Dr. Lee (smiling) "Starting today, we're going to live without meat — and live more healthily."

Students (in unison) "Whaaaat???"

Woman in her 30s "But protein comes from meat, doesn't it?"

Dr. Lee (eyes sparkling) "From today on, I'm going to upgrade that piece of common knowledge for you."

Grace "At 80 years old — can my brain really still get better?"

Dr. Lee "Brain cells stay alive to the very end. The plant-based ketogenic diet is what wakes them up."

Dr. Lee "And these are the topics we'll cover."

Zoe (inner voice) "Whoa… this might actually be fun?"

Emily (inner voice) "I have to learn this."

Susan (inner voice) "There's something to this."

Preface

I had set the title of this book — The Natural Healing Principles of the Plant-Based Ketogenic Diet — first, written a draft, and asked some interested readers for their feedback. One of them wrote back:

Doctor, as far as I know, very few people understand the ketogenic diet as well as you do. But people these days don't read books much — and certainly not boring ones. It might help to cut the scientific studies, papers, tables, and graphs in half. Instead, why not include more of the stories you've experienced personally? Stories make things much easier to understand.

Hearing this, I had to admit she had a point. After receiving my Ph.D. in 2017, I had ambitiously written a specialized book called The Healing Science of Vegetarianism — nearly 600 pages long. Even I didn't feel like reading it. By contrast, Vegetarian Stories, which I had written more than 20 years ago, before entering graduate school, is still fun to pick up; I find myself laughing as I read it.

I do take pride in The Healing Science of Vegetarianism — it pulls together specialized research journals into a body of evidence-based work on the health benefits of a vegetarian diet. But what good is it if the public never reads it? So I changed my approach and decided to rewrite the book in a conversational, story-telling style. I'd share, honestly, the various experiences I had lived through over the years, while presenting the technical content as plainly as if I were chatting with a friend. I hope this book reads more enjoyably for you.

Cast of Characters

Dr. Lee A vegetarian-nutrition scholar and activist. He originally taught chemistry and biology to college-prep students at a private academy. While doing vegetarian advocacy work, he entered a graduate program in food and nutrition and earned his doctorate. After his Ph.D., he founded the Korea Vegetarian Nutrition Research Institute and began offering vegetarian-nutrition lectures. He lives alone in a fifth-floor rooftop room in Hu-am-dong, at the foot of Namsan, and runs his institute, classroom, and office on the second floor of a building near Sookmyung Women's University subway station.

Susan A middle-aged woman, quietly wealthy — she owns several small buildings in Seoul. Five years ago she was diagnosed with kidney cancer and had one kidney removed. Her body has been chronically swollen ever since, and she has been working to heal naturally by attending various health lectures and putting them into practice.

Zoe A young computer-graphics designer who has been a vegetarian for three years. She came to vegetarianism through her love of dogs. Feeling that she needed proper nutritional knowledge, she signed up for the lectures.

Emily A determined woman in her late 30s who loves cooking healthy, mostly organic meals for her two children — a kindergartener and a second-grader. After taking vegetarian-nutrition classes, she transferred into a nutrition department and is now working toward a registered dietitian credential.

Grace Has been a strict vegetarian her entire life — from birth until now, at 83. She trained as a pharmacist in Korea, then immigrated to the United States, where she worked as a clinical dietitian in a hospital for 30 years before retiring. She returned to Korea with her husband to share healthy nutrition information, but in 30 years Korea had changed beyond recognition. Her husband passed away a few years ago, and she has continued her nutrition studies and vegetarian practice on her own.

Period 0. Before the First Class

Bright sunlight streams through the wall of glass that fills one side of the room. A crisp morning breeze, drifting down from the green forest of Namsan, slips through the 40-year-old window frames and fills the office. The potted palm trees seem to nod a cheerful good-morning. The wall clock reads 8:50 a.m. Then, from the hallway, voices approach, and the wooden door creaks open.

Zoe "Doctor — you like green tea, don't you? I brought some for you."

Dr. Lee "Oh, thank you. I'll get the hot water."

I put the kettle on. About ten minutes later the water boiled. We steeped the tea, poured it into cups, and sipped. The fragrance of the green tea filled the room. Zoe, in her mid-twenties, is a computer designer at a marketing company located in Samgakji, just nearby. She had been keeping a cat when, one day, she suddenly recognized that the cat she was sharing emotions and connection with was the same kind of being as the meat she was eating. Soon after, she switched to a vegetarian diet.

