summed up as CICO (calories in calories out), how do low carb/keto diets that have you eating steak, bacon, cheese, cream etc. work when they have such high base caloric counts?

I am subbed to a few weight loss subs, and I notice that there are a number of posters that tout low carb and keto diets, but it logically doesn't make sense to me. If you eat a 1,500 calorie steak, you are still ingesting 1,500 calories of steak whether or not you have it with a side of mashed potatoes or mashed cauliflower.

Enlighten me please :)
gpt
The idea is supposed to be that you still are *in* a calorie deficit, but that you spend less time going through the following cycle:

1. Eat lots of pasta

2. Build up blood-sugar level

3. Build up glycogen level

4. Burn off blood sugar

5. Burn off glycogen

6. Finally, after running out of glycogen, start burning fat.

7. But now you have another meal, so you eat more pasta, back to square 1.

The idea is that taking all the sugar and glycogen away from the metabolic system is like separating a mom from her baby.  The baby will sob and sob and sob, and then forget about her and start playing with his blocks.  And he could play with blocks for hours... but if you bring his mom back, he'll sob as soon as they are separated.  To lose weight you have to burn fat, but your body *hates* to give up the final reserves of energy stored as sugars before getting down to that fat, and people who spend a lot of time in that state are irritable, stressed, and hungry.  Once the actually conversion of fat to energy gets going, it's not as bad.  So if you power yourself mostly through fat, it's easier to go through with it, because you spend less time in the carb-separation temper tantrum.

That is the theory.  In practice, it may just work because when you say "no carbs" you rule out a ton of foods and have to be very picky.