Thursday, February 11, 2021

A Diet for the Human Holobiont.


A picture taken at an open-air market near Florence in 2015. As you see, overall, people are not fat in Italy. But that doesn't mean we don't have our share of obesity problems. 

The human holobiont is a wonderful machine that can do many things in many different ways. It has a "dual fuel" system that allows it to subsist on two main kinds of foods: one his carbohydrates, the other is fat. You probably know something about how switching to the fat-based metabolism can improve your health and reduce your weight. That's called the ketogenic, or "keto" diet

I won't go into the details. I just wanted to tell you that I am experimenting now with a relatively new version of the ketogenic diet, called sometimes the "pseudo-fasting" or "Fast-Mimicking Diet," developed by prof. Valter Longo presently at the USC university but, incidentally, born in Italy. 

The story of this and other similar diets is long, but the basic concept is always the same: you tend to mimic the way the human holobiont machine would work in its natural environment. There, it wouldn't normally have a 100% daily supply of high-energy content carbohydrates, from Corn Pops to ice cream. And, clearly, this kind of diet is not good for us for many reasons. Not only it makes us obese, but it also generates diseases such as diabetes, high blood pressure, high blood cholesterol, all that. It is called the "Metabolic Syndrome"

Recognizing the problem, led to several proposals to solve it: diets, mainly. One is the "paleo diet," others involve intermittent fasting. In all cases, you try to reduce the amount of carbohydrates you eat. The idea is to exploit the capability of your body to switch to use fat as an energy source. It is a different concept than that of the "standard" diets, which often consist of reducing calories without worrying too much about what kind.

At the basis of the ketogenic diets, there is the idea that you mimic a condition that your ancestors would normally encounter in their lives: that of running out of food. We store energy in the form of fat just as a precaution against that event. When we don't have enough carbohydrates, we can switch to fat and that makes us leaner and fitter. Our body "understands" that there is a problem and it moves to remedy it. Under the ketogenic regime, you are on the prowl. You are searching for food. 

So, how is the pseudo-fasting working? I can tell you about my personal experience. I am not obese, just moderately overweight. The main reason I am trying this diet is to reduce my blood pressure without using pills -- and all the typical problems you have as you age (I am 68): gastro-esophageal reflux syndrome, sleep apnea, pre-diabetes, if you are over 50 you know about that.  

The version of diet that I am following involves a reduced food intake: 40 grams of nuts and about 400 grams of vegetables per day -- plus a little olive oil (a must for Italians!). As I am writing this post, I am on the 4rth day of a 5-day cycle. It seems to work: I can see that I am in the ketogenic mode using "keto sticks." I've lost about two kgs, so far. Not much, but it is something, and I am still halfway through the cycle. And my blood pressure is going down, nothing dramatic, but a little, yes. 

What I think is interesting is how the pseudo-fasting diet is a relatively easy diet to follow. In the past, I had tried the alternate fasting diet, you fast one day and you eat normally the other. It is fine, but I found it a little harsh. At least for me, pseudo-fasting was much easier: a little hungry the second day, but no problems the other days. The beauty of the idea is that you don't separate yourself from the rest of your family at mealtimes. You eat with them, although, of course, you eat very little and food of low nutritional value. 

I also think it is important that this diet is not made to punish you by making you hungry. We tend to think that our ancestors were primitive brutes and would go hungry all the time. No, not at all. As Chuck Pezeshki explains, humans are social animals and tend to share food. There must have been times harder than others, but hunger must have been rare, just as over-abundance. Hunger and obesity are maladies of what we call "civilization." So, I think the pseudo-fasting diet does mimic something that our ancestors would experience: periods of scarcity where they had to cope by being smart and efficient and make the best use of their (our) dual-fuel metabolic system.

Then, of course, I am experiencing the same sensations that I had with the more conventional fasting. All sensations that are part of the evolutionary tools you have inherited from your ancestors: you feel more tired, but also more alert. You tend to conserve energy, but you are ready to go into running mode if you see a potential steak in your hunting range. Or, more likely, edible berries not so far away. A peculiar sensation is the different range of vision. Somehow, I tend to detect things at a larger distance, noting details that I don't normally note. I don't know if this is common, but it makes sense: if you are on the prowl, then you have to be alert for any possible food source, even a distant one. 

Then, of course, when you are on a diet, you tend to dream of eating good things! But I figure that it is normal. I woke up this morning while dreaming of caviar and champagne. Yes, like James Bond and Vesper Lynd in "Casino Royale." A diet that gives you this kind of dreams must have something good in it!

So, how does that relate to the concept of holobionts? Well, it is because you shouldn't forget that what keeps you alive is a large number of little creatures inside your cells: the mitochondria. They are the source of energy for everything we do, but, remarkably, they don't share your genetic code. Their DNA is just theirs, you inherit them from your mother and not from your father. For some reason, when the female ovum is fecundated, the mitochondria carried by the male spermatozoa are destroyed and disappear forever. So, mitochondria are creatures living inside the human organism. They are a perfect example of symbiosis: they couldn't live without you and you couldn't live without them! That's how holobionts function. 

And we keep going. Who knows? One day we could find a way to stop the obesity epidemic that's making so many people sick and unhappy in the world. Onward, fellow holobionts!

To go more in-depth, do read this wonderful post by Chuck Pezeshki. And thanks to Dr. Alberto Santini for having placed me on the pseudo-fasting track!


  1. In The Plant Paradox author Dr. Steven Gundry writes that the mitochondria are chronically overworked "trying to handle that huge number of calories you eat, day in, day out, 24/7, 365 days a year ... when your mitochondria are under this kind of strain, your energy sputters to a stop ..." He goes into more detail and also recommends a keto diet.

  2. You could try hand grip exercises to reduce BP; it's surprising but it seems to work:



Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)