As we breathed in the green-tea scent, the door opened again. It was Susan, the homemaker who had taken last week's class.

Susan "Doctor — because of you, I almost fell flat on my face!"

The Gyeongsang-province woman I was meeting again after a week was beaming, half-scolding me with delight. I run the vegetarian-nutrition lectures from a 50-square-meter office on the second floor of a building tucked into the slopes of Namsan in Yongsan, Seoul. In the mornings, with clean air pouring in and sunshine flooding the room, I teach weekend and weekday classes. As the Gyeongsang woman went on with her story, I realized once again the remarkable natural-healing power of the plant-based ketogenic diet.

Susan "Doctor, the truth is, five years ago they found kidney cancer in me, and I had one kidney removed, you see. So with only one kidney to filter waste, my body's been swollen all the time. After the surgery I went to Japan and got stem-cell treatments — twice. Fifty million won a session, so about a hundred million won total."

"After the stem-cell treatments I felt a bit better, but the swelling was still there. Then last week — after our first phone call, where you told me what to do — I went home, cut down on rice, and increased the seoritae black soybeans in my meals. I had a meal of nuts, cucumbers, and bell peppers. And the swelling started coming down rapidly. After my kidney surgery my whole body had been swollen — even my feet, so I'd always worn shoes one size too big. Then I followed your plant-based ketogenic plan, and the swelling in my feet went down, and my shoes turned all loose on me. That's why I almost tripped! Doctor, thank you so much."

I just smiled and listened as she spoke with so much excitement, thinking to myself:

Dr. Lee (inner voice) Last week I'd thought she was a slightly heavy-set person — but it turned out she'd been swollen because her body wasn't excreting waste properly. Today, when she walked through the door, her face looked brighter and slimmer, and now I see why.

While I was thinking, the wooden door opened again.

Emily "Doctor — hi! I'm not late, am I? My husband dropped me off. This is lunch — I made it. It's vegetarian. I packed enough for all of us today."

Dr. Lee "Oh! You even prepared lunch? Thank you so much."

Figure 1-1. The plant-based ketogenic diet classroom.

Emily is a homemaker in her late 30s, with a son in daycare and a daughter in second grade. Before her children were born she worked as a financial coordinator, doing personal asset-management consulting. She has been a vegetarian for ten years and loves preparing healthy, mostly organic meals for her children. After diligently attending the vegetarian-nutrition lectures, she came to recognize the importance of nutrition; she is now working toward a registered dietitian credential and has transferred into a nutrition department to study in earnest. Even before today's class, she had grasped the concept of the plant-based ketogenic diet and had felt her own body's condition improve when she actually followed it. That experience has only made her more eager.

Dr. Lee "Looks like everyone's here today. Shall we start the class?"

Suddenly the door creaks open and an older woman walks in.

Grace "Hello, Doctor. Do you remember me? I'm Grace."

Dr. Lee "Oh — yes, of course I remember. How have you been? It must take more than an hour to get here from Uijeongbu — how did you make it?"

Grace "Doctor, would it be all right if I sit in today? Not long ago we had a phone call, remember? I followed what you told me — I gave up the wheat-gluten 'meat' and ate seoritae soybeans instead. I cut back on rice, took perilla seeds to a mill to be ground, and ate two spoonfuls of them a day. And the swelling in my face and body that had lingered after my brain surgery — look, it's gone, I've gotten this slim. I worked as a hospital dietitian in the U.S. for 30 years, but it took until now for me to realize that what I'd been taught was wrong. So I've come to learn something new."

Grace finished college in her twenties and emigrated to the United States. Originally a devout Christian in Korea, she had completed pharmacy school and earned her pharmacist's license. She then went to the U.S., earned her clinical-dietitian credential, and worked as a hospital dietitian for 30 years until retirement. She also married in the U.S. After retiring, she and her husband returned to Korea, hoping to bring back advanced American nutrition expertise — but she was unable to find an outlet for her work, and her husband passed away a few years later. While living alone afterward, she fell on a bus and underwent brain surgery. Since then her face had been chronically swollen and her health had not been good. Even so, her genetically robust constitution kept her stable. Some time ago I had sent her a message via KakaoTalk announcing that I was running a nutrition lecture, and she had come, in part, to see what it was like. The previous time I'd seen her, her face and body were swollen and she looked unwell. But today, with her diet changed and the swelling gone, this 83-year-old in a denim jacket — from behind — could pass for a college student in her twenties.

