Valter Longo’s new book Fasting Cancer is a must-read. It's a powerful reminder that fasting can be a critical part of healing, but not always on its own. The #1 thing that stood out to me throughout this book was that the highest odds of survival come from combining fasting with standard medical care. 

Fasting + refeeding with whole plant foods can be a game changer. 

What struck me most were the charts showing how ineffective chemotherapy alone, or fasting alone, can be, compared to how incredibly powerful they are together. 

Here’s why: something called differential stress resistance (DSR). When we fast, our healthy cells protect themselves—forming a sort of shield, but cancer cells don’t. So when chemo or radiation is introduced, the healthy cells are protected, but cancer cells are exposed and targeted.

There’s even data showing that fasting + Vitamin C improves results 10x compared to Vitamin C alone (in colorectal cancer cases). 😮

Strength training also came up again and again—for every type of cancer he covered: breast, gynecological, prostate, colorectal, lung, blood, brain, skin, kidney. We must move our bodies.

Longo's message is clear: fasting - especially the 5 day fasting mimicking diet (which he states cancer clinics around the world are using over water-only fasting) - can make cancer treatments like chemo, radiation, or immunotherapy work better. It weakens the cancer cells (killing more of them) while helping healthy cells protect themselves. 

"...45 percent of the masses removed from patients who combined most chemo cycles with the fasting-mimicking diet were 90 to 100 percent cancer free, whereas only 20 percent of the masses removed from patients receiving chemotherapy while on a regular diet were 90 to 100 percent cancer free..."   (Fasting Cancer by Valter Longo, PhD; p. 73 from the study, "Fasting-Mimicking Diet as an Adjunct to Neoadjuvant Chemotherapy for Breast Cancer in the Multicentre Randomized Phase 2 DIRECT Trial," Nature Communications  11, no.1 (June 23, 2020): 3083.)

📘 Main Points: Fasting Cancer by Valter Longo

• Fasting—especially the 5-day fasting-mimicking diet (FMD)—can make standard cancer treatments more effective.

• Healthy cells enter a protective mode during fasting, while cancer cells remain exposed. This is called differential stress resistance. (DSR)

• Longo emphasizes: fasting is not a cure—it's best paired with medical treatment.

• For late-stage cancers, fasting may be more helpful alongside treatment, but again, only under medical supervision.

• Longo's long-term guidance: eat mostly plant-based or vegan, keep protein low and prioritize legumes (or fish twice a week), use time-restricted eating (12 hours every day), and repeat periodic FMDs (2-3 times a year for healthy individuals)
• Move your body. Start with walking. Aim for strength training 2x/week. 

Some of the online reviews for the book complain that it doesn't include any information on the FMD itself. If you're in that camp, grab your free DIY FMD guide 👉 our 5 day reset fasting guide.