Yes it can be effective but thats exactly the point - most people don't break them correctly, end up bingeing, and have next to no deficit at the end and don't lose weight.
It's all very well saying how you'll break it, it's quite another thing when you are literally starving trying to limit yourself to a couple hundred cals of veges after a fast.

 

Long fasts, in my experience, are futile. You will end up eating reactively. It's a biological imperative. They are also dangerous. Please research refeeding syndrome if you haven't already. That comes on slowly, but it can kill you.

I do have success with the occasional short fast, though, of 24-36 hours. I just make sure that I wait at least seven to ten days between my fasts, and before I start, I make a plan for how I will break it. Sometimes I even make up my meal in advance, so that when it comes time to break the fast, I can just warm it up and not even have to cook. My post-fast meal is typically small, but has some protein and fat. I particularly like soups, because they feel very satisfying on an empty stomach. It's a fool's errand to decide how you'll break your fast when you're already hungry.

 

Fasting is great for weight loss if you do it long term, but you will snap and start reactive eating which has nothing to do with lack of willpower and discipline by the way.

 

don't mind it. you can find several blogs outside mpa that they managed to keep the weight off.