Dr. Lee "Of course you can. Thank you for coming. Everyone — that's all right with you, isn't it?"

Everyone "Yes! Welcome!"

I'd Like to Know What "Plant-Based Ketogenic Diet" Means

Emily "Doctor — what exactly is the plant-based ketogenic diet?"

Dr. Lee "Yes — the plant-based ketogenic diet is plant-based plus ketogenic. 'Plant-based' means we don't eat animals; we eat only plants. Animals are organisms that can move; plants don't move and rely on photosynthesis. Photosynthesis is how an organism, by capturing the energy of light, can synthesize a wide range of nutrients on its own. So you may be wondering, what is the ketogenic part? Words like 'plant-based' and 'animal-based' are everyday vocabulary, but most people don't really know what 'ketogenic' means. Even if it's the first time you're hearing the term, it's a very important word for human health and for the healing of disease, so it's worth understanding well.

"A ketogenic diet is a way of eating that causes the body to produce ketone bodies. Ha — and now you're wondering what ketone bodies are! Think of ketone bodies as nutrients produced by living organisms. We talk about the three macronutrients the body needs in the largest amounts: carbohydrates, proteins, and lipids. From here on, please take lipid and fat to mean the same thing.

"Ketone bodies are now recognized as a 'fourth macronutrient,' alongside the original three. Over the past 20 years or so, many scientists have come to recognize their importance, and several hundred related studies are now being published every year. I'll explain in detail later, but for now, please just hold on to this: lipids travel to the liver, where they are converted into ketone bodies — a fourth fuel used by the brain and the heart muscle."

Emily "A fourth macronutrient? Aren't carbohydrates, proteins, and lipids enough? I've never heard the term ketone body before. What is it, and what is it used for?"

Dr. Lee "Good question. I'll go into detail in later sessions, but in short: ketone bodies are a nutrient form produced when lipids travel to the liver and are converted there. Why are ketones needed? When are they needed? Where are they used? It's natural to wonder. Some unfamiliar substance shows up out of nowhere and announces it's important — of course you have questions. So, before I explain ketone bodies themselves, let me first give you a useful concept.

"First, it helps to know that human energy metabolism comes in two forms — postprandial (post-meal) metabolism and fasting metabolism (Owen et al., 1967)."

Human metabolism comes in two forms — postprandial and fasting

Postprandial metabolism is the energy-generation process that takes place in the cells when nutrients are absorbed from the digestive tract after a meal. Fasting metabolism is the energy-generation process that takes place in the body when we cannot eat — when we go hungry.

Zoe "But there's plenty of food at the supermarket, and restaurants everywhere — why would we go hungry?"

Dr. Lee "It's a fair question. Walk into a supermarket and you'll find a richly stocked variety of foods. Walk down the street and you'll find restaurants lined up everywhere. So we eat easily — three meals a day, plus snacks and drinks in between. But up until the 1960s, in our country, there was something we called the 'spring barley hump,' when many people went hungry. Today Korea is one of the wealthier nations in the world. I bring this up to point out that, on a global average, our country has become wealthy enough that almost no one starves to death."

Zoe "Right — I've heard that there are still many people around the world who suffer from malnutrition or hunger. I once met some volunteers handing out flyers asking for donations to help people going hungry in Africa or in other poor countries. I also saw a photo exhibition about it."

Dr. Lee "Indeed. Even now, in the poorer countries of the developing world, many people go hungry. Roughly one billion people worldwide are nutritionally deficient, and an estimated 30 million die from hunger each year. Until nitrogen fertilizer was widely produced in the 1960s, human history was a history of famine (Smil, 2001). For most of history, most people lived with a constant shortage of food. Once a method to manufacture nitrogen fertilizer was invented, grain production doubled in just 30 years (Erisman et al., 2008; Smil, 2004). Never before in human history had grain production doubled in such a short period. But even today, going hungry through the winter and early spring is a natural occurrence for wild animals. In summer and autumn there is plenty to eat; in winter and early spring, food is scarce."

