CHAPTER 2

MISUNDERSTANDING HOW YOUR METABOLISM WORKS

One of the most amazing things about your body is the way your metabolism works. It doesn’t necessarily operate by speed—it operates by efficiency or inefficiency. An efficient metabolism has the ability to extract energy from whatever substance is available for the job at hand. For example, your metabolism can create energy from the fat stores in your body, the calories on your plate of food, the glycogen stores inside your liver and muscle cells, the glucose in your bloodstream, and the ketone bodies your liver makes in the absence of glucose. When you are metabolically free, your metabolism can use any of these methods without you even noticing.

If we examine the lifestyle of our hunter-gatherer ancestors, we find evidence that being metabolically flexible kept people from going extinct. Our ancestors didn’t know where their next meal was coming from (or when they’d get it), so their metabolism became fine-tuned to use whatever was available for energy. Our metabolism is still hardwired this way.

Unfortunately, only 7 percent of people in the United States have a healthy, flexible metabolism in the way I just described. As I referenced in the Introduction, 93 percent of people in the United States are metabolically handcuffed. Their metabolism is only efficient at using one of the available energy methods: glucose (sugar). There’s nothing wrong with using glucose as an energy source, unless it’s your only energy source.

In this chapter you’ll learn some of the incredible healing benefits of a healthy metabolism, such as regenerating the neurons in your brain or repairing your gut microbiome. I’ll also share some of the conditions metabolic flexibility works best for, such as breaking weight-loss resistance, helping your body detoxify, and even preventing cancer. Once you understand the science of how your metabolism works, it becomes so much easier to become metabolically healthy.

The Five Healing Benefits of a Flexible Metabolism

When you’re metabolically flexible, your body has multiple ways to generate energy and burn fat. In contrast, someone who is metabolically restricted has far fewer options available. Earlier in the book, I shared some scary statistics on cancer, heart disease, diabetes, and many more chronic health conditions. There are five major healing benefits of a flexible metabolism that can help you avoid becoming one of those statistics:

1. creating adaptation through hormetic stress
2. alternating between the repair pathway (autophagy) and growth pathway (mTOR)
3. supporting your mitochondria
4. regenerating neurons in your brain
5. repairing the gut microbiome by creating biodiversity

Let’s go through them, one by one.

1. Creating Adaptation through Hormetic Stress

One of the most important principles I have learned about health is called hormesis. It will change the way you think about health. Hormesis is defined as a phenomenon in which a harmful substance gives stimulating and beneficial effects to living organisms when the quantity of the harmful substance is small.¹

Figure 2. How hormesis works.

Exercise is the easiest example of how hormesis works. Let’s say you’ve been sedentary for 10 years, and you hear about the benefits of CrossFit. CrossFit is a 60-minute, high-intensity workout often involving Olympic lifts, burst training, and other functional modalities. If you decide that your first workout back into the world of fitness will be a CrossFit one, your body will have a hard time adapting to this stress, you’ll be sore for days, and you may even hurt yourself. You’d have done too much and fallen out of your hormetic zone. However, if you instead did a 45-minute walk and some push-ups, squats, and planks, your body most likely could adapt to this light stress, you’d stay within your hormetic zone, and you’d grow stronger and healthier. You’d have found your sweet spot! Over time the goal is to create a higher hormetic ceiling, so you can apply more stressors and stay within the zone of benefits.

Fasting and ketosis are another example. Yes, fasting stresses your body, but it’s only a bad stress when you don’t properly adapt to the stress. Imagine I’m holding two cups of water. One cup is filled to the brim, while the other is only a quarter full. If I shake both cups with the same intensity—representing stress—the cup that’s full will spill water everywhere, symbolizing the onset of symptoms. On the other hand, the cup that’s only a quarter full won’t spill, even if shaken more vigorously. This illustrates the difference between someone whose stress capacity is maxed out versus someone with less accumulated stress. The person whose cup is filled to the top has a low hormetic ceiling, meaning they can tolerate less stress before symptoms appear. Conversely, the person with the quarter-full cup has a higher hormetic ceiling, allowing them to handle more stress without negative effects. This also explains why some people feel better during fasting, while others do not. When you stay in your hormetic zone, you achieve incredible results.

