


Fasting — A Powerful Metabolic Intervention That Can Dramatically Boost Your Health

Story at-a-glance -

  • At 62, and having a diagnosis of atrial fibrillation, George Newman is an inspiring example of how simple lifestyle strategies can turn your health around. He’s keeping his AFib under control with a combination of keto adaptation, fasting and magnesium supplementation
  • Endurance exercise raises your risk for AFib by putting undue stress on your heart. Magnesium deficiency and electromagnetic field exposure also raise your risk
  • Incidentally, EMF toxicity is mitigated through your voltage-gated calcium channels. Since magnesium is a natural calcium channel blocker, it helps block the adverse effects of EMF
  • Water fasting provides many benefits, from saving money and having greater mental clarity to radically improving your body's ability to digest damaged cells (autophagy) and increasing healing stem cells
  • By fasting five days out of every 14, Newman goes far beyond what most will attempt, and his lab work shows it does not impair health — it improves it. After 13 cycles of five-day fasts every two weeks, he has not lost any muscle mass, and his bone density is that of someone half his age

By Dr. Mercola

I hope you all are recovering well from a well-deserved holiday weekend in the U.S.  I am beyond excited to introduce you to a remarkable individual who inspired me to implement what I believe is the most powerful metabolic health intervention you can undergo. Although it is the cure for over 80 percent of the population that has insulin resistance it is also helpful for all of us.  So much so that I have committed to monthly five-day fasts and as you read this I am in the third day of a five day fast.

In this interview, George Newman, whom I met while lecturing at a low-carb conference in San Diego this past summer, discusses many important details of: multiple day water fasts. Newman has no formal health training. He's an engineer, but he really knows his stuff and talking to him inspired me to re-evaluate my stance on extended water fasting, which I didn’t think was necessary in the absence of obesity, diabetes or some other specific health challenge such as cancer.

“I've had a long and interesting health journey,” Newman says. “Thirteen years ago, I ended up with atrial fibrillation (AFib). In my case, it was brought on by excessive or chronic fitness … At that point I was participating in high altitude long distance races. I was doing fairly intense training.

For example, the Pikes Peak Ascent race, which would start out at 6,300 feet and go to 14,100 feet over 13 miles. It was after a training run that I got my first AFib episode … I had a parasympathetic response, a vagal trigger to AFib, which means that my system … got very slow for a couple of days and that slowness [became] a trigger for my AFib.

The short story of that is I managed, after a two-and-a-half-month episode, to create a regimen for myself that includes a lot of high-dose magnesium, which has kept me relatively in rhythm for most of that time. I did detrain. I don't do chronic long distance endurance exercise anymore. I am still fit (with rock climbing, alpine skiing, HIIT and bodyweight exercise) but I've taken that out of my routine.”

Addressing AFib

As a result of this incident, and refusing to accept the conventional medical wisdom that advocates taking medication or undergoing cardiac ablation surgery, he began researching how to optimize his health. AFib is a condition where there’s increased or aberrant electrical activity in the atrium, the smaller chamber of the heart.

Essentially, the chamber contracts erratically and isn't able to sync with the ventricles in a proper 1-to-1 ratio. AFib is a fairly common problem among endurance athletes. While there’s a genetic component, endurance exercise raises your risk by putting undue stress on your heart. Your heart is actually designed to work very hard in short spurts, not continuously for long periods of time. That said, extreme athletes are still a relatively small subset of people who get AFib. Most are older and have other comorbidities.


Magnesium Is Extremely Important for Optimal Heart Health

As mentioned, magnesium is a supplement Newman now takes daily, and in very high amounts. At one point he was taking up to 5.5 grams of elemental magnesium a day. These days, he’s typically taking 1.5 grams daily, which is still a far cry from the recommended dietary allowance of 400 mg per day. It’s rather difficult to overdose on magnesium, though, as it has a laxative effect. If you take more than your body needs, it’ll just come out the other end.

