140: The Science Behind Diabetes Reversal and a Plant-Based Diet with Lewis Bertus, PA-C

Prepare to be inspired by Lewis Bertus PA-C, a certified physician assistant and diabetes reversal coach whose personal journey sparked a life-changing discovery for his wife, and now countless others.

In this episode, Lewis reveals how understanding the science behind fat-induced insulin resistance shattered conventional wisdom and led to true type 2 diabetes reversal. He dismantles misconceptions about carbs, explaining why a low-fat, whole-food plant-based approach can unlock healing for Type 2 (and support Type 1) diabetes.

He offers simple, practical meal ideas, guidance on tracking fat intake, and ways to tweak habits even as a plant-based eater. Let’s dive in!

Helpful Links

• lewisbertus.com
• Diabetes 180 Meal Plans
• Instagram: @diabetes_reversal_coach
• Facebook: Diabetes 180
• Clean Food Dirty Girl Recipe Club
• Clean Food Dirty Girl Meal Plan Club – Try Free for 10 Days
• Clean Food Dirty Girl Drop It Club: Plant-Powered Weight Loss

About Lewis Bertus, PA-C

Lewis Bertus, PA-C is a physician assistant and founder of Diabetes 180: a coaching program built on reversing diabetes with evidence-based, plant-forward nutrition. Motivated by his wife’s journey from medication-reliant to diabetes-free, Lewis blends medical knowledge with holistic coaching strategies. His mission: to educate, inspire, and guide clients globally through sustainable dietary transformation.

Transcript (auto-generated, may have errors)

Molly Patrick
Hello everyone, and welcome to the Clean Food Dirty Girl podcast. Thanks for listening to this episode. Today we have a guest on our show, Lewis Bertus, PA-C. Lewis, you work with people who… well, tell me if this is right. Do you consider yourself a diabetes educator?

Lewis Bertus, PA-C
Yes, you did. Very good.

Lewis Bertus, PA-C
That’s included in what I do for sure. I’d more likely call myself a diabetes reversal coach.

Molly Patrick
Ooh, “diabetes reversal coach.” I like it. Let’s jump right in, because right off the bat I want to know more about you, how you got here, and a bit about your story. I’m intrigued by that title because so many people think diabetes isn’t reversible. Let’s start there.

Lewis Bertus, PA-C
For sure. I guess we could start from the beginning—why I got into it. By training, I’m a certified physician assistant and have worked in family medicine for about six years. My wife had diabetes, like many of my patients—really bad. She’d had it for eight years, even before I became a PA.

Going through PA school, you learn all the dangers of diabetes. I was alarmed—thinking, my gosh, my wife could die if she doesn’t get this under control. So I went into practice with an understanding of diabetes, but I had a special connection because my wife was suffering. I was excited to see if I could apply what I’d learned to help my wife and my future patients.

Lewis Bertus, PA-C
As time went on, her diabetes got worse despite numerous medications. She’s the kind of patient who gets every side effect listed on the bottle—joint pain, upset stomach, weight gain—so there were lots of medication adjustments. Even on medications, it was so hard to get her sugars under control.

You’d then blame the diet. Most physicians would say, “It’s not that the medicine isn’t working, it’s that the diet isn’t working.” But I was seeing at home what she was eating—exactly what the Diabetes Association and physicians recommend: a low-carb diet—and her sugars were still out of control. That gave me more perspective on my patients. We often assume if patients follow our advice, they’ll get better; if they don’t, they won’t. It’s easy to blame the patient. But I could see that wasn’t always the case. For her and possibly many of my patients, they were following our advice; it just wasn’t working for a lot of people.

Fast forward: I decided to really research whether diabetes is reversible and what role diet plays. After a little under two years of reading articles, books, journals, and research papers, it became clear what the problem was. After I applied that to my wife, within six weeks she was off medicine. I thought, wow—why didn’t I learn this in medical school? These are simple principles, and diabetes is reversible. That led me to create Diabetes 180, a diabetes reversal health coaching program.

