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With so many "miracle" weight-loss plans out there and everyone sipping diet drinks, why are there so many overweight people in America? After all, losing weight really isn't that difficult. If you want to slim down—and save animals—try going vegan: The results can be astonishing. Most plant-based foods are naturally low in fat and calories and high in fiber. They raise your metabolism and are more filling, so they cause you to crave fewer calories. And research shows that vegans are at least nine times less likely to be chunky than meat-eaters are! If you're trying to slim down, the Physicians Committee for Responsible Medicine suggests a three-week vegan eating plan that's low in fat but will still fill you up.

We recently graded the most popular diet programs in America on how vegan-friendly they were. Continue reading to see how they measured up.

Why has Cheers star Kirstie Alley packed on 83 pounds after her widely publicized diet as a spokesperson for Jenny Craig in 2007?

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She told People magazine, "A vegetarian would probably be eating vegetables. But to me being a vegetarian meant I'm going to eat enchiladas with no meat, and I'm going to eat lots of bread, lots of carbs."

Hey, Kirstie: put the slimy, butter-slicked fork down! Vegans are, on average, 10 to 20 pounds lighter than meat-eaters are, so we promise you'll see results!

If Nia Vardalos can drop 40 pounds by kicking cheese, Kirstie surely would slim down if she said, "Bye, bye, butter!" and gave vegan fare a shot. To help her in this endeavor, a copy of Skinny Bitch is on its way to her, courtesy of PETA.

Written by Karin Bennett