2. Alternating between the Repair Pathway (Autophagy) and Growth Pathway (mTOR)

Cells are like groceries: When they expire, they need to be thrown out—up to 330 billion of them every day!² Yet sometimes we have cells within our body that begin to dysfunction, and they stick around. Because they refuse to die, scientists call them senescent cells. I call them zombie cells. As they build up in our body, studies suggest they promote aging and the conditions associated with it, such as osteoporosis and Alzheimer’s disease.^{3, 4, 5}

Zombie cells start out normal but then encounter stress, such as damage to their DNA or a viral infection. At that point, a cell can choose to die or become a zombie, basically entering a state of suspended animation. The problem is that zombie cells release chemicals that can harm nearby normal cells. That’s where the trouble starts.

Researchers have also shown that transplanting zombie cells into young mice basically made them act older: their maximum walking speed slowed down, and their muscle strength and endurance decreased.⁶ Tests revealed that the implanted cells converted other cells to zombie status.

One of the best ways to kill off these zombie cells is a process called autophagy.

Autophagy literally means “eat thyself,” and it cleans up damaged cells. Think of the groceries in your refrigerator. What would happen if you allowed them to expire, and instead of throwing the expired food in the trash, you pushed them toward the back of the fridge? You’d create a toxic environment! Mold and bacteria would grow, and many other disgusting processes would occur. Well, your body is just like your refrigerator, in that its cells, fats, and proteins all have expiration dates. If you aren’t intentionally “taking out the trash” within your body, this toxic buildup can lead to diseases like cancer and Alzheimer’s. Fasting helps your body get rid of these expired products, because it triggers the process of autophagy, which breaks down and recycles dysfunctional proteins and cellular debris.

The opposite of autophagy is a pathway called mTOR, which is short for mechanistic target of rapamycin. This pathway signals growth—it is anabolic. (Think of bodybuilders; they get a ton of mTOR.) This pathway can be healing in spurts, but it can lead to problems if you’re in a constant growth state, such as the duplication of these zombie cells. There’s an art to balancing autophagy and mTOR, and this is the focus of your 30-Day Metabolic Freedom Reset. As you’ll see in the pages ahead, when used as part of the Metabolic Freedom lifestyle, intermittent, deliberate fasting can be an easy way to clean out your reserves of glucose, burn ketones, lose weight, and feel great.

3. Supporting Your Mitochondria

The mitochondria are so important that the cells most critical for survival (in terms of energy production needs)—the cells required to stay alive and alert—have the most of them. According to some estimates, each heart muscle cell contains between 5,000 and 8,000 mitochondria, and each neuron can have up to two million!

Mitochondria are also central in retinal cell function and survival. Retinal neurons have high energy requirements, since large amounts of adenosine triphosphate (ATP) are needed to generate membrane potentials and power membrane pumps. Think of ATP as the energy currency created by the mitochondria. In photoreceptors, the number can be quite high as well, with estimates suggesting thousands of mitochondria per cell. The exact number can vary, but it’s not uncommon for a single retinal cell, especially a cone photoreceptor, to contain several hundred to a few thousand mitochondria.⁷ Compare this to other cells, which have hundreds to a few thousand per cell.

This all makes sense from a survival standpoint. The brain and eyes are required to think and see efficiently so you can capture food for survival or run away from a predator to stay alive. The name of the game is survival!

TEN FASCINATING FACTS ABOUT MITOCHONDRIA

1. You get all of your mitochondria exclusively from your mother.
2. The cells that are most metabolically active, and needed for survival, have the highest concentration of mitochondria.
3. The mitochondria fuse together and communicate (adrenals talk to the brain, etc.). This means your mitochondria from various cells communicate with each other.
4. They produce 95 percent of your body’s energy.
5. By age 70, we lose an estimated 56 to 70 percent of mitochondria.
6. Every cell has mitochondria except red blood cells. Red blood cells transport oxygen throughout the body. If they had mitochondria, they would consume some of that oxygen, reducing delivery efficiency to tissues.
7. In one aspect, mitochondria are technically alien organisms inside our bodies. They possess their own DNA (called mtDNA), giving them an independent genome. They operate much like bacteria, but the kind of bacteria working in harmony with our cells in a mutually beneficial symbiotic relationship.
8. The inner mitochondrial membrane contains an unusually high percentage (greater than 70 percent) of proteins, which are involved in oxidative phosphorylation as well as in the transport of metabolites (e.g., pyruvate and fatty acids) between the cytosol (the fluid inside the cell) and mitochondria. Oxidative phosphorylation is the process in which cells produce energy in the mitochondria by using oxygen to convert food into ATP, the energy currency of the cell.
9. The two primary fuels for the mitochondria are minerals and amino acids. The body makes amino acids but not minerals. All these minerals need to come from food sources.
10. There are only two antioxidants the mitochondria can use: glutathione and melatonin.

