A Man does Total Fasting for 40 days (medically supervised) – Inside of an 1890 Experiment

A Man does Total Fasting for 40 days (medically supervised) - Inside of an 1890 Experiment


On March 17, 1890, Giovanni Succi, a 37 year old lean Italian, embarks on a 40-day dietary experiment during which he will consume no food, but drink mostly filtered water. Nothing out of the ordinary for him, as he claims to have successfully completed 32 fasts “varying from 20 to 30 days each, but never so long as 40” [1].

Signor Succi, as he was known in his circles, was 5 feet 5 inches tall (~165 cm) and weighted 126 lbs (~57 kg) at the beginning of his fast. That’s quite lean, if not skinny, by modern-day judgment.

How can such a lean person go without food for so many days, while most of us nowadays think we’re gonna get sick if we don’t eat multiple meals everyday? The irony, I think, is that’s the exact reason we’re getting sick: too much food too frequently, regardless of the dietary protocol. We are obsessed by food consumption and biased by diets.

In any case, Succi was supervised by 4 medical men: Mr. George Robins and Messrs. Powell, Burt, and Pike. The full report was published in The British Medical Journal on June 21, 1890 [1]. Now, let’s get into the specifics of the experiment, as it is exposed through the scientific perspective of that time.

Succi fasts for 40 days – Daily Reports

March 17th

Last meal was at 3 P.M. The physiologists and physicians consulted and measured him, reporting that Succi appeared to be in perfect health. 31 hours after meal he complained of feeling hungry and a slight epigastric pain. “To relieve this he took a few drops of his elixir in water with good effect” [1].

Mr. Robbins reveals what the elixir was [1]:

During each day also he took a small quantity of an elixir, on an average less than sixty drops per diem, in doses varying from 5 to 20 drops, in water. This he took as a sedative to the stomach, and to relieve slight colic or flatulence, from which he suffered somewhat at times. It resembled chlorodyne in composition and effect, with the addition of a bitter, probably gentian, and capsicum, but nothing of a nutritive character has been detected in it…

I would assume the hunger Succi felt can mostly be attributed to glycogen depletion, as the body gradually shifts to relying on fatty acids and ketones for energy.

March 20th

In the third day of the fast, Succi felt comfortable, he slept well and had no desire for food.

March 27th

At this point, Succi had lost 16 pounds, and besides appearing emaciated (abnormally thin), he felt fine, was not hungry, had regular pulse and his temperature was 97.6 degrees Fahrenheit (36.4 degrees Celsius).

March 30th

According to the report, Succi consumed 12 oz (~350 ml) of warm water to clear his stomach of “bile” and to “relieve the parched condition of his mouth and foulness of breath” [1]. He vomited 13.2 oz of a clear (pale yellow) liquid, containing no trace of solid food.

Next day he repeated the experiment, adding some Hunyadi Janos water (salty medicinal water used for colon cleansing), causing an evacuation of “a meconium-like fluid, containing also a very small quantity of solid matter”. It’s amazing how much time food can stay inside the system.

April 6th

Half-way through the experiment, Succi had lost 22 pounds in weight (~10 kg), but he was feeling good.

“The heart sounds, though feeble, were quite regular and natural; the lungs were resonant, and admitted air freely. His mental capabilities and special senses were in no way impaired.” [1]

April 16th

It was day 30 of his fast and Succi had lost 28 pounds and 12 oz (~13 kg). His heart was still beating regularly, but he slept badly and felt anxious because he never experimented with total fasting for more than 30 days. And he still had 10 more days until completion. However, two days later, his anxieties were gone and he was very confident to take the experiment to a successful exit.

April 26th

During the last day of his experiment, Succi felt excited and rather irritable, but in very good health given the experiment to which he subjected himself. His pulse was fairly firm and regular and his heart sounds were, though delicate, distinct. The total weight loss was 34 pounds and 3 oz (~15.5 kg). You can imagine his physical appearance. πŸ™‚

As written in the report [1]:

It is a remarkable fact that from the first day to the last, Succi did not develop a single alarming symptom, or experience any great amount of discomfort. Even during the first few days, when the pangs of hunger might have been expected to assert them-selves most acutely, he made no complaint, but in reply to questions, said he felt very comfortable.

Other than his elixir and the medicinal water, Succi smoked 1 or 2 pipes everyday, and sometimes a cigar or cigarette (he was rollin’ πŸ™‚ ). I believe this was part of his reward mechanism that you will learn about in my book Periodic Fasting.

Realimentation after the 40-day Fast

In the first day, Succi consumed a half a pint of beef-tea.

