Quick, answer this question: What's the first food you think of when you think of bodybuilders? More than likely, your answer was "meat," because, after all, we've always learned protein is the key to building big muscles. And who hasn't jealously pictured those buff guys at the gym wolfing down burger after burger?

But as this PETA ad shows, it's not always meat, or animal products at all, that create a body that lifts hundreds of pounds at a time.

Jim Morris, now 78 years old, became vegetarian at 50 and vegan at 65 and believes diet is to thank for his enviable physique.

"I would not be here, and I would not be in this condition now had I continued eating the way I was," he says in a promotional video on PETA's site. He speaks disdainfully of drinking milk and emphasizes the usefulness of the protein in the fruit, beans and grains he ingests.

Last year, a massive study found that those who follow a vegetarian diet were 12 per cent less likely to die of any cause than meat eaters, reported Men's Journal, and as Oprah's site (among many others) points out, eating a vegan diet is far friendlier to the planet.

While a vegan or vegetarian diet might not be for everyone (and certainly doesn't guarantee you'll look like Morris at 78), incorporating more plant-based meals into your routine even once a week can reduce your risk of heart disease and certain types of cancer, according to WannaVeg.

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