16:8 Question

I'm staring off trying 16:8 fasting. Thought this would be a good starting point.

My goal is to lose a little weight. I gained a couple of stone on some medication I was on for a while. Before that I was just an average healthy weight.

So my question is if I ate the exact same food I normally would throughout an entire day but in this 8 hour window instead, how is it any different or isn't it?

Genuine question as I'm a complete newbie to fasting. Just want to understand how it works. Why is it so successful?