Jennifer Hudson -- My Skinny Ass is DONE With Weight Watchers

Just like most plus size girls who lose a ton of weight ... Jennifer Hudson is dumping her main squeeze -- Weight Watchers.

Hudson says her time with the diet company has been life changing ... a total understatement ... she went from a size 16 to 6, losing 80 lbs, using the product -- and got pretty damn hot in the process.

J Hud linked up with W.W. in 2010 after giving birth the year before.

Company honchos say they assume she will continue using their products.

It sure seems to work better than pizza.