Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar

by Jessie Inchauspé

Glucose is our body’s main source of energy. We get most of it from the food we eat, and it’s then carried in our bloodstream to our cells. Its concentration can fluctuate greatly throughout the day, and sharp increases in concentration—I call them glucose spikes—affect everything from our mood, our sleep, our weight, and our skin to the health of our immune system, our risk for heart disease, and our chance of conception.

Glucose isn’t everything. There are other factors that determine our health: sleep, stress, exercise, emotional connection, medical care, and more. Beyond glucose, we should pay attention to fat, to fructose, and to insulin, too.

My mother often sends me a photo of something she is debating buying at the supermarket. “Good or bad?” she texts. I always respond, “It depends—what would you eat instead?”

Van Helmont planted a 5-pound baby willow tree in a large pot filled with 200 pounds of soil. For the next five years, he watered it and watched it grow. Then, after those five years had passed and the tree had grown, he took the tree out of the pot and weighed it again: it stood at 169 pounds—164 pounds heavier than it had been at the beginning. But most important, the weight of the soil in the pot remained virtually unchanged. That meant that the 164 pounds of tree had to have come from somewhere else. So how do plants make their… plant stuff, if it isn’t from soil? Back to the tiny sprout that just saw the light of day on Earth. Let’s call him Jerry. Jerry was the first to put together a very elegant solution: the ability to transform not soil but air into matter. Jerry combined carbon dioxide (from the air) and water (from the soil, but not actually soil), using the energy of the sun, to make a never-before-seen substance that he uses to construct every part of himself. This substance is what we now call glucose. Without glucose, there would be no plants and no life.

photosynthesis: the process of turning carbon dioxide and water into glucose using the energy of the sun.

Plants assemble glucose into long chains called starch in order to store it.

Plants concentrate fructose into fruit—apples, cherries, kiwis, and more—that they dangle from their branches. The purpose of fructose is to make fruit taste irresistible to animals. Why do plants want their fruit to be irresistible? Because they hide their seeds in them. It’s key to propagation: plants hope that animals will eat their fruit and their seeds will go unnoticed until they come out their eater’s other end. That’s how seeds spread far and wide, thereby ensuring plants’ survival.

Your cells, like all animal and plant cells, need energy to stay alive—and glucose is their prioritized energy source. Each of our cells uses glucose for energy according to its specific function.

although glucose is needed to fuel your body’s systems, fructose isn’t. We eat a lot of unnecessary fructose in our diet nowadays, because we eat a lot more sucrose (which, as a reminder, is half glucose, half fructose).

Any part of a plant we eat turns back into glucose (and fructose) as we digest it, except for fiber, which passes right through us.

Why carbohydrates? Because it refers to things that were made by joining carbon (carbo) and water (hydrate), which is what happens during photosynthesis. You may have heard of this family under its popular nickname, carbs. Carbohydrates = Starch and Fiber and Sugars (glucose, fructose, sucrose)

scientists decided to make a subgroup for the smallest molecules: glucose, fructose, and sucrose. This subgroup is called sugars.

because glucose is so important to our cells, if we can’t find any to eat, our body can make it from within. That’s right, we don’t photosynthesize and make glucose out of air, water, and sunlight, but we can make glucose from the food we eat—from fat or protein. Our liver, through a process called gluconeogenesis, performs this process.

when glucose is limited, many cells in our body can, when needed, switch to using fat for fuel instead. This is called metabolic flexibility.

some diets such as Atkins and keto deliberately restrict the consumption of carbohydrates in order to keep a person’s glucose levels extremely low and thus push the body into burning fat for fuel. This is called n...

Today, however, the vast majority of supermarket shelves are packed with products that contain mostly starch and sugar. From white bread to ice cream, candy, fruit juices, and sweetened yogurts, fiber is nowhere to be seen. And this is on purpose: fiber is often removed in the creation of processed foods, because its presence is problematic if you’re trying to preserve things for a long time.

Fiber is often removed from processed foods so that they can be frozen, thawed, and last on shelves for years without losing their texture.

The basis of food processing is to first strip away the fiber, then concentrate the starch and sugars.

Why do we like sweetness so much? It’s because in Stone Age times the taste of sweetness signaled foods that were both safe (there are no foods that are both sweet and poisonous) and packed with energy. In a time when food wasn’t easy to find, it was an advantage to eat all the fruit before anyone else could, so we evolved to feel pleasure when we tasted something sweet.

by boiling sugarcane and crystallizing its juice, humans created table sugar—100 percent sucrose. This new product became very popular in the eighteenth century.