Molly Patrick
Wow. Six weeks?

Molly Patrick
That’s such a cool story. It was really close to your heart. What made you put two and two together—that maybe diabetes could be reversed through lifestyle and diet? Because if what you were taught wasn’t working, what gave you the nudge to try a different approach?

Lewis Bertus, PA-C
I had another advantage: I grew up in the Seventh-day Adventist Church. Many people are familiar with their health leanings. We promote a holistic approach to life—healing mind, body, and spirit through natural, holistic methods and healthy living.

Molly Patrick
Okay.

Molly Patrick
Yeah.

Molly Patrick
Right.

Lewis Bertus, PA-C
I always understood that food is medicine, and if you apply the right foods to the right conditions, you can heal and reverse them. I had read stories and testimonials of people doing this, including with diabetes. Even while I was learning the medical side, I knew there was a dietary approach. Many Seventh-day Adventists are plant-based—vegan or vegetarian. I had been vegetarian for a while, and so had my wife. We knew plant-based eating had benefits; we just didn’t know how to put it together to reverse diabetes until we looked closely at the science.

Molly Patrick
Okay, interesting. There have been a lot of long-term studies with Seventh-day Adventists because it’s a large group with similar dietary patterns. That’s how I first learned about them—through those health studies. Some really cool research.

Lewis Bertus, PA-C
Absolutely.

Molly Patrick
Is that something you got into as an adult, or did your parents raise you that way?

Lewis Bertus, PA-C
My parents didn’t raise me vegetarian. I’m Haitian American, and many Haitian Americans in the Seventh-day Adventist Church still eat meat—mainly chicken. We don’t eat what we call unclean foods like pork and shrimp, the “scavengers.” But I grew up with chicken, and occasionally burgers and steak. It wasn’t until college, when I became more health conscious, that I started leaning more plant-based.

Molly Patrick
Okay, interesting. So you had that background to draw from, and then you put it together with the fact that your wife wasn’t getting better with the prescribed medications and diabetes diet. You did research for a couple years, dove into the science, and thought there might be a different way. Did you and your wife make the changes together in your kitchen?

Lewis Bertus, PA-C
Yes, we did it together. Within Adventism there are different types of vegan and vegetarian eating. Some exclude all meat and dairy, some include dairy and maybe fish, and some include eggs. We tried them all—low-carb, keto. When I finally got to the evidence-based approach, my wife was actually on keto. It was the only thing keeping her blood sugars controlled, and you can imagine what a sacrifice that was for her after trying to be plant-based for so long.

It was frustrating for me because I knew this wasn’t the way. Her sugars were normal, but it was causing long-term damage. Her liver enzymes were elevated, and her cholesterol increased. Now she was at risk for heart disease even though her sugars were controlled. When we made the switch, we did it together, and it made things much easier. My heart goes out to people trying to change their diet when a family member—especially a spouse—isn’t on board. When your spouse is on board, it makes a world of difference.

Molly Patrick
I’ve seen that in our community. A lot of people do this alone, and there’s a unique challenge there. People have to be really motivated, and that often comes from a health scare. That’s usually what it takes.

Lewis Bertus, PA-C
Yes. Often it’s not until they’re at the point of dialysis, or they’re told they have nonalcoholic fatty liver disease, or they start noticing vision changes. Diabetes is the leading cause of blindness and limb amputations. It’s not until people get really sick that they get motivated enough to tune out the noise and do what they need to do.

Molly Patrick
Okay, so now you’ve changed course. You coach people to reverse diabetes, which is amazing. What do you know now that you wish you’d known when your wife was diagnosed—or even before?

Lewis Bertus, PA-C
I wish everyone knew this: diabetes is not caused by sugar. High blood sugar is a symptom, not the cause. I wish medical school had emphasized the connection between fat and insulin resistance.