The mitochondria are much more than “mindless energy factories.” Yes, it is important for them to receive energy in the form of glucose, fatty acids, and amino acids, and to produce ATP, but the mitochondria are also highly intelligent. For example, they act like a surveillance system, looking to identify threats.

Cellular threats come in the form of three key areas:

1. mental/emotional
2. physical
3. chemical

The number one priority for the human body is survival. When your “stress bucket” is full, the mitochondria strategically produce less energy, all for the sake of survival. This is called the cell danger response (CDR). The CDR is the evolutionarily conserved metabolic response that protects cells and hosts from harm. It’s triggered by encounters with chemical, physical, or biological threats that exceed the cellular capacity for homeostasis. The resulting metabolic mismatch between available resources and functional capacity produces a cascade of changes in cellular function.

When the CDR persists abnormally, whole body metabolism and the gut microbiome are disturbed, the collective performance of multiple organ systems is impaired, behavior is changed, and chronic disease results. Metabolic memory of past stress encounters is stored in the form of altered mitochondrial and cellular macromolecule content, resulting in an increase in functional reserve capacity through a process known as mitocellular hormesis.⁸ In simple terms, metabolic memory means that your cells and mitochondria remember past stress, which changes how they function. This memory helps them build up a stronger ability to handle future stress, a process called mitocellular hormesis.

As you can see, having a flexible metabolism that supports your mitochondria is a major health benefit.

4. Regenerating Neurons in Your Brain

Your brain also thrives when you are metabolically flexible. Your neurons—the messengers of your brain that communicate every second—get damaged from excess sugar. When you lower glucose levels in the body with ketosis and fasting, you begin to repair these neurons, allowing information to move efficiently from one neuron to the next. This means less brain fog and more mental clarity and energy.

Your brain consists of between 86 and 100 billion neurons, which are the specialized cells that “do the thinking” and create tiny electrical charges. In addition, there are about an equal number of glial cells that maintain homeostasis, form the fatty myelin insulation around the wire-like dendrites that connect the neurons (yet another example of the vital importance of fat), and provide support and protection for neurons.

The fuels that power your brain are glucose, ketones, and oxygen, via the bloodstream. Like other cells in the body, the respiration process in the brain cells creates waste or by-products, including carbon dioxide, water, ammonia, and various types of proteins. In the brain, two proteins in particular are produced: amyloid beta and tau. Amyloid beta is what forms the plaques found in the brains of Alzheimer’s patients. Tau, which resembles sets of parallel railroad tracks, can be damaged or “tangled” and cause mitochondrial dysfunction. Tangles of tau are the hallmark of many neurodegenerative diseases. In certain diseases, neurons and/or other brain and nerve cells can have a problem with transporting glucose into the cell and essentially starve and die. Ketones can be taken up by neurons that cannot use glucose.

5. Repairing the Gut Microbiome by Creating Biodiversity

Research has shown that fasting heals the gut. Many of the positive changes that occur in your gut microbiome come to a screeching halt once you eat. We usually think of food as giving us energy, but digesting the food we eat actually requires energy. When we eat food, it takes massive amounts of energy to process that food. It is estimated that after a heavy meal, 65 percent of the body’s energy must be directed to the digestive organs. During fasting, we rest our system from the constant onslaught of food. We redirect our energy toward healing and recuperation. Our body can detox, repair cells, and eliminate foreign toxins and natural metabolic wastes.

Chewing food and allowing the body to take macronutrients and assimilate them into micronutrients for distribution is a big task. One of my favorite benefits of fasting is a process I call energy diversion. When you’re in a fasted state, your metabolism diverts resources that would have been used for digestion and directs them toward areas of your body that need healing.

