Glucose, Fat, and the Hormone That Regulates Them
How Your Body Turns Food into Fuel—And Why That Matters
Your body is remarkably adaptable. Every time you eat, it gets to work converting that food into energy. It decides what to use now, what to store for later, and how to keep things running smoothly. At the center of this process are three key elements: the body’s two main fuel sources—glucose and fat—and the hormone that helps your body use them: insulin.
Understanding how they work together can help explain why your energy rises and falls, why some foods affect you more than others—and why small changes in how you eat, move, and sleep can make a real difference.
The Fuel Shift
After a meal, your blood sugar rises—especially if you’ve eaten carbohydrates. In response, your pancreas releases insulin. This hormone acts like a key, unlocking cells so they can absorb glucose from your blood and either burn it for energy or store it for later.
Your body stores extra glucose in two main ways: first as glycogen in your liver and muscles, and then—once those stores are full—as fat, initially in subcutaneous tissue (which means under the skin). When that storage space becomes limited, excess fat may be stored viscerally, especially around the organs in the abdomen—a shift that’s linked to increased insulin resistance, inflammation, and a higher risk of metabolic disease—a group of conditions like high blood pressure, high blood sugar, unhealthy cholesterol levels, and excess belly fat that raise your risk for heart disease and diabetes.
Insulin does more than just move sugar. It also signals your body to pause fat burning. When insulin is high, your body relies more on glucose for fuel. When insulin drops—such as between meals or overnight—your body can switch to burning stored fat instead.
That ability to move smoothly between fuel sources is known as metabolic flexibility. It’s a sign of a healthy, efficient metabolism.
When the System Slows Down
Problems arise when the system becomes less responsive—when your cells stop listening to insulin’s signals. This is called insulin resistance, and it can lead to a host of metabolic challenges.
When cells resist insulin, your body compensates by producing more of it. Over time, insulin levels stay elevated, even between meals. That makes it harder to access stored fat, disrupts energy balance, and can drive weight gain, especially around the waist. Eventually, blood sugar rises too—and that’s when many people are first diagnosed with prediabetes or type 2 diabetes.
But long before that diagnosis, the body has been giving clues: fatigue, cravings, stubborn weight, or labs that are “normal” but not optimal.
Fat as Fuel
Fat often gets a bad reputation, but it’s actually one of your body’s most efficient energy sources. When insulin levels are low, your body taps into stored fat and breaks it down into free fatty acids. These fatty acids are transported to the mitochondria—the energy centers in your cells—where they’re processed through a pathway called beta-oxidation to produce long-lasting energy.
When metabolic flexibility is strong, your body shifts smoothly between burning sugar and fat, depending on your activity, stress, and the time since your last meal. When flexibility is lost, you get stuck in sugar-burning mode—leaving fat stores unused and energy levels inconsistent.
At Ikigai Health Institute, we look for these early shifts in metabolic function using tools like continuous glucose monitoring (CGM), DEXA scans to assess fat and muscle composition, VO2 Max/physiology testing, and advanced lab work to help you better understand how your body handles fuel.
Small Shifts, Meaningful Results
You don’t need extreme diets or complicated rules to improve your metabolic health. In fact, some of the most powerful strategies are simple:
Build meals around protein, fiber, and healthy fats
Go for a short walk after eating
Avoid constant grazing—let your body rest between meals
Strength train a few times per week
Prioritize 7–9 hours of sleep
Find ways to manage daily stress
These habits help regulate blood sugar, lower insulin levels, and encourage your body to use both glucose and fat effectively.
Your Metabolism Is Adaptable
Glucose and fat metabolism aren’t fixed—they respond to how you live. At Ikigai, we focus on understanding your unique physiology so we can guide you toward the habits and strategies that support energy, longevity, and strength.
This isn’t about chasing perfection. It’s about building a foundation you can trust—so your body has what it needs to move, think, and feel its best for years to come.
This is our Ikigai mission