The fact he was able to tolerate over 5 grams a day without getting diarrhea also suggests he was sorely depleted. It’s worth noting that intense exercise does deplete magnesium, so if you exercise a lot, you need more magnesium than you would if you were inactive.

“The total body store of magnesium is about 30 grams, including the bones and everything,” he says. “Why I wasn't hanging on [to the magnesium] I've never quite figured out. Whatever it is, I have done [high-dose intervals] several times. When I first figured out my routine of high magnesium and detraining, I had a period of two years without an AFib event and I thought, ‘Oh, I've had reverse remodeling, I'm cured and I don't need these supplements.’

So, I quit taking them. Within 24, 48 hours, I was in AFib. I'm like, ‘OK, I don't need to repeat that,’ and so I haven't intentionally [stopped taking magnesium] since. I don't want to give people the impression that this is an easy thing to do. It worked for me and it's probably worth trying, but it is fairly rare that you can do this.”

While Newman’s AFib remission strategy of magnesium and detraining works very well, it is not 100 percent perfect. In addition to magnesium, Newman does use a prescribed medication, flecainide, on-demand to convert himself into normal rhythm when the magnesium strategy fails.

In the last 4.5 years, he’s gone into AFib four times for a total of about five hours out of rhythm. For those with compromised kidney function, electrolyte supplementation may need to be avoided altogether. In those with normal kidney function, excess electrolytes will be excreted.

Electromagnetic Field Exposure Can Trigger AFib

On a side note, aside from chronic overexercise and magnesium deficiency, exposure to electromagnetic fields (EMF) can also increase your risk of AFib. This effect has been well-documented, and includes not only cellphones and Wi-Fi but also the electric wiring in your walls.

Ideally, you need to sleep in an EMF-free environment, especially if you have AFib. The simplest way to do that is to shut down the electricity to your bedroom, assuming your bedroom isn't surrounded by other rooms adjacent to it, in which case you would need to actually measure the electric fields.

Interestingly, one potential reason why Newman does not appear to be affected by EMF may well have to do with his magnesium loading. We know from Dr. Martin Pall’s work that EMF toxicity is mitigated through your voltage-gated calcium channels. Since magnesium is a natural calcium channel blocker, it helps block the adverse effects of EMF.

Still, the fact that you don’t notice a sensitivity to EMF does not mean it’s not causing some kind of damage. Research has shown damage occurs whether the person is sensitive enough to feel it or not.

You May Need More Magnesium Than You Think

In George’s case, it appears his AFib was triggered by low magnesium caused by endurance exercise, which subsequently upset his potassium-to-magnesium balance. By taking supplemental magnesium, his potassium level also balanced out. To determine your magnesium level you could do an erythrocyte red blood cell (RBC) magnesium test.

“Dr. Caroline Dean does a lot of work with magnesium. Looking at the RBC magnesium levels, she suggests, at the high end of normal, 6 to 6.5 mg/dL as a good range. The first time I ever tested, before I had backed off [magnesium] a little bit was 7.8, and a more recent test was around 7.5 mg/dL.”

I too took this test recently for the first time. At the time, I was taking over 1 gram of magnesium per day. Surprisingly, my RBC magnesium was only 3.5, which is below average. It didn't make any sense and, like Newman, I’m presently at a loss as to why my level would be so low when I’m taking such a high dosage.

“I know that there are people in my AFib world and there are some people that are very sensitive to magnesium levels. One of my friends was taking intermuscular magnesium and also doing IV magnesium for quite a while to keep his levels up. I know there are people that do this,” Newman says.

“Herbert Mansmann, a large man [and] Type 2 diabetic, spent the latter part of his life as a retired pathologist studying magnesium. There are papers written by him and at one point he took 20 grams a day for a year. He was able to actually mitigate the diabetic neuropathy symptoms in his legs by doing that. It was his work that [made me] realize I'm probably not going to have a problem overdosing on [magnesium].”