The starch and sugar turned into glucose after we swallowed them; they landed in our stomach, then entered our small intestine. There, the glucose disappeared through the lining of our gut and moved into our bloodstream. From our capillaries—tiny blood vessels—it moved to larger and larger vessels,

But what the ADA describes as “normal” may not actually be optimal. Early studies showed that the thriving range for fasting glucose may be between 72 and 85 mg/dL. That’s because there is more likelihood of developing health problems from 85 mg/dL and up.

The ADA states that our glucose levels shouldn’t increase above 140 mg/dL after eating. But again, that’s “normal,” not optimal. Studies in nondiabetics give more precise information: we should strive to avoid increasing our glucose levels by more than 30 mg/dL after eating. So in this book I will define a glucose spike as an increase in glucose in our body of more than 30 mg/dL after eating.

Another way to describe flattening your glucose curves is reducing glycemic variability. The smaller your glycemic variability, the better your health will be.

A glucose spike from a sweet food (cupcake) is worse for our health than a glucose spike from a starchy food (rice). The reason has nothing to do with the glucose measured, though; it has to do with a molecule that’s not visible.

A sweet food contains table sugar, or sucrose—that compound made up of glucose and fructose. A starchy food doesn’t. Whenever we see a glucose spike from a sweet food, there is a corresponding fructose spike that unfortunately we can’t see. Continuous glucose monitors can detect only glucose, not fructose, and continuous fructose monitors don’t exist yet.

Until they do, remember that if the food you ate was sweet and it created a glucose spike, it also created an invisible fructose spike, and that’s what makes a sweet spike more harmful than a starchy spike.

Each of us is made up of more than 30 trillion cells. When we spike, they all feel it. Glucose’s primary biological purpose once it enters a cell is to be turned into energy.

To understand how mitochondria respond to a glucose spike coming their way, imagine this: your grandfather, finally retiring after a long career, is able to fulfill his dream of working on a steam train. Everyone in the family thinks he’s crazy for doing it, but he doesn’t care. After some training, he enlists as a stoker in a train’s engine room: his job is to shovel coal onto the fire to generate the steam that pushes the pistons and makes the wheels of the train turn. He’s the mitochondria of the train, if you will. Periodically throughout the day, as the train speeds along the tracks, coal is delivered to your grandfather. He places it by the furnace and shovels it into the flames at a steady pace to fuel the process that moves the train. The raw material is converted to energy. And when the stock is used up, another batch is promptly supplied. Just like the train, our cells hum along smoothly when the amount of energy that is provided matches up with the amount of energy needed to function. Now it’s the second day of your grandfather’s new job. A few minutes after the first delivery of coal, he gets a surprising knock on the door. More coal. He thinks, Well, it’s a bit early, but that way I’ll have some extra. He sets it aside next to the furnace. A few minutes later, another knock. More coal. And another. The knocks keep coming, and the coal keeps being delivered. “I don’t need all of this!” he says. But he’s told that it’s his job to burn it, and he’s given no other...

According to the latest scientific theory, the Allostatic Load Model, when our mitochondria are drowning in unnecessary glucose, tiny molecules with large consequences are released: free radicals. (And some glucose is converted to fat; more on that shortly.) When free radicals appear because of a spike, they set off a dangerous chain reaction. Free radicals are a big deal because anything they touch, they damage. They randomly snap and modify our genetic code (our DNA), creating mutations that activate harmful genes and can lead to the development of cancer. They poke holes in the membranes of our cells, turning a normally functioning cell into a malfunctioning one. Under normal circumstances, we live with a moderate amount of free radicals, and we can handle them—but with repeated spikes, the quantity produced becomes unmanageable. When there are too many free radicals to be neutralized, our body is said to be in a state of oxidative stress.

Oxidative stress is a driver of heart disease, type 2 diabetes, cognitive decline, and general aging. And fructose increases oxidative stress even more than glucose alone. That’s one of the reasons that sweet foods (which contain fructose) are worse than starchy foods (which don’t). Too much fat can also increase oxidative stress.

In 1912, a French chemist by the name of Louis-Camille Maillard described and gave his name to this phenomenon, now known as the Maillard reaction. He discovered that browning happens when a glucose molecule bumps into another type of molecule. That causes a reaction. The second molecule is then said to be “glycated.” When a molecule is glycated, it’s damaged. This process is a normal and inevitable part of life, and it’s why we age, why our organs slowly deteriorate, and why we eventually die. We can’t stop this process, but we can slow it down or speed it up. When we toast bread, we make it brown. Our insides are browning just like this. The more glucose we deliver to our body, the more often glycation happens. Once a molecule is glycated, it’s damaged forever—which is why you can’t untoast a piece of toast. The long-term consequences of glycated molecules range from wrinkles and cataracts to heart disease and Alzheimer’s disease. Since browning is aging and aging is browning, slowing down the browning reaction in your body leads to a longer life. Fructose molecules glycate things 10 times as fast as glucose, generating that much more damage. Again, this is another reason why spikes from sugary foods such as cookies (which contain fructose) make us age faster than do spikes from starchy foods such as pasta (which doesn’t).