Molly Patrick
Okay.

Lewis Bertus, PA-C
Understanding the science of how diabetes really works is key. When we educate the public, they can see the importance of limiting dietary fat—especially saturated fat, which is mainly found in animal products.

Molly Patrick
Can you dive into that science a bit?

Lewis Bertus, PA-C
Sure. This isn’t new—nearly 100 years old. In the late 1920s, experiments showed the effect of fat on insulin resistance and blood sugar. One of the oldest experiments, by Dr. Sweeney, put young men on different diets: high fat, high protein, and high carbohydrate. The high-carb diet included foods we’re told to avoid—sugar, white flour, white bread, white rice—and they ate nothing but that for two days. After two days, those on the high-fat diet had the highest blood sugar—double that of the high-carb group. These were non-diabetic individuals, but after two days on a high-fat diet, they essentially turned diabetic. In the 1920s, we already understood there was a fat connection.

Fast forward to today: we now understand more of the mechanism thanks to tools like MRI scans that show what happens inside muscle cells when blood is infused with fat. The fat gets inside the cells and blocks insulin from working, disrupting receptors at the cell surface and making insulin almost unrecognizable at the “door.”

A simple analogy: insulin is a key that unlocks the cell door to let sugar in. Sugar is like a vampire—it needs an invitation to enter the house. We think sugar is the problem, but the real problem is what’s keeping it outside. It’s insulin’s job to open the door and let sugar in. When insulin is resisted at the door, it’s like the lock is gummed up. What gums up the lock? Fat. The fat we eat—and the fat we store—prevents insulin from working at the door, so sugar stays outside the cell, raising blood sugar. So it’s not sugar’s fault; it’s insulin being resisted by a diet too high in fat, leading to fat stored in muscles and in the liver.

Molly Patrick
That makes sense. Just as a note, we’re talking specifically about type 2 diabetes here, right?

Lewis Bertus, PA-C
Yes, thanks for pointing that out. There are similar mechanisms in type 1 and type 2, but with type 1 the pancreas doesn’t produce insulin, so the door never opens. No matter the carbohydrate intake, sugar can’t get in without insulin. But type 1s can also develop insulin resistance if they eat a high-fat diet. The insulin they inject becomes less effective, so they need higher doses over time—even with stable carb intake. Many type 1s have experienced this.

For both type 1 and type 2, the advice is the same: lower fat intake, ideally to 10–15% of daily calories. If you want a gram target, about 30 grams of total fat per day. As you do this, insulin sensitivity improves—either to your own insulin (type 2) or injected insulin (type 1)—and you need less insulin, which is best long term.

Molly Patrick
Such good information—and so many studies support this. You also saw it firsthand with your wife. Even after a couple years of digging into the science, were you surprised it worked?

Lewis Bertus, PA-C
I wasn’t surprised because I understood the science. If you’re not plant-based and you switch to a plant-based diet, you eliminate a lot of fat immediately, especially animal fats common in Western diets. So it made sense that within weeks you’d see improvements.

One caution for anyone trying this at home: if you’ve been low-carb for a while, in the first days or weeks your sugars may rise. People think, “This isn’t working; my sugars are higher than ever.” Things can get worse before they get better because your body needs time to heal. On a whole-food, plant-based diet, you’re eating more carbs than your body is used to, and it takes time for the fat in your muscles and liver to be burned off. As you stop feeding your body fat, it starts turning over stored fat. It takes time to clean out that “gum” in the lock.

My wife wanted to quit. Her sugars were still in the 400s at first. But I believed in the science. I knew if it makes sense scientifically, it would make sense physiologically. It took about six weeks for her, which may be longer than average because she’d had diabetes for so long.

Molly Patrick
Did her numbers gradually come down during those six weeks, or was it a sudden shift?