The Benefits of Magnesium Bicarbonate

In the early ‘90s, Australian ranchers observed that sheep drinking from a particular spring had better health outcomes. When they tested the water, they found it was relatively high in magnesium bicarbonate. Following in the footsteps of some of George’s AFib acquaintances, I started making a magnesium water drink. By adding milk of magnesia to chilled carbonated water, you create magnesium bicarbonate.1

I used a SodaStream to create the carbonated water rather than buying bottled soda water, and bought additive-free magnesium hydroxide, commonly known as milk of magnesia. Most of the magnesium hydroxide sold contains additives. You can also use magnesium acetate. The reason you have to do this exotic preparation is because magnesium bicarbonate is not available in powder or pill form. It must be created through this chemical reaction.

Now, it does not taste very good, and after discussing the matter with Tyler LeBaron, a chemist with the Molecular Hydrogen Foundation, I learned there’s really nothing special about magnesium bicarbonate per se. As long as you're getting the ionic magnesium and the carbonate, you're going to get the benefits.

So, I now take potassium bicarbonate on a nightly basis instead. This provides the beneficial carbonate ions, and provides a little alkalization as well. I’m going to experiment with the potassium bicarbonate in combination with high-dose magnesium while monitoring my magnesium level monthly to see if I can improve my level this way.

“Another way you can get it is [by using] magnesium acetate. You can do that, again, with milk of magnesia, and I use organic apple cider vinegar in a ratio of 2-to-7 (two parts milk of magnesia to seven parts vinegar). That creates magnesium acetate, which from what I understand converts to magnesium bicarbonate in the body. That's a quick reaction. The magnesium bicarbonate reaction with carbonated water does take a while,” Newman says.

“There's lots of different types of magnesium and people talk about what's best. For my primary purpose, which is the AFib, in my case any magnesium works. I can take magnesium oxide, I can take citrate, bicentate, you name it, it doesn't matter. I just need to take it, take it regularly and take it in sufficient quantities.”

Fasting — A Powerful Metabolic Therapy

Newman has really enlightened and motivated me by example about the profound benefits of water fasting, even when you do not have a weight or insulin problem. With a fasting insulin level of less than 2, I really did not think fasting would benefit me. Newman, however, inspired me to revisit this topic, and thanks to our discussions, I now fast for four or five days at a stretch. My first fast was a four-day fast, and I now do a monthly five-day fast.

I actually look forward to it now. There's no pain. You can get more done — the mental clarity is just profound, not to mention it makes life easier and less expensive since you don’t have to buy, prepare, eat or clean up food for a few days. What I'm most excited about is the fact that it radically improves your body's ability to digest damaged cells, a process we called autophagy. It also increases stem cells. Newman explains:

“When you look at Valter Longo's work … their aha moment was when cancer model rodents, mice, were fasted before chemo, during chemo, after chemo and then refed until they came back to their before-fast weight … Chemo will normally knock your white blood cell count way down, but after six or seven cycles [of fasting and refeeding], they noticed that these mice had the white blood cell count of young mice and not cancer model mice with a lot of chemo.

That was intriguing to me. A question I have is, how long must the fast be to really get this [effect]? Because they figured out that the stem cells in these mice were creating new white blood cells … I listened to an interview that Rhonda Patrick had with Guido Kroemer.

He's a colleague of Valter Longo's … He mentioned that a mouse, when you fast it for a day, loses 10 percent of its body weight … My point is that if I fast for five days, it’s nowhere comparable to fasting a mouse for two days. So, a question I have is how long do you really need to fast to bring that [stem cell effect] out, and I don't know the answer to that question.”

Considerations When First Becoming Fat Adapted

Interestingly, the late pathologist Dr. Joseph Kraft determined that about 80 percent of people with a normal glucose response have an abnormal insulin response — a condition he dubbed “diabetes in situ,” in other words, diabetes waiting to happen. He believed this diagnosis could predict who might develop Type 2 diabetes in the distant future, giving you a warning as early as 25 years ahead of time.

