Data from David Blaine’s 44-day Fast – [Metabolic and Physiologic]

David Blaine - Macro and micronutrient looses Study - 1


David Blaine has subjected himself to a prolonged fasting experiment lasting between Sept. 5 and Oct. 19, 2003.

“A 30-year-old male, weight 96 kg, height 1.84 m, entered a transparent Perspex box on the banks of the river Thames in London and was suspended in the air from a crane for 44 days. During this period, he took only water to drink.” [2]

At the end of the fast, Blaine had lost 24.5 kg and ~8 BMI points (29 => 21.6). Though his BMI was not life-threatening, he was admitted to the hospital for intensive and careful refeeding, as some of his biomarkers were out of normal limits. [1]

Several research studies have been published based on Blaine’s self experiment. Let’s see some data…

David Blaine’s 44-day Fast

In terms of body composition progression [2, 3]:

David Blaine - Macro and micronutrient looses Study - 2

David Blaine - Macro and micronutrient looses Study - 5

“Total energy expenditure was estimated to be 1638–2155 kcal/d of which 13.0–17.1% was from protein oxidation.” [3]

They used three methods to estimate energy expenditure (TEE).

– method 1: 1638 kcals/day
– method 2: 2155 kcals/day
– method 3: 1736 kcals/day

Average BMR (basal metabolic rate) was estimated at 1578 kcals/day. For precise details see study [3].

It would have been great if rather than estimating, they would have measured his BMR and TEE. Similarly, they used skin fold measurements to estimate his body comp. changes, which is also inaccurate by modern means.

David Blaine - Macro and micronutrient looses Study - 6

Blaine’s muscle mass loss was 10.4 kg, estimated from creatinine excretion. [3]

Urine volume was above 3 liter (3L) per day. Daily urine tests measured: glucose, ketones, pH, nitrite, pH, bilirubin, and a few other markers. [3]

“Total N loss during the entire 44-d period was calculated from cumulative urine N loss plus fecal N loss (assumed to be 6 g of N during the fast, resulting from four bowel actions) and other miscellaneous losses including those from skin (assumed to be 5 mg of N/kg of lean body mass per day during fast).” [3]

As Jackson et al. (2006) describe:

“DB, who was initially a muscular looking man, was visibly thinner on exit from the box. His blood pressure taken almost immediately before the event began was 140/90 mmHg while lying and 130/80 mmHg while standing, and at the end it was 109/74 mmHg while lying (pulse 89 beats/min) and 109/65 mmHg while standing (pulse 119 beats/min).” [3]

As his experiment went on, Blaine felt weaker. Two weeks in and onward he experienced faintness and dizziness upon standing up quickly, which is often reported by people who fast for long periods of time.

“He also developed transient sharp shooting pains in his limbs and trunk, abdominal discomfort, nausea, and some irregular heart beats.” [3]

Metabolic Progression

Here’s a picture of some biomarkers at the end of the fast – day 0 of refeeding [2]:

David Blaine - Macro and micronutrient looses Study - 3

And here’s a bigger overview [2]:

David Blaine - Macro and micronutrient looses Study - 4

Blaine went into a hypocaloric refeed for the first three days. They used a liquid formulation called Ensure Plus (220 ml/carton), which delivered:

330 kcals: 44.4g carbs (12.7g sugar), 10.8g fat, 13.8g protein

It also contained: 11.5 mmol Na, 11.3 mmol K, 6.4 mmol Ca, 6.5 mmol PO4, 2.7 mmol Mg

The refeeding strategy was as follows [3]:

Day 0: Overnight, 2 cartons + water (ad lib.)
Day 1: 2 cartons + water (ad lib.)
Day 2: 5 cartons + water (ad lib.)
Day 3: 6 cartons + water (ad lib.)
Day 4: light diet of 1,500 kcals
Day 5: ad lib.

Even though Blaine was keen to eat immediately after getting out of the box, he understood that he has to go through the careful refeeding strategy. From Blaine’s diary [3]:

Day 1: experienced cramps and “was not yet ready to eat but the thought of chewing and tasting again was so strong”.
Day 2: continued experienced cramps, started craving food
Day 3: “I could not help it; I wasn’t hungry but just wanted to eat once again”.

That’s interesting. Am I missing something? Craving != hungry ?

Day 5: “my hunger grew out of proportion and I was eating almost a double portion of all meals”.

As per the researchers: “the high 3-hydroxybutyrate concentration measured could contribute to low appetite on the first few days.” [3]

Some out of range biomarkers at the end of the fast [1]:

– slightly low K – 3.3 mmol/L
– high B12
– high Zn
– abnormal liver function
– high IGFBP1
– high GH
– low-normal insulin
– very low IGF1
– high cortisol
– low leptin and ghrelin

PYY, AgRP, Alpha-MSH, NPY, and POMC (hunger markers) – not substantially different from those measured in subjects after overnight fasting.

