Introduction:
Leslie came into my office worn out and exasperated. She was thirty- six years old, but she felt like she was pushing eighty. She was overweight, a trend that started in her late twenties while taking the antibiotic minocycline for her acne. She struggled daily with fatigue, sluggishness, insomnia, and lack of motivation. Her skin was broken out, her hair was thinning, and she had persistent loose stools. On top of all this was her extensive list of medical ailments: irritable bowel, type 2 diabetes, hyperlipidemia, autoimmune thyroiditis, depression, and anxiety.
After seeing several other GI doctors, a chiropractor, a hormone specialist, and an expensive cash- only functional doctor, she was confused and frustrated by the conflicting recommendations. Here she was at thirty- six, on four different medications with ten supplements to boot. “This isn’t the life I envisioned for myself,” she told me on that first visit. “I’m way too young to be feeling this old.”
Much of her frustration stemmed from not knowing what to eat. What should have been simple had become so complicated. She had gone Paleo in her late twenties to combat weight gain and she soon progressed to the Whole 30. She felt better for a short time on those diets, but when the weight gain and fatigue slowly started to creep back in, she desperately searched for a new diet solution and tried eliminating phytates and lectins. She’d been gluten- free for almost ten years and by the time I saw her in my office, she had completely eliminated grains, legumes, dairy, and nightshades. Her diet now consisted mostly of arugula, avocado, grass- fed meat, and bone broth, with very little variation. At times she’d test herself with some beans or whole- wheat bread, but she’d experience gas and bloating, which the diet gurus she was following warned was proof of inflammation.
“It is maddening to follow all the experts’ recommendations religiously and do exactly as I’m told, only to feel worse than ever and see my weight fluctuate like a yo yo!” she exclaimed. With each progressive elimination, she’d see at most short- term improvement, only to slide back into the same exhaustive pattern. The last straw came when she tried the ketogenic diet to lose weight, but it just made her diarrhea worse and it was now a bigger problem than ever.
At this point in our conversation, she was physically slumped forward, elbows on her knees, staring at the ground, eyes welled up with tears. I pulled my chair closer to hers and leaned in so we were on the same eye level.
“Leslie, it’s going to be all right. We’re going to get you better.” She looked up, a glimmer of hope in her eye. “I totally get your frustration. This is the most confusing time in human history for people who just want to get better. Too many experts saying too many different things. I need you to trust me. If you’re with me, then this is rock bottom right here, right now. Today is a fresh start for you with a new approach that makes you feel better and restores the real version of yourself that has been missing these last few years.”
Over the following months, Leslie and I worked closely together to make some major changes. We took her off most of her supplements and slowly reintroduced diversity back into her diet. Foods that she had been told were off- limits were brought back at the right time, in the right amount. She began to really enjoy her food for the first time in years. The restrictive diet had been challenging, boring, and futile for her. She got rid of her bone broth and tapered down on her animal product consumption while increasing fruits, veggies, and even whole grains. Artificial sweeteners and processed foods stayed on the sideline. Beans came back on the menu! And while the process wasn’t always easy, we worked through it together.
Front and center in her new way of eating was fiber- rich plants— fruit, veggies, whole grains, beans, and legumes. Why fiber? Because as you’re about to learn in this book, fiber is the heart and soul of true gut healing, and true gut healing leads to better health in everything from your cardiovascular system to your brain health to your hormonal health. It’s really that powerful.
When Leslie emerged on the other side and settled into her new approach, she was beaming with energy. She was having fun experimenting with all the new foods that she’d previously eliminated. She now knew exactly which foods she was sensitive to and was able to include them in her diet on a regular basis by simply being careful with portion size. Twelve pounds had melted away. Meanwhile, getting Fiber Fueled reversed Leslie’s diabetes and dramatically dropped her cholesterol. She was able to reduce the dosage of her thyroid medication, and she was back to having normal bowel movements. Best of all, she felt like herself again: alive, optimistic, and excited for the possibilities ahead of her.
Getting Fiber Fueled can help you with whatever you’re struggling with, too, whether it’s weight gain, hormone imbalances, digestive issues, or you just want to feel better in your own skin. I know this because I’ve seen it in Leslie and in hundreds of my own patients. Now it’s your turn.

The Fiber Fueled program
Perhaps you’re one of the many Americans suffering with digestive issues: heartburn, abdominal pain, gas and bloating, diarrhea or constipation. I know there are at least seventy million of you out there because I personally published that statistic in Gastroenterology, the top American journal in my field, just a few years ago. Without question, gut health starts with the foods that you eat. Unfortunately much of the advice being offered by popular “experts” is dead wrong. I’ve grown tired of watching bone broth and grass- fed meat be touted as gut healing. There’s not a single study to support that, not even a crappy one. Instead of offering recommendations based on trends and pseudoscience, my program offers you a scientifically validated approach that will truly heal your gut by restoring order to your gut microbiome.
Do you have a sensitive stomach? Do you have trouble processing certain foods, like beans, broccoli, and gluten- containing grains? Food sensitivity has become a major issue worldwide, with an estimated 20 percent of the world’s population suffering from some form of food intolerance. I see it every single day in my clinic, and I’m going to share with you the strategy I’ve devised for my own patients to help identify exactly which foods they are sensitive to. I’ll also share my easy, step step plan for how to reintroduce those foods to eliminate the sensitivity and get back to enjoying them again.
If you’re one of the millions of Americans who have an autoimmune disease, then this book is for you, too. Seventy percent of the immune system resides in the gut, literally just a single layer of cells separating it from the microbiota. It’s hard to separate the two— they rise and fall together. By optimizing your gut microbes, we can help get your immune system back on track.Do you or someone you love have heart disease, cancer, a history of stroke, or Alzheimer’s disease? These are just a few of the dangerous and all- too- common conditions that can improve with this plan.
The Fiber Fueled approach doesn’t just benefit digestive disorders. In fact, this is literally the only diet plan that’s been scientifically proven to actually reverse heart disease.
Maybe you consider yourself pretty healthy and just want to stay that way. That’s the situation I’m in as well. I haven’t always been in great shape, but right now, by practicing what I preach, I feel fantastic. I’ve lost nearly fifty pounds, I’m back to my college weight, and I feel like I’ve actually reversed the aging process. There’s real science to support that. This is the only dietary approach shown to lengthen telomeres, which is the part of our cells that cause aging as they get shorter. Longer telomeres have been suggested to indicate slow aging and reduced risk of heart disease, cancer, Alzheimer’s, and Parkinson’s.
You’re going to learn in this book that you are one of a kind with a gut microbiome as unique as a fingerprint. So there is no one-size-fits-all when it comes to diet. Something that works for another person may not work for you, and that’s driven by the individual nature of your gut microbiome. But if you’ll treat me like your doctor, mentor, and lifestyle coach, I’ll walk you through a program that will be personalized and tailored to your unique needs and ultimately guide you to the vibrant health that you deserve.
This book is the consummation of everything I’ve learned about gut health during the two decades that I’ve been grinding to become the best doctor I can possibly be. With the Fiber Fueled 4 Weeks (see Chapter 10), I’ll show you how to use a healthy diet, lifestyle, and high- quality supplements to address the root cause of your problems. This isn’t just a treatment plan; it’s a way of life that will help you discover your healthiest self. Your symptoms will dissipate, your doctor will be shocked when your medicine ends up in the trash, and you’ll enjoy the vibrant health you’ve always wanted.