Emily "Yes — given that there are still hungry people in the world today, it makes sense that wild animals would also go hungry in cold winters when food disappears. It reminds me of the bears that sleep through the winter. Bears can sleep for several months in winter, can't they? But even when they're asleep, they have to keep breathing and maintain their body temperature, so their body must keep producing energy somehow. (Pauses to think.) Ah — so the fasting metabolism you're describing is the energy-generation process that occurs in a hibernating bear. Then what's the difference between postprandial metabolism, which generates energy when we eat, and fasting metabolism, which generates energy when we don't?"

Dr. Lee "That's right — you can think of fasting metabolism as the energy production happening in a hibernating bear that isn't eating. Often the easiest way to understand a phenomenon is by comparing differences. Simply put, postprandial metabolism uses carbohydrates as the primary fuel to produce energy, while fasting metabolism uses lipids as the primary fuel."

Zoe "Since rice and bread are our staple foods, it's easy to see that we use carbohydrates as the main fuel when we eat. But how is it possible to use lipids as fuel when we aren't eating?"

Dr. Lee "That's exactly the heart of what we're going to discuss. How can we use lipids as energy when we aren't eating? And why does the body use lipids as energy in the fasting state? To understand this, we need to grasp the concept of storage efficiency of the nutrients the body holds in reserve."

Lipids have more than 5 times the storage efficiency of carbohydrates

Dr. Lee "Do you know how much energy 1 g of carbohydrate produces?"

Emily "I think I learned this in high school. It's 4 kcal per gram."

Dr. Lee "That's right. When you read a book, talk with a friend, or think about something, your brain uses about 1.5 kcal per minute. So that's roughly what your brain consumes during 2 minutes and 40 seconds of conversation. A minute of leisurely walking uses about 4 kcal. Vigorous exercise uses about 10 kcal per minute. As you said, carbohydrates yield 4 kcal per gram. So you probably also know how much energy 1 g of protein and 1 g of lipid yield?"

Zoe "Of course — protein is the same as carbohydrate, 4 kcal per gram. And lipids yield 9 kcal per gram."

Dr. Lee "Excellent. Correct. Because protein contains nitrogen atoms, it's not well suited for storage as an energy reserve. So you can think of the body's energy-storage forms as essentially two: carbohydrate and lipid. Per unit mass, lipids yield 2.2 times as much energy as carbohydrates. But the lipid advantage doesn't end there. Carbohydrates are stored in the body as glycogen, in the liver and muscles, and for every 1 g of glycogen stored, about 3 g of water must be stored along with it (Kreitzman et al., 1992). For lipids, only about 0.1 g of water is needed per 1 g stored. So if you want to store 4 kcal in carbohydrate form, you need 1 g of carbohydrate plus 3 g of water — 4 g total. To store 9 kcal in lipid form, you need 1 g of lipid plus 0.1 g of water — 1.1 g total. Effectively, carbohydrate stores about 1 kcal per gram of total mass, while lipid stores about 8.1 kcal per gram. In practice, lipids have been reported to provide 5- to 6-fold higher storage efficiency than carbohydrates (Cahill, 1970)."

"In nature, when an animal is moving and active, carrying a heavy load is a survival disadvantage; being light while still able to generate plenty of energy is a clear advantage. That's why any nutrient that the body has taken in but not used — whether it began as carbohydrate or as protein — is ultimately converted into lipid form for storage."

Susan "Carbohydrate or protein can turn into lipid?"

Dr. Lee "Yes. The atoms that make up carbohydrate are three: carbon, hydrogen, and oxygen. Protein is made of those same three plus nitrogen. Lipids are made of the same three as carbohydrate — carbon, hydrogen, and oxygen. Think of LEGO bricks. With the same basic LEGO units you can build a house or a car. Likewise, the same atoms — carbon, hydrogen, oxygen — can be linked in different ways to form either carbohydrate or lipid. And when you remove the nitrogen atom from a protein, what's left can be turned into either carbohydrate or lipid. But if the body is going to store something as an energy reserve, it makes more sense to store it as lipid than as carbohydrate or protein."

Zoe "Wow — amazing. The nutrients that build our bodies and fuel our energy work just like LEGO! I love LEGO, so the topic of the body and ketones is getting more and more fun for me."

Dr. Lee "Ha! I'm glad you're enjoying the class. Truly, understanding our own bodies is a delight — and a wonder."

Emily "Doctor — but you haven't yet told us what a ketone body actually is, why our bodies need to produce them, or what they're made from."

