system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does intermittent fasting work and why so many variations?
gpt
There's a lot of whacky science saying stuff like since you've not taken in any calories your body goes crazy burning fat or whatever. To be honest it works because you eat less. That is how any diet works, diets like keto or gluten free may have some science behind them but 90% of the results is simply just eating less.

With IF you aren't necessarily eating less, but just try to eat an entire day's worth of food in just a couple of hours, of course you end up eating less. Keto or GF diets, whilst the core of the argument isn't eating less, by restricting what you can eat and by forcing you to consider what you eat constantly, you end up eating less.

New diets aren't magic or anything, losing and gaining weight has and always will be a matter of eating less calories or eating more calories.