The gut bacteria Akkermansia has also been shown to have anti-obesity protective effects, and many companies are now adding it to their probiotics. While the research on whether or not these probiotics can raise this useful bacteria is questionable, studies have shown that fasting increases an abundance of Akkermansia.⁹ Researchers found that intermittent fasting positively influences the gut microbiome by increasing the diversity of beneficial bacteria while reducing harmful ones. These changes in the gut microbiota were also associated with improvements in blood lipid profiles, suggesting that IF can contribute to better overall metabolic health. The findings highlight the potential of IF as a noninvasive strategy to modulate gut health and improve cardiovascular risk factors.¹⁰

Five Conditions Metabolic Freedom Supports

Now that you understand how these principles heal your body, let’s look at which specific conditions they work best for. There are five distinct times when flexing in and out of fat burning versus sugar burning will be the answer to your health symptoms. Metabolic freedom can support you in:

1. breaking weight-loss resistance
2. preventing cancer
3. slowing the aging process
4. reversing autoimmune conditions
5. detoxifying your body

Let’s explore each one of these now.

1. Breaking Weight-Loss Resistance

Survival is the number one priority for your innate intelligence. When you eat, which raises your blood glucose levels, your cells will burn energy from the food you ingested. Anything in excess goes into your glycogen stores, and then is stored in body fat. We’ll call this the fed state. When you fast, you turn on a switch that allows your body to tap into your glycogen stores and body fat. We’ll call this the fasted state.

When you’re looking for lasting weight loss, it’s important to train your body to be really efficient at both of these processes. If you spend too much time in the fed state, you remain sugar burning, which signals to your metabolism “keep storing fat.” When you spend too much time in the fasted state, your metabolism can see this as a threat to survival, so it slows metabolic rate and weakens your immune system.

The magic is in the adaptation. World-class personal trainers and fitness coaches understand how this works—they are constantly creating different workout routines for their clients because they know that if they keep the muscles adapting to changes, the body achieves better results. This same principle can be applied to your metabolism. When you master the art of switching back and forth between the fed and fasted state, this adaptation creates lasting results. This is how I have helped thousands of people break weight-loss resistance.

2. Preventing Cancer

Whether we “get cancer” is in part (but not always) a result of factors that are due to cellular changes that get “turned on” or “turned off” by behavior that is within our own control, namely: not smoking; eating a healthy, whole-foods diet; and practicing stress-coping mechanisms, including getting enough sleep. We used to think that cancer was the result of an unlucky genetic lottery, and that once you got it there was nothing you could do about it. But there is an interplay between the pro-cancer and anti-cancer events in the body.

The immune system orchestrates what happens when a cell dies and needs to be carted away or grows too rapidly and needs to be neutralized. Anything that strengthens our immune systems is an anti-cancer factor, since our immune system is our first line of defense against runaway cells. On the other hand, anything that inflames our bodies, hampers our immunity, and contributes to the overzealous growth of cells can contribute to the growth of cancer. This includes a diet high in processed carbohydrates and seed oils and simply too much food, in the form of eating larger portions and more food more frequently throughout the day.

Cancer grew in the United States by 84 percent from 1969 until 2014 and only took a minor dip in the intervening years due to smoking cessation trends.¹¹ Once lung cancer retreated, the statistics on cancer began to look better, but other than smoking, which accounts for 35 percent of attributable risk for cancer, the second largest risk factor is obesity. People who have type 2 diabetes and are overweight have an 18 percent higher risk of cancer than those without type 2 diabetes or obesity.¹² The connection is simple: insulin is a growth hormone. It’s one of several nutrient sensors that, when we eat, urge the cells to grow.

If you’re eating several snacks and meals throughout the day, then you’re constantly signaling the body to grow and grow and grow. When you eat macronutrients, especially carbs, that signals insulin. When you eat protein, that activates another nutrient sensor called mTOR, which is essential for protein synthesis. A third nutrient sense called AMPK responds to all three macronutrients—carbs, protein, and fat—and works long term. In each case, when you keep feeding your body 10 times a day, you’re telling the body to grow!

Researchers at the University of California, San Diego, reported that intermittent fasting reduced the risk of breast cancer in obese mice.¹³ They found that restricting eating to an eight-hour window, when activity was highest, decreased the risk of development, growth, and metastasis of breast cancer in mice. The findings, published in Nature Communications, demonstrated how time-restricted feeding, which is a form of IF, aligned with the circadian rhythms of the subjects and improved metabolic health and tumor circadian rhythms in mice with obesity-driven postmenopausal breast cancer.

“Previous research has shown that obesity increases the risk of a variety of cancers by negatively affecting how the body reacts to insulin levels and changing circadian rhythms,” said senior author Nicholas Webster, Ph.D., professor at UC San Diego School of Medicine. “We were able to increase insulin sensitivity, reduce hyperinsulinemia, restore circadian rhythms, and reduce tumor growth by simply modifying when and for how long mice had access to food.”

