The keto diet has transformed the figures of some of the biggest names in Hollywood. But when wellness expert Naomi Whittel gave the low-carb, healthy-fat eating plan a try two and a half years ago, she found a major flaw. “My body wasn’t getting enough fiber-rich foods,” says Naomi, pointing out that a diet lacking in fiber can have negative side effects, such as a weakened immune system and even storage of extra fat.

OK!: Why is fiber so important for women who are following the keto diet?

NW: Not only is it antiaging, but prebiotics are our microbiome’s favorite food — and prebiotics are oftentimes a fiber. If you can get more of it into your diet, you’re giving the little bugs that make up your microbiome their favorite food, and then they perform for you.

OK!: Your book contains some great fiber-packed recipes. What are your favorites?

NW: I worked with nutritionists and dieticians to create delicious things like keto chili and chicken tenders. I also added cruciferous vegetables like Brussels sprouts, broccoli and cauliflower to many recipes because they reduce inflammation and wrinkles.

OK!: Can you recommend a prebiotic fiber for someone on-the-go?

NW: When I was starting the book, I spent the day with my friends at SlimFast and they brought us their Fat Bombs and Meal Bars. I saw that one of their main active ingredients is inulin, which is a prebiotic. I got really excited!

OK!: Do the SlimFast Keto products work within the program you’ve created?

NW: Yes, perfectly. They’re easy, delicious and fun on-the-go snacks.

OK!: Any tips for sticking with a keto diet?

NW: I make sure I’m getting 75 percent of my calories from fat, and I don’t push it too hard. At the beginning it might take a couple of days, it might take a week, but you’ll get stronger and your metabolism will become more flexible.