Between this time and noon the next day, he took only beef-tea, prepared rice, beef-peptone, three small oranges, and about 1-2 pints of water“. He gained 1 pound in weight. It’s not what I would call the best realimentation strategy, but it worked and still works for many experienced faster. In the upcoming book I talk about maintaining ketosis before and after fasting, which is not in line with the strategy used by folks.

In the second day, he consumed more of the same stuff, but in larger quantities, while in the third day he started adding fish “which caused a feeling of dizziness and some pain in the epigastrium”. I believe his reinvigorated digestive system was learning to process food once again.

13 days after the fast and Succi was rapidly gaining weight. He regained 22 pounds and 8 oz (~10 kg) and his physical appearance was dramatically improved [1]:

He was now beginning to take ordinary food in combination with the other articles mentioned, and except that he had still nearly a stone to recover, did not seem any the worse for the privations he has undergone.


Succi’s recuperation was complete and it happened fast, marking an unimpaired integrity of his absorptive and digestive systems. It’s interesting to note that he started artificially heating his room, once he experienced that his weight loss is reduced in warm climates.

Is this one of the early scientific mentions of the efficiency of cold thermogenesis in weight loss?

Urea excretion, higher initially, gradually decreased thereafter, marking a lower contribution of muscle catabolism to the energy demands of the subject. At some points during the fast it either increased or decreased, according to the level of physical activity that Succi was exposed.

As the physicians point out, Succi’s muscular power suffered but little. “The electrical reactions of the muscles showed nothing remarkable” [1].

Nothing remarkable may be translated as: nothing statistically significant compared to the pre-fast measurements. Physical, blood, urinary, and other measurements can be analyzed in detail in the tables contained in the article [1].

Investigators finished their analysis on Succi’s experiment by concluding [1]:

We think, then, that it is fairly proved that the body may be deprived of food for a considerable period and yet remain in a condition of health, a fact which may be put to some use in practical therapeutics; it also has a direct bearing on the question of rectal alimentation. In case of severe dyspepsia, or gastric ulcer, and in the surgery of the abdominal cavity and alimentary canal starvation would seem to be a perfectly rational means of treatment while it is worthy of trial in obesity and in fatty and other tumors.

Rectal alimentation = ? say what? Fecal Transplants?

These guys were thinking way beyond their times…

If Succi and other lean individuals can successfully fast for 40 days, while obese individuals can go for 139, 236, and even 382 days without food (I talk about them in Periodic Fasting), then what about you and me thinking we’re gonna die if we don’t eat every couple of hours?!


1. The British Medical Journal. (1890). The fasting man. British Medical Journal, 1(1538), 1433–1450.

Photo: The British Medical Journal

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12 Responses to A Man does Total Fasting for 40 days (medically supervised) – Inside of an 1890 Experiment

  1. Karl Goldkamp says:

    Looks like you found your next topic. Nice. By the way, FMT goes way back. There’s reference to it being used in in traditional chinese medicine 400 ad.
    Look forward to reading the book.

    • Chris Chris says:

      Karl, yes, it’s been widely used…it’s just that fasting is unpopular because people cannot go beyond the glycogen depletion intense hunger. but ketosis mitigates that situation making the transition smooth and un-perceivable. that’s one of my strategies that I talk about in the book πŸ™‚

      • Janet says:

        Hey Chris,

        I found this article very interesting. I was one of those people that thought I would die if I did not eat every couple of hours because I had physical symptoms ( Headache, cranky ) since starting LCHF I have been stretching my time between meals and I can’t believe it. Yesterday I ate breakfast @ 8:00 and did not eat again until 7:00 pm. I had a busy day, my mental clarity was great and I had great energy level all day. Slept well and started it all over again.


  2. Sylvia says:

    “In the upcoming book I talk about maintaining ketosis before and after fasting, which is not in line with the strategy used by folks.”

    That’s interesting, because in majority of resources related to fasting the authors (like G.P. Malachow) advise drinking fruit juices and eating fruits before/after longer periods of fasting. It is usually claimed that eating anything like meat and fat would make you sick/ cause some serious problems. But on the other side, I believe fruit juices are bad for pancreas, raise blood glucose and definitely kick somebody out of ketosis – while it is deep ketosis that seems to cause the benefits fasting gives.
    As I got interested in fasting some time ago I was wandering how to do such a long fasting safely and without those fruits/ staying in ketosis.
    Must read your book.

  3. kateryna says:

    Great article. A Canadian nephrologist, Dr. Jason Fung (https://www.youtube.com/watch?v=FcLoaVNQ3rc), recommends a fasting protocol to his diabetic/obese patients to eliminate their insulin resistance, among other ills. He usually gets them off their diabetic meds in no time at all. I agree with you that fasting is a wonderful tool to regain health.

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