intermittent fasting, is as it says. you fast.
here is an example, eat only within noon and 6pm everyday. or east only 2 meals a day. breakfast and dinner. getting the book is the best way to learn about it.
you can also read the book good calories, bad calories or from the same author, why we get fat.
the cliff notes are, refined carbs increase blood sugar very quickly. increased blodo sugar means you will increase insulin. insulin takes that excess blood sugar and moves it into muscles if they need it or adipose tissue for anything that is left. the storage of blood sugar in adipose tissue is a one way street. on other words you cannot burn adipose tissue as fuel if you are storing. so minimize spikes in blood sugar, which minimize insulin which allows for more time to use adipose tissue as fuel.
intermittent fasting, carb backloading, and a lot of what those books i mentioned above allow for what i just mentioned.
this is my opinion. but what i just mentioned is why calories in vs calories out is not that accurate as well as the law of thermodynamics (as most people apply it usually to support in vs out) when it comes to fat storage and energy needs.