Cancer cells do use glucose — but so do normal cells
Many cancer cells rely heavily on glucose for energy through a process called the Warburg effect.
They consume glucose at high rates even when oxygen is available.
However, glucose is also essential for:
Brain cells
Red blood cells
Immune cells
Muscles during activity
Healing and recovery
The body tightly regulates blood glucose.
Even if someone eats almost no carbohydrates, the liver can make glucose from:
Protein (amino acids)
Glycerol from fat
Other metabolic pathways
So a low-carb diet does not mean cancer cells receive zero glucose.
2. Why don’t doctors prescribe a ketogenic diet for everyone with cancer?
A ketogenic diet (very low carbohydrate, high fat) is being researched, but it is not proven to replace standard cancer treatments.
Possible problems during cancer treatment:
Weight loss and muscle loss can worsen outcomes, especially in advanced cancers.
Chemotherapy and radiation require the body to have enough energy and protein to repair tissues.
Some patients develop cachexia (cancer-related muscle wasting), where maintaining weight is a major goal.
For many cancer patients, the priority is:
✅ maintain strength
✅ preserve muscle
✅ tolerate treatment
✅ recover after surgery/chemotherapy
3. Could diet influence cancer risk or outcomes?
Yes, nutrition matters — but in a different way.
Evidence supports:
Maintaining a healthy body weight
Eating plenty of vegetables, fruits, legumes, and whole grains
Getting adequate protein
Limiting processed meats
Limiting excessive alcohol
Regular physical activity
These can reduce cancer risk and improve general health.
But there is currently no strong evidence that eliminating carbohydrates can cure cancer.
4. Are there situations where a ketogenic diet is studied?
Yes. Researchers are studying ketogenic diets in some cancers because lowering insulin and glucose availability may affect certain tumor pathways.
Early research has explored this in cancers such as:
Brain tumors (including glioblastoma)
Some breast cancers
Some metabolic-sensitive tumors
But results are mixed, and it remains an adjunct research approach, not a replacement for chemotherapy, immunotherapy, surgery, radiation, or targeted treatments.
5. Why did the doctors in the story advise against extreme dieting?
Because a newly diagnosed cancer patient often needs more nutritional support, not restriction.
For example:
A patient undergoing chemotherapy may need extra protein to maintain muscle.
A surgical patient needs calories for wound healing.
A person losing weight unintentionally may have a worse prognosis.
A balanced diet designed around the person's cancer type, treatment, symptoms, and nutritional status is usually recommended.
Cancer cells do use glucose, but “starving cancer by removing sugar” is not realistic because the body will still make glucose and cancer cells can adapt.
The strongest evidence still supports medical cancer treatments plus good nutrition to keep the body strong enough to fight and recover.
For someone with cancer, a good question for the oncology team is not “How do I remove all sugar?” but rather:
“What eating pattern will help me maintain muscle, energy, and tolerate my treatment best?”
