Jessica Simpson -- The Super Secret Weight Watchers Diet Plan

Jessica Simpson kept herself to a strict Weight Watchers regimen in order to lose SIXTY POUNDS after her pregnancy -- a regimen filled with low-fat smoothies, protein, and veggies -- and TMZ has obtained her 4-month crash diet plan.

The plan -- crafted by Jessica's former private chef -- closely follows the WW point system, with fancy homemade menu items like egg white omelets, chicken satays, whipped chick peas, soba noodles, and shrimp skewers.

It all kicked off in July with a 15-day smoothie diet: 5 days of 3 smoothies a day (with 2 healthy snacks); 5 days of 2 smoothies a day (2 healthy snacks, 1 meal); and 5 days of 1 smoothie day (with 2 snacks and 2 meals).

For a while, it didn't look as if she'd lose any weight at all -- at least based on her terrible WW commercial -- so we gotta say ... we're impressed.