Once a lover of bacon and burgers [1], Bob Harper has made a drastic shift to his diet [2] and is now mostly plant-based. "I'm a big fan of eating more plant-based," Bob told POPSUGAR. "Eating vegetables is a great weight-loss tool." But despite being a fan of a plant-based diet, the lifestyle change has been difficult for Bob, who used to be Paleo.

The Biggest Loser star said, "It's been a real challenge for me, because when you find something that you thought was really working for you and you have to go back to the drawing board, it's a big adjustment." Bob mentioned that he was "reluctant" to make certain dietary changes but that the payoff has been fantastic. His new book, The Super Carb Diet: Shed Pounds, Build Strength, Eat Real Food, outlines a more carb-friendly [3], veggie-heavy diet that's geared toward weight loss and maintenance [4].

"I had to go back to the drawing board and figure out how this [new] diet plan's gonna work with me," he said. "My doctors want me to be more plant-based — even more than I am in my book! My book isn't a vegetarian or vegan book, but the way that I'm eating is more plant-based."

Thinking of foregoing animal products yourself? He's got four things he says you need to know first:

• "It takes a lot of effort."
• "It is a challenge [5]." Bob expanded that it was especially challenging for him because he enjoys meat. "After my heart attack, when I was going completely plant-based,
  I was saying to my publishers that I wanted to write a book just about this, and I wanted to call it 'The Reluctant Vegetarian.' I miss eating a good grass-fed burger like I used to, [but] I realize with the genetics that I have to be very careful."
• "Don't rely on all that carbage." No, that's not a typo, just a Bobism. "You see so many vegetarians who say, 'Well, I'm not eating animal protein anymore so I'm healthy,' but I say, 'Look at the quality of the food that you're choosing!' There's so much crap out there. You can't just say, 'I'm a vegetarian so I'm gonna eat french fries every day!' That's not how it works."
• "Be mindful," he said. "If you're going to choose this lifestyle, you have to be mindful and really aware of what you're doing. Do your homework; do your research so you're really feeling strong and feeling good — because all that carbage stuff is going to make you feel crappy."