I recently came across this study from 1973 in which a 27 years old male has fasted for 382 days under the supervision of researchers from a Scotland University. This is the longest fast ever been recorded.
This patient weighted in 456 pounds (~207 kg) and weighted out 180 pounds (~82 kg). So, he lost 276 pounds (~125kg) during his fast. Five years after the fast ended, the patient’s weight has been constantly around the values of 196 pounds. A.B. had no ill symptoms during and after the fast.
Throughout the entire period of 382 days, patient A.B. consumed water and had taken vitamin supplements, yeast for the first 10 months, potassium supplements (Day 93 to Day 162), and sodium supplements (Day 345 to Day 355). Urine and blood collections were taken throughout the whole period of fasting. Fecal evacuations were infrequent in the later period of the fasting, as the time between stools was averaging from 37-48 days, as the researchers claim.
Blood glucose decreased progressively in the first four months but it remained at 30mg/100ml onward. However, by the end of the fasting, the researchers have frequently seen values below 20mg/100 ml. The researchers say that “despite the hypoglycemia the patient remained symptom free, felt well and walked about normally”. Here’s the average monthly blood glucose level:
The researchers have also tested for glucose tolerance and they reported unimpaired capacity for glucose uptake.
Here’s the mean monthly plasma electrolytes concentration:
During the first four months there was a decrease in serum potassium concentration, which is why they administered potassium supplements for the next 10 weeks, which have increased the K levels. After that period no further potassium supplements have been taken, as K serum levels remained normal.
There were no further decreases in potassium levels probably because there was a sufficient release of potassium from the fat cells to make up for the excretion of potassium through urine.
Hypercalcaemia has been observed for certain periods within the last 6 months of the fast, but that spontaneously remitted in the last month of the fast.
Plasma urea decreased in the first two weeks but it then remained constant onward at 15-20mg/100ml.
Plasma uric acid, which was high before the fasting, remained constant during the fasting.
Cholesterol levels were constant at 230mg/100ml and they have increased at 370mg/100ml during the refeeding period. I’m curios to know what the subject consumed in this refeeding period.
Here’s the graph with plasma magnesium levels for the entire period:
Serum magnesium levels decreased in the first few weeks but they remained constant until the end of the fasting. During the refeeding period, plasma magnesium levels achieved normal range.
Urinary electrolyte excretion increased in the first 300 days of the experiment but then it decreased as it can be seen in the graph below:
Blood ketones were detectable throughout the entire period of prolonged fasting. Too bad they don’t have a graph for these as well.
A.B. lost 276 pounds during his 382 days of fasting. This is an average of 0.72 pounds per day (~330g), which is mostly attributed to the breakdown of fat tissue. I think that we can achieve significantly high levels of fat-oxidation while being keto-adapted without having to reach out for such extreme measures.
In the graph above, Jeff Volek (University of Connecticut) talks about peak fat oxidation. He says that ultra-athletes (not-ketoadapted) can oxidize 1g of fat per minute (the maximum observed value) during high-endurance exercise. Not-ketoadapted means that these athletes are not adapted to burn fat as the primary source of fuel. This means that such a high-caliber athlete can burn 60g of fat during one hour of a marathon.
On the other hand, keto-adapted ultra runners (observed by Jeff Volek) have reached 1.8g of fat oxidation per minute. This is more than double the rate of fat oxidation/minute that non-ketoadapted athletes can reach. So, in an hour a keto-adapted athlete would burn more than double the amount of fat compared to non-ketoadapted counterparts.
To not move away from the subject, the researchers from the 1973 fasting experiment conclude that this was a successful experiment as A.B. was able to maintain his weight (~196 pounds) for at least 5 years since the fast has ended.
They correlate the study with other successful total starvation experiments up until that period of time (1973). They also refer to the 5 reported studies where the subjects died in the first few months of total starvation (either of lactic acidosis, heart failure, bowel obstruction, or during the refeeding period). Several of these subjects have not been labeled “healthy” before beginning the total starvation experiment.
This study suggests that the human body can adapt to total starvation for pro-longed periods of time as longs as the body fat reserves are substantial enough and as long as the subject is supplemented with vitamins, minerals, and of course water.
Even though A.B. was not hospitalized for the entire period, I think that the success of total starvation therapy strictly relies on the careful monitoring of the patient because complications can appear during the experiment.
And some of us who are very carbohydrate dependent would kill for food if they don’t eat for a couple of hours.
1. Stewart, W. K., & Fleming, L. W. (1973). Features of a successful therapeutic fast of 382 days’ duration. Postgraduate medical journal, 49(569), 203-209.
2. Jeff Volek – The Many Facets of Keto-Adaptation: Health, Performance, and Beyond.
3. Stephen Phinney and Jeff Volek – The Art and Science of Low Carbohydrate Living