Right before I joined WW, I tried Slimfast. BLECH! Didn't work at all. First of all, I would drink my shake for lunch, be okay for a very little while, feel starving by the time I got home from work, & then my "sensible" dinner I would gorge myself because I was so hungry!!! Plus, I hated the way the stuff tasted.
I've also done the starvation &, unfortunately, purging combined. I would eat very, very little (like 2 pieces of dry toast & a piece of fruit for the whole day) & more often than not purge that little bit of food.

I thought my multi-vitamin was enough.

It was a sad & scary time & I was doing it to control other aspects of my life. I lost over 100lbs. doing that. When I stopped, I quickly gained all of that back plus more.
By losing weight in a healthy way like I have been since April with WW, though, I have noticed that I feel sooooo much better! It's a great feeling!