Lewis Bertus, PA-C
From what I remember, the first two weeks showed almost no change. Around three weeks, we started seeing more dips toward normal, and then it gradually got better. Occasionally there was a spike out of nowhere, but even those stopped over time. It became gradual, then normal—and stayed normal.

Molly Patrick
I was just talking to someone who switched to a whole-food, plant-based diet to lower high cholesterol. Her next blood test showed her cholesterol went up a little, and her doctor pushed medication. She asked for more time, and on the next test her cholesterol was normal. I’ve heard that can happen—an initial bump—because the body is clearing things out.

Lewis Bertus, PA-C
Exactly. Think logically—where does the fat go? When you switch to a whole-food, plant-based diet, you often lose some weight. As your body burns fat, fatty acid breakdown products spill into the blood, which can temporarily raise cholesterol. It’s temporary. We’re used to instant results and a pill for every ill. But you didn’t develop diabetes, high cholesterol, or high blood pressure overnight. It takes time to return to normal.

I should also address people who are diabetic and already plant-based. If you’re plant-based and still struggling, track your fat intake. Even on a plant-based diet, fat can be high—especially with processed foods, plant butters, oils (even extra-virgin olive oil), and seed oils. These can keep the “lock” gummed up. Measure your fat intake and aim for 10–15% of total calories.

Molly Patrick
Great reminder. “Plant-based” has become a blanket term. At Clean Food Dirty Girl, we focus on whole-food, plant-based—no processed food, including oil. But even then, you can still eat a high-fat diet if you’re eating a lot of olives, nut butters, and nuts. It’s a step in the right direction to avoid processed food, but you still have to be mindful and count fat.

Lewis Bertus, PA-C
Yes—don’t discount plant fats. They still need to be watched, especially for those with insulin resistance. Diabetes isn’t the only insulin-resistant condition; anything within metabolic syndrome can benefit from a low-fat approach.

Molly Patrick
It’s wild how many people suffer from diabetes and its complications—vision loss and amputations can be devastating. Do you have the stats for how many people in the U.S. are type 2 diabetic or prediabetic?

Lewis Bertus, PA-C
One alarming statistic: one in four people has diabetes and doesn’t know it—either prediabetes or full-blown diabetes. Look at four people in a room—one of them has diabetes. It’s getting worse. Everyone knows someone with diabetes, but it’s worse because you might have it and not know it. How often are we checking blood sugar? And even when we do, how many doctors check insulin levels to detect insulin resistance—the root cause? Your blood sugar and A1C could be normal, but your pancreas might be overproducing insulin because of your diet. Years later, suddenly you’re “prediabetic.” In reality, you’ve been on that path for years; it just wasn’t detected because insulin wasn’t checked.

Molly Patrick
Good point. I get yearly labs and A1C, but how do we ask to check insulin resistance? Is that a common test?

Lewis Bertus, PA-C
It’s becoming more common. Endocrinologists often order it, and most doctors should know about it. You can ask to add a fasting insulin test to your annual labs. It’s not expensive to include.

Molly Patrick
Great tip. Now that you’re coaching, what have you seen with your clients?

Lewis Bertus, PA-C
One surprising thing is how many people tell me in the first consultation, “I will never be plant-based.” I say, “Just give it a try—what do you have to lose?” The transformation by 90 days—usually much sooner—is incredible. They embrace the changes and never want to go back. They’re surprised by the variety of food.

I’m in North Carolina—good country cooking—people love their fatback and meat. Some come to me at the point of desperation. One client was on the verge of dialysis. Her nephrologist said she’d likely start dialysis within three months and told her there was nothing she could do. She initially declined a consultation with me because she wasn’t ready to change her diet. Later she called back—her doctor had scared her. She didn’t want dialysis. We started.

Three months later, she returned to the nephrologist. Her labs showed her kidney function went up. They asked what she did and even brought in another doctor; they had never seen someone’s kidney function improve at that stage. When she explained the diet, they didn’t believe her. She felt they were almost frustrated—as if they’d lost a customer.

