One of the hardest moments in cancer is, surprisingly, the end of treatment. Everyone congratulates you. The doctors say you’re clear. And yet many people feel worse than ever: exhausted, anxious, and unsure how to rebuild their health.
So I spoke with nutritional therapist turned researcher Dawn Waldron who studies metabolic health after cancer. On her Substack, Fluxable, she explores how mitochondria, metabolism, and lifestyle shape long-term recovery. Dawn also writes from lived experience—she beat advanced triple negative breast cancer nearly 30 years ago.
In our conversation, we talked about why some doctors may only be “doing half the job” when it comes to cancer care, why she cautions against relying too heavily on supplements, and what it actually looks like to rebuild your body after treatment. We also discussed how the microbiome and mitochondria influence recovery, why chronic stress may play a role in cancer, and the things cancer survivors tend to over-focus on—and the ones they neglect.
You write a lot about metabolic health and “flux” after cancer. In plain language, what does that actually mean?
Flux is the electrical potential that moves along the membranes of mitochondria in all of our cells. It’s responsible for making energy—ATP—and ATP drives every reaction in the body. It drives gene expression, memory retrieval, breathing, movement, everything.
Researcher Martin Picard has said that the difference between a living person and a corpse is flux. Everything else is essentially the same. It’s only flux that changes.
Mitochondria are often described as the organelles that make energy, and that’s true, but they do much more than that. They regulate cell behavior. In fact, they may play a bigger role in cell behavior than DNA.
The key idea is that mitochondria are trying to keep this electrical current steady— not too much, not too little. A bit Goldilocks.
What fascinated me is that once you understand flux, many things we already know help in cancer suddenly make sense: exercise, sleep, antioxidants, melatonin, even the ketogenic diet. They all fit into the same framework.
When we say “metabolic,” what do we actually mean?
At the broadest level, metabolics refers to every chemical reaction in the body.
But quite often when nutritionists talk about metabolics, we mean the way we use fuel, this energy production process that takes place in the mitochondria. That’s the easiest way to think about it.
Many patients are told they’re in remission and then sent on their way. From a metabolic perspective, what’s missing from that moment?
That’s often one of the hardest moments for cancer patients.
When treatment finishes, people frequently feel depressed, exhausted, and a bit lost. And that isn’t just emotional. Metabolically, the body has taken a huge hit.
The microbiome is often at an all-time low. The gut wall may be damaged. There is usually significant inflammation in the body and even in the brain. And patients may have lost a lot of mitochondrial capacity along the way.
So yes, you may have no evidence of disease, which is wonderful, but your health still needs rebuilding.
Your tumor burden may have been massively reduced. But in the process you’ve been subjected to some of the most toxic medicines on the planet.
What’s missing is the next step: rebuilding resilience. Rebuilding mitochondrial health. Supporting the microbiome. Increasing exercise capacity again. Reducing inflammation.
At the moment we’re only doing half the job. We’re getting rid of the tumor cells, but we’re not rebuilding a healthy microenvironment that makes it less likely for new tumor cells to form.
You’ve said we should be tracking more things when patients are first diagnosed. What kinds of markers do you think matter?
We should simply be asking more curious questions.
Does this person exercise? Do they spend time outdoors in the sunshine? Are they drinking more than recommended alcohol levels? What are their vitamin D levels? What are their inflammatory markers like C-reactive protein? What are their blood sugar markers such as HbA1c?
I remember when I was diagnosed they were interested in some of my inflammatory markers after treatment, when I was clear. And I remember thinking: why weren’t you tracking that from the beginning?
We should be taking a much fuller statistical picture of patients and tracking it over time. We now have the computational power to do this easily. It would help us to find new avenues to explore. I can’t understand the lack of curiosity about this.
If cancer involves a metabolic shift, is recovery about reversing that shift?
In simple terms, yes.
If someone has no evidence of disease, recovery is largely about supporting the body so it can produce ATP smoothly and consistently again.
That means not constantly overloading the system with calories or carbohydrates, keeping insulin under control, matching food intake with physical activity, supporting antioxidant status, and rebuilding a healthy microbiome.
Circadian rhythm also plays an important role. Having long overnight periods without food, getting daylight during the day, and darkness at night all support mitochondrial function.
You can never say with certainty that cancer will never return, but supporting healthy metabolic function dramatically reduces risk.