To determine your glucose and insulin responses, all you really need is an oral glucose tolerance test and a fasting serum insulin test. Should you find that you, like Newman, have diabetes in situ, becoming keto adapted (fat adapted through nutritional ketosis) is perhaps the easiest way to go about reversing it. While my book “Fat for Fuel” delves into nutritional ketosis and mitochondrial metabolic therapy in greater detail, here are a few helpful pointers:

  • Eat a ketogenic diet, high in healthy fats, low in net carbs with moderate amounts of protein
  • Make sure you’re eating enough salt. You need probably 6 to 8 grams of high-quality natural salt per day. When you're fasting, this is hard to do because you don't want to drink salt water. A workaround I use is to simply pour some Himalayan salt in the palm of my hand and lick it. I'll do that several times a day when fasting. This will help you avoid the so-called “keto flu,” which is nothing more than a sodium deficiency. Getting enough salt from your diet is typically not an issue while you’re on a ketogenic diet
  • To prevent much of the discomfort and side effects associated with the transition into fat burning, start by extending the time that you do intermittent fasting. Each day, gradually restrict your eating window until you’re down to four or even two hours. If you do that for a month or so, you're going to be burning fat, which will make the transition into a ketogenic diet rather easy and complication free

Fat Adaptation Helps Ease Transition Into Fasting

At present, Newman fasts five days every two weeks (and 22 hours a day on eating days, where his diet is ketogenic — 75 percent fat calories, mostly monos, eating from Dr. Steven Gundry’s Plant Paradox food lists; and fairly frequently eating a lot of resistant starches, especially on workout days. He is weight stable from fasting cycle to fasting cycle).

Once a year he also does a seven-day fast with his wife, who otherwise keeps to an intermittent fasting schedule where she fasts 16 hours a day. I currently water fast five consecutive days once a month. This is because most of the fasting metabolic magic of increased stem cells and autophagy doesn’t happen until after three full days of water fasting. However, I strongly recommend becoming fat adapted before making the transition into doing multiday water fasts. Newman agrees, saying:

“Before [you] just dive into a long fast, first I would suggest reading 'Fat for Fuel,' [and also] read Jason Fung's book ['A Complete Guide to Fasting']. If you're on medications, be careful. Really think about what you're doing, especially medications that affect your blood sugar.

This is powerful stuff. You can get into trouble … Arm yourself with knowledge. I’m well adapted … Even when I eat a fairly high carb meal, [my] beta hydroxybutyrate — the serum ketones — [are] still at a minimum 0.5, 0.7, 2.0 which is considered nutritional ketosis.

What I'm saying is I've been doing this for so long that my body makes ketones even if I'm not [eating strict low carb] … So, now I've transitioned into fasting. It's a natural transition for my body and I'm convinced that this is how our paleo ancestors worked — it was just a natural transition. It wasn't like, ‘Oh, if I'm out of ketosis for a day, I have go through a two week readaptation [into burning fat for fuel].’”

Water Fasting Is a Powerful Strategy to Optimize Health

There's enormous fear around water fasting. Many believe their body will go into starvation mode, resulting in all sorts of catastrophes, not to mention having to struggle with unrelenting hunger for days on end. The truth is, if you do your research and apply the strategies recommended in this interview, you’re not going to go into starvation mode; you’re going into health-generating mode. And you’re not going to be overwhelmed by hunger.

“As Fung [reveals] in his book, hunger's not on a linear upswing. It does come in waves but the longer you fast, generally the easier it gets. If you are keto adapted, then you really don't have the hunger issue to a great degree at all,” Newman says. I now see fasting as a process of health optimization because the benefits for fasting for four or five days is just extraordinary.