Dr. Lee "True. But it looks like the second period is over. Let's take a 10-minute break and I'll cover those in the third period. For now, it's enough to understand that lipid is the body's main storage form. And it's helpful to know that lipid is stored in four main locations — under the skin, in the liver, in the blood vessels, and in the abdomen. Once that clicks, ketone bodies will be much easier to understand."

Emily "Okay! It's getting really interesting — I can't wait for the next session."

The body's stored carbohydrate is depleted in half a day; its stored lipid can sustain it for 80 days

Dr. Lee "All right, shall we begin the third period? Last time I explained that the main energy reserve in the body isn't carbohydrate but lipid. Lipids have 5 to 6 times the energy-storage efficiency of carbohydrates. That's why carbohydrate is stored as glycogen — about 100 g in the liver and 200–300 g in the muscles. By contrast, about 13.5 kg of lipid is stored. These figures are based on a man who is 175 cm tall and weighs 70 kg (Figure 1-2)."

"About 4 hours after we eat, the carbohydrate supplied by that meal begins to be depleted. The body's stored glycogen is then broken down and released into the bloodstream as glucose. If the fasting state continues for about 18 hours, protein and lipid in the body are converted into carbohydrate form to supply the energy that's needed. At the same time, fat in the subcutaneous adipose cells is broken down into fatty acids and glycerol, which are then used as nutrients."

Stored energy in a 70-kg man:

• Carbohydrate: 0.3–0.4 kg (~1,500 kcal)
• Protein: 6–7 kg (~25,000 kcal)
• Lipid: 13 kg (~125,000 kcal)

Figure 1-2. Comparison of energy reserves in the human body.

Source: Cahill, G. F. (1970). Starvation in man. New England Journal of Medicine, 282(12), 668–675.

Emily "So if we fast for about a day, we use glucose and fatty acids as energy at the same time?"

Dr. Lee "Yes. Postprandially, mostly glucose — a carbohydrate — is used. In the fasting state, both glucose and fatty acids are used. As the fast lengthens, glucose use gradually declines and fatty-acid use rises."

Zoe "But Doctor, I thought the brain can only use glucose."

Dr. Lee "Many people share that misconception. But in fact, the brain can use ketone bodies, in addition to glucose, as a major energy source."

Zoe "The brain can use ketone bodies? But there's no nutrient called 'ketone body' in the foods we eat — there's nothing called ketone body on a nutrition-facts label."

In the fasting state, ketone bodies supply two-thirds of the energy the brain needs

Dr. Lee "Good question. You're right — the foods we eat contain no ready-made ketone bodies. Ketone bodies are a nutrient form made by the liver. I mentioned that fatty acids are used as an energy source in the fasting state. But the brain doesn't allow fatty acids to cross into it. So fatty acids travel to the liver, where they are converted into ketone bodies (Figure 1-3a). Ketone bodies cross the brain's barrier even more readily than glucose does. So after about three days of fasting — that is, with just three days of going without food — about two-thirds of the energy the brain uses is supplied by ketone bodies, with the remaining third coming from glucose (Figure 1-3b).

"Now imagine: winter lasts two or three months. When food runs out, the fat stored in the body travels to the liver, becomes ketone bodies, and supplies two-thirds of the brain's energy. The human brain weighs only about 2% of body weight, but it consumes about 20% of the body's energy and oxygen (Figure 1-4). Newborn babies use as much as 60% of their total oxygen consumption in the brain. That's why the human brain is sometimes called a high-energy-consuming organ. Put another way: without ketone bodies, the human brain could not have evolved as it has. One scientist who has studied ketone bodies extensively put it like this: it was thanks to ketone bodies that Homo sapiens — humanity itself — could come to exist."

Figure 1-3. (a) Conversion of lipids into ketone bodies in the liver. Free fatty acids and glycerol from adipose cells travel to the liver, where they are converted into ketone bodies (β-hydroxybutyrate, acetoacetate, acetone) and glucose, both of which are then delivered to the brain. (b) Energy substrates used by the brain in the postprandial vs. fasting state.

Figure 1-4. Brain oxygen consumption as a percentage of total body oxygen, by species.

Zoe "Amazing — I had no idea infants use 60% of their oxygen on their brain. Something just struck me, though. Humans have larger brains than other animals. And the brain uses ketone bodies as an excellent energy source. So newborn humans should be born with a lot of body fat, shouldn't they?"

