For over three decades, Dr. Thomas N. Seyfried has dedicated his life to one of biology’s biggest questions. He studies cancer not just as a genetic disease of “bad luck,” but as a metabolic one.
His research doesn’t just ask why cancer starts; it deeply explores how cancer cells feed, grow, and survive.
What’s the key takeaway from his 30+ years of work? The idea that we have more control than we think. Dr. Seyfried’s research suggests that many cancers can be managed, slowed, or prevented by fundamentally changing how our bodies are fueled.
If cancer cells are hungry, what are we feeding them?
This is a different way of thinking, and it’s empowering. It shifts the focus from just genetics to our daily metabolic health. Here are six key tips inspired by Dr. Seyfried’s metabolic approach to reducing cancer risk.
Important Medical Disclaimer: The information here is for educational purposes and is based on Dr. Seyfried’s research. It is not medical advice. Always consult your doctor or a qualified healthcare professional before making any significant changes to your diet, fasting schedule, or health regimen, especially if you have an existing medical condition.
1. Understand What Cancer Cells Eat
This is the central idea of the metabolic theory. Dr. Seyfried’s research shows that most cancer cells are metabolically inflexible. Unlike healthy cells, which can burn glucose (sugar) or ketones (fats) for energy, most cancer cells are desperately dependent on one main fuel source: glucose.
They also rely heavily on a second fuel, an amino acid called glutamine.
Healthy cells are metabolically flexible. Cancer cells are not. This “metabolic handicap” is their greatest weakness—and our greatest strength. The rest of these tips are about exploiting that weakness.
2. “Starve” Them with Therapeutic Fasting
If cancer cells love sugar, what happens when you take the sugar away?
Dr. Seyfried is a strong proponent of periodic, water-only therapeutic fasting (under medical supervision, of course). When you fast, your body’s glucose levels plummet. To survive, your healthy cells switch to a different power source: they start burning fat and producing ketones.
Your brain, heart, and muscles love ketones. But, as Dr. Seyfried argues, most cancer cells can’t use them for fuel. Fasting essentially pulls the rug out from under them, depriving them of their favorite food while nourishing your healthy cells.
3. Switch Your Fuel Source with Keto
You can’t fast forever. The long-term strategy for maintaining this low-glucose state is a well-formulated ketogenic diet.
This isn’t just about eating bacon and cheese. A therapeutic ketogenic diet is a high-fat, adequate-protein, and very-low-carbohydrate plan. The goal is the same as fasting: to shift your body from being a “sugar-burner” to a “fat-burner.”
By running on ketones, you create a metabolic environment where your healthy cells thrive, but cancer cells struggle to find the glucose they crave.
4. Manage Your Stress (It’s a Metabolic Problem)
This isn’t just fluffy, feel-good advice. Stress has a direct, measurable, metabolic effect.
When you’re chronically stressed, your body releases hormones like cortisol. What does cortisol do? It dumps glucose into your bloodstream to prepare you for a “fight or flight” response.
If you’re stressed all the time, your blood sugar is high all the time. You are, in effect, providing a constant, delicious buffet for any rogue cells that might be growing. Managing stress through meditation, sleep, or walking is a powerful metabolic tool.
5. Move Your Body, But Don’t “Over-Pulse”
Exercise is fantastic. It builds muscle, which helps stabilize your blood sugar. But Dr. Seyfried’s “press-pulse” theory offers a small warning.
He describes “press” strategies (like the keto diet) that apply constant, gentle pressure on cancer. He also describes “pulse” strategies (like fasting or specific therapies) that deliver a short, powerful hit.
Chronic, high-intensity, exhaustive exercise can be a “pulse” that actually increases inflammation and stress hormones (like cortisol). The key is moderate, consistent movement—like walking, swimming, or yoga—that supports your metabolic health without creating systemic stress.
6. Avoid Known Carcinogens (The Obvious One)
This is the common-sense tip that ties everything together. Dr. Seyfried’s theory begins with damage to the mitochondria (the tiny “power plants” in our cells). Once damaged, a cell reverts to the primitive, inefficient “fermentation” (glucose-burning) survival mode—what we call cancer.
What damages mitochondria? Toxins.
Things like smoking, excessive alcohol, and high exposure to industrial chemicals and processed food additives all put massive stress on your mitochondria. Reducing your exposure to these toxins is the first step in protecting your metabolic machinery.
Ultimately, Dr. Seyfried’s work offers a message of hope. By viewing cancer through a metabolic lens, we are no longer just victims of our genes. We are active participants in our health, capable of changing the very “soil” in which these cells either thrive or wither.