After reviewing Longo’s patents on fasting and fasting-mimicking diet (in which the protein is exclusively vegan and very low in sugar to avoid triggering specific nutrient sensing pathways), one of the things Newman noticed was that human subjects were not pushed into nearly as deep a fasted state as the animal subjects. “They always kind of were dancing around lightweight from my perspective with their human subjects,” he says.

By fasting five days out of every 14, Newman goes far beyond what most clinical practitioners and researchers will attempt, and his lab work provides strong anecdotal evidence that this intense kind of fasting does not impair health — it improves it. At the time of this interview, he had completed 13 cycles of five-day fasts every two weeks, and had not lost any muscle mass, and his bone density is that of someone half his age.

“I did a DEXA scan to get some objective evidence … I have a T score of zero [which] means you have the average bone mineral density of a 30-year-old of your sex. I'm 62 years old. If you had a +1, that would mean you'd have the bone density of one standard deviation above; a -1 would be one standard deviation below.

Then, on my body composition results, and this is for my all my limbs and everything, my body fat percentage was 16.7 … I'm not bodybuilder lean but I'm pretty lean. I checked my blood sugar in the afternoon and it was 31. This is the fifth day of a fast and my serum ketones were at 6 … I went to the gym, and [did a] super slow to failure workout …

I hadn't done one in about a month and I hadn't [worked out] on a fasting day, and I managed to increase my time under load by an average of 84 percent. Then I started doing that workout … every fifth day, [and] I've managed to incrementally increase my time under load largely every time on the fifth day of a fast, which I thought was interesting because I don't have any fuel on that day.”

Is Water Fasting Right for You?

Most people would likely benefit from longer water fasting, whether you’re overweight and diabetic or not. The key is to properly prepare yourself and not jump in half-cocked. At 62, and having a diagnosis of AFib, Newman is an inspiring example of how simple lifestyle strategies can turn your health around. In his case, he’s managed to keep his AFib largely under control with a combination of keto adaptation, fasting and magnesium supplementation.

Like George, most of you reading this are not medical or health professionals, and he really shows that if you have intelligence and persistence, you can read the literature and safely implement health strategies that can help solve the problem at its foundational core. Hopefully you'll consider integrating fasting into your self-help toolkit, because it’s really one of the most profound metabolic interventions I know of.

As an added boon, not only is it not going to cost you a penny, it’ll actually save you money because you won’t be buying food for a few days. As noted by Newman, “I would think that if the population would just do even like a 5-to-2 fast, where you're fasting two days a week as a general rule, if people did that it would probably change the health trajectory of the nation dramatically.” All of that said, there are several absolute contraindications. If any of the following apply to you, you should NOT do extended types of fasting:

  • Underweight, defined as having a body mass index (BMI) of 18.5 or less.
  • Malnourished (in which case you need to eat healthier, more nutritious food).
  • Children should not fast for longer than 24 hours, as they need nutrients for continued growth. If your child needs to lose weight, a far safer and more appropriate approach is to cut out refined sugars and grains. Fasting is risky for children as it cuts out ALL nutrients, including those they need a steady supply of.
  • Pregnant and/or breast-feeding women. The mother needs a steady supply of nutrients in order to assure the baby's healthy growth and development, so fasting during pregnancy or while breast-feeding is simply too risky for the child.

I would also caution you to avoid fasting if you struggle with an eating disorder such as anorexia, even if you are not clinically underweight. In addition to that, use caution if you're on medication, as some may need to be taken with food. This includes metformin, aspirin and any other drugs that might cause stomach upset or stomach ulcers. Risks are especially high if you're on diabetic medication. 

If you take the same dose of medication but don't eat, you run the risk of having very low blood sugars (hypoglycemia), which can be very dangerous. So, if you're on diabetic drugs, you must adjust your medication before you fast. If your doctor is adverse toward or unfamiliar with fasting, you'd be wise to find one that has some experience in this area so that they can guide you on how to do this safely.