Molly Patrick
That’s so sad. How is she doing now?

Lewis Bertus, PA-C
She’s loving the diet. Often the people most resistant at first become the biggest proponents—showing off their latest whole-food, plant-based meals.

Molly Patrick
That must be so satisfying—truly life-changing. There’s often a knee-jerk “I could never” at first, even when someone’s in bad shape. But once they start, the food is good, they feel good, and their body heals. It’s like, why would I ever go back?

Lewis Bertus, PA-C
Exactly. You never realize how sick you were until you get healthy. Nothing tastes as good as healthy feels.

Molly Patrick
I’ve heard similar stories where doctors think test results must be wrong and retest because improvements “don’t happen.” Even with glaucoma—someone improved and doctors were baffled. I always say, tell them it’s whole-food, plant-based!

Lewis Bertus, PA-C
It’s a shame we don’t know this. Studies show physicians often know less about nutrition than the average person on the street. Another patient of mine had his A1C drop to normal. His doctor assumed the medications finally worked. The patient said, “I haven’t taken those medicines in months.” The doctor said, “How is that possible? Maybe you were never diabetic.” Then the doctor didn’t want to continue monitoring A1C—my patient had to convince the doctor to keep checking it.

It’s sad how little nutrition we learn in training, especially since most of what we treat is diet-related. You’d think a healthy diet would be one of the first things taught. It’s often the last.

Molly Patrick
It has to start from the ground up, with patients informing doctors. Even after health improvements—reversing prediabetes, losing weight, lowering cholesterol—people are still afraid of carbs. That fear is so ingrained. Can you talk about carbs? People hear, “Carbs are bad,” over and over.

Lewis Bertus, PA-C
That’s a big one. Even after hearing this, people will encounter dozens of messages saying carbs are bad—ads, social media, fitness circles. For every one person saying “it’s not the carbs,” nine say it is.

I remind people to consider the source. Every major health institution agrees that the main problem in insulin resistance and diabetes is fat—especially saturated fat. “Low-fat” isn’t a fad; it’s science. Unfortunately, “low-carb” is a fad that helps sell meat, dairy, and eggs. Fads aren’t based on science; they’re driven by what sells. Ask yourself: What makes more money—fruits and vegetables, or meat and dairy? Meat and dairy are multi-billion-dollar industries with influence to convince the public to eat more, not less.

That said, this doesn’t mean go drink cola. We’re talking whole-food, plant-based—not refined, highly processed carbs. For perspective: overeating calories of anything leads to weight gain. If you overeat sugar, studies show liver fat can increase by about 30%. But if you overeat the same number of calories from fat, liver fat increases by over 50%. So while processed sugar is fattening, fat is more fattening.

Also, per gram, carbohydrates and protein have 4 calories, but fat has 9 calories. Why are we still thinking carbs are more fattening than fat?

Molly Patrick
Right. When you look at the numbers, it’s obvious. And there are complex carbohydrates—veggies, beans, blueberries—and simple carbs that don’t do your body any favors. There are also different kinds of fats. Ultimately it comes down to being mindful about what you’re putting in your mouth. If you zoom out beyond influencers and ads, eating a diet filled with whole plant foods that haven’t been messed with too much makes sense. The body responds well to that.

Lewis Bertus, PA-C
Yes. A visual example: money. If you’re allowed to carry only a certain weight of money in your pocket, would you choose coins or dollar bills? You’d choose dollars—they carry more value while weighing less. Dollars are your complex carbs—steel-cut oats—while coins are your refined carbs—quick oats or boxed cereals. Refined carbs are “heavier” in the sense that they rack up calories quickly; they’re stripped of fiber and nutrients and are calorie-dense, leading to weight gain and blood sugar spikes. Complex carbs are rich in nutrients, fiber, and phytochemicals—adding value to your health while keeping calorie density low. Fill your “pockets” with dollars, not coins.

