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Home » No.1 Fasting Expert: Surprising Link Between Fasting & Cancer – DOAC Podcast (Transcript) 

No.1 Fasting Expert: Surprising Link Between Fasting & Cancer – DOAC Podcast (Transcript) 

Read the full transcript of fasting expert Dr Alan Goldhamer’s interview on The Diary Of A CEO with Steven Bartlett episode titled “Surprising Link Between Fasting & Cancer! It Resets Your Gut Microbiome”, September 1, 2025.

Who is Dr. Alan Goldhamer?

STEVEN BARTLETT: Dr. Alan Goldhamer. My first question is, who are you and what have you spent the last four decades of your life doing and why?

DR ALAN GOLDHAMER: I’ve spent my entire life really focused on one topic, and that’s this idea that health results from healthful living. I got interested really young. I was in elementary school, and I had decided that I wanted to pursue this as a career.

When I finished training in the United States, I had an opportunity to go to Australia. And I studied with a guy named Alec Burton, who was the world’s leading expert in the use of medically supervised water only fasting. And I saw things there that weren’t supposed to be happening. People were getting better.

I saw people with chronic diseases like high blood pressure resolving their hypertension, getting off the medications. And so we began to carefully evaluate patients with hypertension. In this study, 174 consecutive patients with high blood pressure and 174 people normalized their blood pressure without the need for medication.

After we published that paper, we went on and we’ve published a couple dozen papers now on the use of diet and fasting in the literature. And we’ve written a book, it’s called “Can Fasting Save Your Life?” Which summarizes our work and other people’s work on this use of fasting to help the body do what it really does best and which is heal itself if you get out of the way.

What Type of Fasting Does Dr. Goldhamer Practice?

STEVEN BARTLETT: So fasting, the word has become incredibly popular, but there’s a variety of different types of fasting. So what is the type of fasting that you spend most of your time doing working on administering to patients?

DR ALAN GOLDHAMER: Right. Well, fasting is the complete abstinence of all substances in an environment of complete rest.

STEVEN BARTLETT: So what does that mean?

DR ALAN GOLDHAMER: That means that you’re actually resting while you’re fasting in order to get therapeutic fasting to be most effective. And the reason is if you’re very active when you’re fasting, your body has to produce more glucose in order to carry on the extra muscular and brain activity.

And the only way that it does that after glycogen reserves are depleted is through a process called gluconeogenesis, where the body breaks down lean tissue. So when you’re fasting, if your goal is to maximize fat loss and minimize lean tissue loss, it’s important that resting be a part of the protocol.

It’s true if people are more active when they’re fasting, they’ll lose more weight, but that extra weight won’t be fat, it’ll be lean tissue.

The Physiological Process of Fasting

STEVEN BARTLETT: So what happens to the body when someone fasts? And can you give me like an hour by hour or a play by play in terms of what actually is the sort of physiological sequence of events that are beneficial for one’s health?

DR ALAN GOLDHAMER: So it’s a really interesting, fairly well studied and complex physiological adaptation that human beings make to fasting. Normally, your brain burns glucose, which is…

STEVEN BARTLETT: What I get if I have a piece of bread or a bar of chocolate.

DR ALAN GOLDHAMER: Or if you break down protein, which can also break down into glucose, which is what happens after 24 hours of fasting. You’ve depleted your glycogen storage sugar stores in your muscles. And so then the body, in order to get the glucose it needs, has to either convert to burning fat or break down muscle in order to form glucose.

What the human being does is it converts its main burner of glucose, which is the brain, from burning sugar to burning fat. Now, if it didn’t do that, you could fast about a week, you’d enter starvation, deplete your protein stores and you’d starve to death.

Because you can convert your brain to burning fat instead of sugar, a 70 kilogram male can fast about 70 days. Now, that doesn’t mean they should fast 70 days, but they could fast up to 70 days because your main burner of glucose, your brain will convert to burning a completely different fuel, which is fat.

STEVEN BARTLETT: So let me see if I’ve got this correct. So if I’m on a typical American diet, I’m going to be eating lots of things and my body’s going to be breaking that down into this fuel source called glucose. If I stop eating the glucose, my body has this sort of evolutionary switch where it’s going to start burning my fat and turning that into this thing called ketones, which my brain can run on as well.

DR ALAN GOLDHAMER: That’s correct. And you have about 24 hours of glycogen stores or sugar stores in your muscles, in your liver. So when you stop eating for the first 24 hours, you’re still able to produce glucose from your glycogen stores.

But once you’ve depleted your glycogen source, now you’re stuck. You either burn fat or you break down lean tissue. Now, because the human brain is so ridiculously large, I mean, it’s two and a half times a chimp’s, it’s a huge glucose burning machine.

You had to have a way of being able to use some kind of other fuel for that brain. Otherwise, the first time spring comes late, all the human beings would have died. And so this biological adaptation was clearly important for our survival in large part because we have disproportionately large brains that burn ridiculous amounts of glucose.

Is This Evolutionary Mechanism Actually Healthy?

STEVEN BARTLETT: Just because the body does it as a survival mechanism doesn’t posit that it’s necessarily healthy, though, right?

DR ALAN GOLDHAMER: Absolutely. And what we’ve done though, is we’ve taken this biological adaptation, which by definition would be something the body’s capable of doing safely and efficiently and utilizing it in a very unusual situation.