“Blaine’s sensation of hunger, which he did not have during the first few days, increased considerably on day 3; this increase had been immediately preceded by an elevation in plasma levels of orexin A and resistin, an observation of unclear relevance, given the available data.” [1]

Some of his nutritional and metabolic deficiencies required supplementation in the following manner [3]:

– 50 mg thiamine twice/day
– 80 mg niacin
– 8 mg vitamin B6
– 8 mg vitamin B2 and 20 mg vitamin B1 daily
– 5 mg folic acid/day
– Forceval capsules (vitamins and trace elements), 1 capsule twice/day
– 24 mmol effervescent KCl 3 times/day for 2 days and then 12 mmol 3 times/day


Data should speak for itself. My additional comments are not necessary. David Blaine is no stranger to outstanding experiments of will. And since we’re dealing with data from his n=1, it would be appropriate to let him do the ending:

“I think to be able to survive something like this proves that we can live with nothing…Everybody wants domination, wants to own and control everything and believes that money and diamonds and riches and all this stuff is what life is about, but, you know, at the end of the day that really means nothing…there is no value in that.” [*]


  1. Korbonits, M., Blaine, D., Elia, M., & Powell-Tuck, J. (2005). Refeeding David Blaine—studies after a 44-day fast. New England Journal of Medicine, 353(21), 2306-2307.
  1. Korbonits, M., Blaine, D., Elia, M., & Powell-Tuck, J. (2007). Metabolic and hormonal changes during the refeeding period of prolonged fasting. European Journal of Endocrinology, 157(2), 157-166.
  1. Jackson, J. M., Blaine, D., Powell-Tuck, J., Korbonits, M., Carey, A., & Elia, M. (2006). Macro-and micronutrient losses and nutritional status resulting from 44 days of total fasting in a non-obese man. Nutrition, 22(9), 889-897.

Images: here, here, and here

Get on my list of friends
More about my book Persistent Fat Loss
More about my book Ketone Power
More about my book T-(Rx)
More about my book Periodic Fasting

Related posts:



6 Responses to Data from David Blaine’s 44-day Fast – [Metabolic and Physiologic]

  1. mikhail vulkov says:

    “– 8 mg vitamin B2 and 20 mg vitamin daily”
    What vitamin is 20 mg?

  2. Shaun says:

    Thanks for posting this.

    I was surprised by the results to say the least.

    Based on this sample size of 1,..

    1) 24.5 kgs lost had only 6.3 kgs of fat. Rest was lean mass.

    2) Fat percentage dropped from 20.1 to 18.1. This 2% drop after 46 days of fast is nothing to call home for

    3) On day 236 of refeeding, all fat loss was regained and then some more. Fat percentage went from 20.1% to 21.9%.

    On that same day however, there was still 5.2 kgs of lean mass lost. Prefast, david has 76.7 kgs of FFm. On day 236 of refeeding, he had 71.5 kgs of FFM only.

    4) His BMR went from 2047 prefast to 1989 on day 236 of refeeding

    So one can say that this fast was harmful to david metabolism.

    In addition, Glucagon shot to the roof. It went from 4.83 prefast to 30.03 on day 236 of refeeding! Note however that it was 4.88 on day 46. Were there any values taken between days 46 and 236?

    I like that his FBS was 4.5 both on days 46 and 236.

    Do we know whether his blood pressure remained at ideal range at refeeding day #236?

    Thanks again for sharing. I find this quite fascinating.

    • Chris Chris says:

      I’m not sure if this was harmful or not to him. I think it’s more clear that a lot of was estimated, and not calculated, which may lead to less accurate results. I didnt find data on BP at day 236.

      • Grant G. says:

        I tend to agree about the accuracy. Taking the nature of estimation into account and the innaccuracy of skin tests for Body Fat, this is really more anecdotal in my opinion. I think his journal and quotes are the more interesting part. There is plenty of data about extending fasting and the health benefits, for example, here is a paper that tracked a man on a 382 day fast:

        He was totally fine when he came off the fast and regained a negligent percent of body fat back.

    • Blaine says:

      Shaun imo, reason why so much lean mass vs fat was lost was due to no adequate weight training etc. If the body starves itself it will eat into the muscle heavily, that is why it is recommended you lift weights as you cut down your weight, otherwise you will lose weight overall but your body composition will remain the same if you have surplus fat.

Leave a Reply

Your email address will not be published. Required fields are marked *