Molly Patrick
That’s a great analogy.

Molly Patrick
If someone’s hearing this for the first time and wants to try it, what does a day of eating look like—breakfast, lunch, and dinner? What do you have your clients eat?

Lewis Bertus, PA-C
Let’s rethink breakfast. Traditional breakfasts—eggs, sausage—are often fatty. Instead, focus on whole complex carbs like oatmeal. Blueberries are great to add; they act as “starch blockers” that can help with carbohydrate digestion. If you love eggs, try a lower-fat option like scrambled tofu—seasoned well, it can taste just like eggs. Scrambled tofu with sweet potatoes is a great breakfast.

For lunch, lunch and dinner are interchangeable. One benefit is you don’t need to carb count. A bean-based burrito is quick and satisfying. Salads can be quick and easy.

For dinner, soups are great. I love rice and beans—brown rice with beans, maybe with sweet potatoes or ripe plantains. I love quinoa. Stir-fries are quick on the stove at night. A big fruit bowl can be breakfast, lunch, or dinner. Once you address the root cause—remove the “gum” from the lock—your complex carbs can get into the cells all day long.

Molly Patrick
Wonderful—and there are so many options. Honestly, I eat way more variety now than I ever did.

Lewis Bertus, PA-C
Same. There’s so much to discover—like the world of mushrooms. If you’re craving chicken, try oyster mushrooms and season them like chicken; the texture is similar. For a “steak,” try portobello or lion’s mane—slice and sear them, season them well. If you don’t like mushrooms, you probably haven’t seasoned or prepared the right variety. Asian markets are great for finding different mushrooms.

Jackfruit is another one people aren’t familiar with—barbecue jackfruit with a good sauce on whole-grain bread can feel like a pulled-chicken sandwich. My advice: season your vegetables like you would your meat. Don’t disrespect the vegetables—they like seasoning!

Molly Patrick
Yes! And the same diet that helps diabetes helps heart disease, supports a healthy gut, and reduces inflammation. It’s a positive domino effect.

Lewis Bertus, PA-C
I love when people say, “I didn’t know you’d fix my blood pressure, cholesterol, and weight too—I just came for diabetes!” There’s no greater feeling. I still work as a physician assistant, but I’ll never stop health coaching because it gives me time to educate, motivate, inspire, and hold people’s hands through the hard parts—turning knowing into doing.

Molly Patrick
Exactly. There’s a lot of information out there; understanding it is one thing, putting it into action is another. The learning part can be interesting, but the doing can be daunting. Having someone guide you is so valuable. Do you have clients outside North Carolina?

Lewis Bertus, PA-C
Yes. That’s the beauty of the virtual world and health coaching. Health coaching doesn’t replace your doctors—I’m not acting as your physician but as your coach—so I can work with anyone around the world. I’ve even had clients overseas. If you have Wi-Fi, we can meet.

Molly Patrick
Awesome. I’ll put your info in the show notes so people can connect. What’s your website?

Lewis Bertus, PA-C
It’s my first and last name: lewisbertus.com. On social media, search “Diabetes 180” with my name and you’ll find me.

Molly Patrick
Perfect. Thank you for the work you’re doing. We’re saturated with messages that are the opposite of what we’re talking about, so thanks for being a voice for good information.

Lewis Bertus, PA-C
Thank you. Sometimes it makes me want to pull my hair out.

Molly Patrick
There’s a lot working against it, but it creates a ripple effect. People in our community transform their health, then their cousin, sister, or mom notices and pays attention. Every person you help has the potential to help many more.

Lewis Bertus, PA-C
Well said. I thank God for the opportunity. It’s humbling to be part of something so big.

Molly Patrick
Thank you for sharing your expertise and knowledge with us. I really enjoyed talking with you, Lewis.

Lewis Bertus, PA-C
Thank you for having me.