As we’ve seen before, elevated levels of insulin are damaging to the body. Research data indicated that elevated insulin levels in obese mice drove accelerated tumor growth. Artificially elevated insulin levels accelerated tumor growth, whereas reducing insulin levels could mimic the effect of the time-restricted feeding.¹⁴

Metabolic flexibility keeps insulin in check, slows cell growth, and helps prevent cancer.

3. Slowing the Aging Process

Although Father Time remains undefeated, the speed at which you age can be slowed down. The key to aging gracefully is to ensure that you remove what is interfering with your metabolism and give your cells all the necessary resources to function optimally. Supporting your cells, specifically your mitochondria, is the name of the game.

Your mitochondria love ketones. Ketones signal to your mitochondria to engage in mitochondrial biogenesis, the creation of new, healthy mitochondria. (I will teach you during the 30-Day Metabolic Freedom Reset which foods to eat to help your body produce ketones.)

Another way to improve mitochondrial function is to stress it (remember hormesis?). A short-term stress that allows your mitochondria to adapt helps them become stronger. This means your cells produce more energy and you burn more fat, produce less toxins, and age gracefully. Fasting is one of the best hormetic stressors for your mitochondria.

Your thoughts have a huge influence on your aging process as well. As you’ll learn later in the book, thoughts are frequencies that have the ability to penetrate your cell membranes and communicate with your DNA nucleus. If the thought is stressful or fearful, the signal sent is to produce inflammatory proteins. This shortens the telomeres around your DNA, which damages your DNA and ages you faster. If the thought is a positive and grateful thought, the signal sent to your DNA allows for anti-inflammatory proteins to be produced, lengthening your telomeres and protecting your DNA.^{15, 16} Think about that for a second!

4. Reversing Autoimmune Conditions

When you think of autoimmune conditions, imagine a three-legged stool. If any leg of this stool is weak, the stool will lose its function by collapsing. Each leg of the stool needs to be addressed. With autoimmune diseases, the three legs of the stool are the gut microbiome, stressors, and genetic predisposition. We are going to address all three legs in this book.

We already discussed how fasting can reset your gut microbiome by giving it a break to repair itself through the process of energy diversion. Studies suggest that ketone bodies can significantly influence gut microbiota, offering potential benefits for reducing inflammation and improving metabolic and neurological health.

Genetics play a role in autoimmune conditions, but not as much as you think. There’s growing research on the role of epigenetics, meaning “above the gene.” It’s true that you can’t change the genes you were born with; however, you have the power to turn them on or off. The cell membrane and the mitochondria are the key players in this process.

We can absolutely heal our mitochondria and bring in the healthy fats to support cell membrane fluidity. This enables our cells to detox more efficiently, allowing nutrients and hormones into the cell and releasing free radicals outside of the cell. This is how epigenetics works. Our lifestyle influences genes that get turned on, and it also influences genes that get turned off.

I personally have two autoimmune conditions: Reynaud’s syndrome and erythromelalgia. Raynaud’s syndrome is a problem that causes decreased blood flow to the fingers. In some cases, it also causes less blood flow to the ears, toes, nipples, knees, or nose. This happens because of blood vessel spasms in those areas. Erythromelalgia, also known as Mitchell’s disease, is a rare vascular disorder that causes pain, redness, and warmth in the extremities. The pain can be severe and burning, and the skin can become inflamed and hyperemic. Episodes can be constant or come and go, and they are often triggered by exercise or heat.

In 2018, I was visiting Seattle, Washington, with some friends, and we decided to take a day trip to a nearby alpine lake. We hiked for a couple of hours to get to one of the most beautiful scenes in nature I’d ever seen. The lake was fed directly by mountain snow, making the water extremely cold. I jumped in for a cold plunge for a couple of minutes. Upon exiting the water, I noticed my fingers were completely white. This was caused by the Raynaud’s. The whiteness of my fingers traveled to my wrists as my body was diverting all its blood flow away from my extremities. This was a scary feeling because I couldn’t even close my fist. I thought I was going to lose my fingers. I spent the next few minutes in a panic, looking for hikers who might be carrying a lighter. Thankfully, I found someone who gave me their lighter.