Dr. Lee "Ha — that's a sharp observation. And in fact, scientists curious about exactly that have looked into it. They surveyed body-fat percentages at birth across many species, including humans. And it turned out that humans, at 16%, had by far the highest fat percentage at birth (Figure 1-5). Guinea pigs were second at 10.8%, harp seals 10.4%. Baboons and sheep were around 3%; rats and hamsters carried only about 1% of their body weight as fat. The implication is striking: humans are born with much more fat than other animals, and they convert that fat into ketone bodies in plentiful supply, feeding the brain."

Figure 1-5. Body-fat percentage at birth, humans vs. other animals.

Grace "It's hard to deny the implications for the importance of a ketogenic diet — the fact that humans are born with so much more fat than other animals. The point about fasting is also fascinating. But wouldn't fasting for more than a day be harmful to the body? When I was working as a hospital dietitian in the U.S., we structured patients' meal plans to meet specific nutrient requirements."

Dr. Lee "Yes — I'm well aware that many nutritionists and dietitians take great care to ensure no nutrient is in deficit. Modern nutrition is sometimes called 'the nutrition of deficiency.' Its focus is on preventing nutrient shortages, and the recommended intake levels are set quite high. The trouble is that nutrient excess is also a problem. As you know, obesity, diabetes, hypertension, cardiovascular disease, kidney disease, and others are largely caused by excess nutrient intake. There are several reasons for this, but one of them is that the concept of recommended dietary intake is widely misunderstood.

"The recommended dietary intake is not an average. The amount of a nutrient required varies among individuals in a population, and the recommended intake is set not at the average but at a level that meets the requirements of the upper 97.5% of the population (Institute of Medicine, 2006). It's the average plus two standard deviations. So if you eat to meet the recommended dietary intake, 97.5% of people will always be in a state of nutrient excess. I'll discuss this in more detail another time. For today, please hold on to two ideas: ketone bodies are a nutrient form produced when fat travels to the liver, and in the fasting state about two-thirds of the brain's energy is supplied by ketone bodies."

A ketogenic diet is fasting while still eating

Dr. Lee "Ketone bodies are used heavily by the brain, but they're also used in places like the heart muscle. So ketone bodies can strengthen heart cells and produce favorable outcomes for heart disease. As we'll see, there are many health benefits."

Susan "Ketone bodies are good for the heart? My husband has a heart condition I've been worried about. If ketone bodies help, I'd love to hear more — how exactly do they help keep the heart healthy?"

Susan "But it would be hard to keep skipping meals. I'd get hungry, and I have to live my daily life."

Dr. Lee "Right. That's exactly why the ketogenic diet concept exists. Ketones are produced when carbohydrate intake drops. When there's a lot of carbohydrate in the bloodstream, insulin is released and ketone-body production is suppressed. So if we lower the carbohydrate content of our food and raise the lipid proportion, the body interprets this as if we were fasting and starts producing ketone bodies. In other words, a ketogenic diet is fasting while still eating."

Grace "If the ketogenic diet is that effective, there must be quite a bit of research on it."

Dr. Lee "Good point. According to a study that surveyed the literature, only 20 papers per year were published on ketogenic-diet research in 2012 (Figure 1-6). By 2018, that had risen to 50, and by 2021 to 96. More striking still, papers that cited ketogenic-diet research — even if they weren't directly studying it — grew from 22 in 2012 to 281 in 2014 (a more than 10-fold increase in two years), to 2,057 in 2019, and to 4,753 in 2021."

Figure 1-6. (a) Annual ketogenic-diet research papers, 2012–2021. (b) Annual papers citing ketogenic-diet research, 2012–2021.

Grace "Astonishing. From 22 to 4,753 citations in just ten years between 2012 and 2021 — really, the volume of research must be enormous."

Zoe "If there are over a hundred new papers a year on the ketogenic diet, the effects must be well grounded. I'd love to try a ketogenic diet myself. But — as you know, Doctor — I'm a vegetarian. I can't eat animals. I'd love to be able to do a ketogenic diet from plants alone."

Dr. Lee "Ha — an essential question. I'd love to answer right now, but it looks like the third period is just about over. I'll cover the details in the fourth period."

Zoe (eyes wide with delight) "Yes! Thank you."

Everyone's eyes are sparkling as they take notes intently.

References