How Cancer Uses Fuel and Why That Matters

Once we start talking about sugar and blood sugar, a question often comes up:

“So… what does cancer actually use for fuel?”

Let’s take a breath.

This isn’t about fear.
And it isn’t about starving your body.

It’s about understanding how cancer cells behave differently than healthy cells and why that difference matters when we’re thinking about supportive healing.

When we understand the biology, we move from confusion to clarity. And clarity feels empowering.

Healthy Cells Are Flexible

Healthy cells are remarkably adaptable.

They can use:

• Glucose (from carbohydrates)

• Fatty acids

• Ketones (produced when fat is broken down in the body)

This flexibility is called metabolic flexibility. It allows healthy cells to continue functioning even when fuel sources shift.

Think of healthy cells like hybrid cars.  They can switch fuel sources depending on what’s available.

It’s one of the body’s many built-in survival mechanisms.

Cancer Cells Are Far Less Flexible

Cancer cells, however, tend to rely very heavily on glucose for energy. Harvard Medical School reported that up to 80% of all human cancers are driven by glucose pathways in the body.

This phenomenon is referred to as the Warburg effect where cancer cells use glucose in a less efficient, fermentation-like process even when oxygen is present.

In many cases, cancer cells use glucose up to 50 times faster than healthy cells.  And compared to healthy cells, they are much less efficient at using fat and ketones for fuel.

This difference is important, not because it means we can “starve” cancer, but because it helps explain why metabolic signals matter.

When glucose and insulin are frequently elevated:

• Growth signals increase

• Inflammatory signaling rises

• The internal terrain becomes more supportive and conducive for cancer cells to flourish

This is not about blame.

It’s about biology.

The Mighty Mitochondria

Mitochondria are often called the “power plants”.  They produce the energy our body needs inside our cells.

In healthy cells, mitochondria efficiently produce energy through oxidative metabolism.

In cancer cells, mitochondrial function is impaired or altered. Because of this dysfunction, cancer cells rely very heavily on glucose-dependent pathways and the Warburg effect that are less efficient but allow for rapid growth.

Cancer cells struggle with fuel shifts and are much less flexible. This helps explain why cancer cells struggle when fuel availability changes while healthy cells adapt more easily.

What This Means for You

Supporting mitochondrial health and metabolic flexibility isn’t about controlling cancer.

It’s about strengthening resilience and creating an internal terrain where healthy cells flourish and cancer cells do not. 

We support our body's resilience when we:

• Stabilize blood sugar

• Reduce frequent insulin spikes

• Improve metabolic flexibility

• Support mitochondrial health

We help create a terrain that favors healthy cell function and inhibits cancer cells. 

This approach works alongside medical treatment, not instead of it.

It is supportive.
It is complementary.
It is empowering.

A Reassuring Reminder

Nothing here suggests that:

• You caused your cancer

• You can “fix” this with food alone

• You need to be perfect

This is about giving your body better signals and creating an optimal terrain, not adding pressure or fear.

Small, consistent shifts often matter more than extreme changes.

A Gentle Reflection

As you consider this information, you might ask yourself:

Where in my life do I feel I am supporting myself metabolically and where might I need more stability?

Awareness is the first step toward empowerment.

Next week, we’ll talk about a topic that often brings confusion and strong opinions:

The ketogenic diet: what it actually does, what it doesn’t do, and how to think about it in a cancer-supportive context without rigidity or fear.