The combination of too many free radicals, oxidative stress, and glycation leads to a generalized state of inflammation in the body.

The World Health Organization calls inflammation-based diseases “the greatest threat to human health.” Worldwide, three out of five people will die of an inflammation-based disease. The good news is, a diet that reduces glucose spikes decreases inflammation and along with it your risk of contracting any of these inflammation-based diseases.

One of the pancreas’s main functions is to send a hormone called insulin into the body. Insulin’s sole purpose is to stash excess glucose in storage units throughout the body, to keep it out of circulation and protect us from damage. Without insulin, we would die; people without the ability to make it—who have type 1 diabetes—must inject insulin to make up for what the pancreas can’t produce.

Our liver turns glucose into a new form, called glycogen. It’s equivalent to how plants turn glucose into starch. Glycogen is actually the cousin of starch—it’s composed of many glucose molecules attached hand to hand. If excess glucose stayed in its original form, it would cause oxidative stress and glycation. Once transformed, it does no damage. The liver can hold about 100 grams of glucose in glycogen form (the amount of glucose in two large McDonald’s fries). That’s half of the 200 grams of glucose that our body needs for energy per day.

The liver and muscles are efficient, but we tend to eat much more glucose than we need, so those storage units get full rather quickly. Fairly soon, if we didn’t have another storage unit for extra glucose, our body would lose its game of Tetris. Which part of our body can we grow very easily, without much effort and just by sitting on our couch? Introducing our fat reserves. Once insulin has stored all the glucose it can in our liver and muscles, any glucose beyond that is turned into fat and stored in our fat reserves. And that’s one of the ways we put on weight. And then some. Because it’s not just glucose that our body has to deal with, it must also dispose of fructose. And unfortunately, fructose cannot be turned into glycogen and stored in the liver and the muscles. The only thing that fructose can be stored as is fat.

Humans store extra glucose as glycogen and fat. Extra fructose just turns into fat.

if two foods have the same amount of calories, I’d recommend that you skip the sweet food (which contains fructose) in favor of a savory food (which doesn’t). The absence of fructose means that fewer molecules end up as fat.

About 60 minutes after a meal, our glucose concentration reaches its maximum and then starts coming down as insulin arrives and ushers the glucose molecules away into our liver, muscles, and fat cells.

Second, constant hunger is a symptom of high insulin levels. When there is a lot of insulin in our body, built up over years of glucose spikes, our hormones get mixed up. Leptin, the hormone that tells us we are full and should stop eating, has its signal blocked, while ghrelin, the hormone that tells us we are hungry, takes over. Even though we have fat reserves, with lots of energy available, our body tells us we need more—so we eat. As we eat, we experience more glucose spikes, and insulin rushes in to store excess glucose as fat, which then increases the action of ghrelin. The more weight we put on, the hungrier we get. It’s an unfortunate, vicious, and unfair cycle. The answer is not to try to eat less; it is to decrease our insulin levels by flattening our glucose curves—and

A decrease in glucose levels—even a small decrease of 20 mg/dL, which is less than the 30 mg/dL dip that occurs after we spike—makes us crave high-calorie foods. The problem is, our glucose levels decrease all the time—specifically, they drop after every spike. And the higher the spike has been, the more intense the crash will be. That’s good, because it means insulin is doing its job, stashing excess glucose in various storage units. But it also means that we’re hit by a desire for a cookie or a burger—or both. Flattening our glucose curve leads to fewer cravings.

The same thing happens to our mitochondria: too much glucose makes them quit, energy production is compromised, and we are tired.

people born with mitochondrial defects can typically exercise only half as long as otherwise healthy people.

When we eat something that tastes sweet, we may think that we are helping our body get energized, but it’s just an impression caused by the dopamine rush in our brain that makes us feel high. With every spike, we are impairing the long-term ability of our mitochondria. Diets that cause glucose roller coasters lead to higher fatigue than those that flatten glucose curves.

starchy and sugary foods can set off a chain reaction that can show up as acne on your face and body and can even make your skin look visibly redder. This is because many skin conditions (including eczema and psoriasis) are driven by inflammation, which, as you learned, is a consequence of glucose spikes.

Children born today have a one in two chance of developing cancer in their lifetime. And poor diet, together with smoking, is the main driver in 50 percent of cancers.

Your brain doesn’t have sensory nerves, so when something is wrong, it can’t alert you with pain as other organs do. Instead, you feel mental disturbances—such as poor mood.

In a study performed at Duke University, women who went on a glucose level–flattening diet for six months cut their insulin levels by half

Glucose spikes, as I explained in the previous chapter, result in glycation—and glycation makes us age faster