After 15 minutes of heating up my hands and fingers, the color returned to normal. This was an important lesson for me, as it showed me that I hadn’t gotten to the cause of my Reynaud’s syndrome yet. This is when I began to study the principle of hormesis. I was eating the right foods for my metabolism, but I hadn’t addressed my toxicity load up until this point. I implemented the metabolic strategies outlined in this book and built up my hormetic ceiling. I’m happy to share that I rarely get Reynaud’s symptoms these days. As a matter of fact, I own a cold plunge, and multiple times per week I find myself inside the plunge for three to four minutes at a time, without triggering any issues with my Reynaud’s syndrome.

My other autoimmune condition is erythromelalgia. It’s rare to have both Reynaud’s and erythromelalgia because they both seem to oppose each other. Erythromelalgia would be triggered for me after eating a meal, especially a meal high in carbohydrates. My fingers would immediately turn red, hot, swollen, and inflamed. It would be so bad that I’d have to seek something cold to hold in my hands to alleviate the pain.

I fixed my gut microbiome with the ancient healing strategies and toxicity-reducing methods in this book. I’m happy to report that my erythromelalgia symptoms rarely occur now. I share these stories with you because it proves that your body can heal itself. You have the ability to turn off bad genes and turn on good ones. You are in control.

5. Detoxifying Your Body

Burning stored body fat for energy can move toxins out of your cells for excretion. Your body has a highly sophisticated system in place for toxins. When toxins enter, a pathway called PPAR-y gets turned on to shuttle the toxins out of your bloodstream and into your fat cells. Many of these toxins are lipophilic (fat-loving), and your fat cells are the perfect home for them. By shuttling toxins into your fat cells, it allows your body to mitigate the damage because the solution to pollution is dilution. As you’ll learn later in this book, these toxins are called chemical obesogens because they increase fat cells, and your metabolism may recruit new fat cells to house these toxins. This process saves the body from harm in the short term while creating disease in the long term, unless it’s addressed properly.

When you follow the steps outlined in your 30-day Metabolic Freedom Reset, you’ll switch on fat burning, in which your metabolism burns stored energy (body fat) for fuel. When you practice intermittent fasting, it accelerates this process through autophagy, which is cellular cleanup. At this point all of your detox organs will move into action to ensure those toxins leave your system. Once you start using fat for energy, it mobilizes the toxins into your downstream detox pathways for removal. These detox pathways include your liver, kidneys, gut, gallbladder, and lymphatic system.

The more metabolic freedom you achieve, the more support these detox pathways will receive. Most people have closed detox pathways, which result in the following common symptoms:

• brain fog
• general and chronic fatigue
• constipation
• diarrhea
• skin abnormalities such as rashes
• feeling bloated after eating
• poor sleep

These symptoms are common, but they aren’t normal. I’ve seen people who have tried every detox in the world overcome these symptoms with the 30-Day Metabolic Freedom Reset. You just need to work on opening up those downstream detox pathways, so that your body will effortlessly work on removing them without you even noticing. (In Chapter 5, I will show you specific protocols that work best for opening up your detox pathways.)

♦ ♦

Your metabolism doesn’t have to slow down with age—it’s a myth that aging alone causes a metabolic decline. The truth is, metabolic efficiency hinges more on lifestyle choices than on the passage of time. Muscle loss, reduced activity, poor nutrition, and chronic stress are the real culprits behind a sluggish metabolism. By prioritizing the tips outlined inside this book, and supporting metabolic flexibility through smart dietary choices, you can maintain a metabolism at age 70 that functions as efficiently as it did in your teenage years. Aging is inevitable, but a slowing metabolism is not. It’s not just my opinion, recent scientific research challenges the common belief that metabolism inevitably slows with age. A comprehensive study published in Science analyzed data from over 6,600 individuals ranging from infancy to 95 years old. The findings revealed that, after accounting for body size and composition, total energy expenditure remains relatively stable from age 20 to 60—and even then, the changes are minimal after 60, with a gradual slowdown of approximately 0.7 percent per year.¹⁷ I believe that even this modest slowdown can be prevented with the strategies in this book.

Now that you have a strong foundational understanding of the science of how your metabolism works, I’m excited to show you how to take these concepts and sync them with your hormonal needs. The following chapters will identify the main causes of metabolic dysfunction as well as the best ways to remove this interference and restore your metabolism for good. In the next chapter we’ll examine the first cause: constant glucose and insulin spikes.