Purpose: As Scientific AmeriKen has recently hit his 40th milestone the focus of research has taken a slight tilt towards the science of aging. One of the first studies to identify laboratory science can extend lifespan was one that showed calorie restriction extends the lives of mice. Fasting, although different than simply reducing caloric intake, is said to have life enhancing benefits as well - although others would argue that it could in fact be very dangerous. In this experiment, Scientific AmeriKen challenges many of the preconceptions surrounding fasting, by embarking upon a three-day, water only, post-Thanksgiving dinner fast.

Hypothesis: Fasting is said to impact anything from body fat and metabolism to the immune system and more. Due to this wide range of both potential good and bad impacts, Scientific AmeriKen will simply hypothesize that fasting will be a good thing. Although a reasonable rationale for this hypothesis would be that the human body is adapted well to fasting, as it is fasting and not constant feeding that was likely the norm throughout history of life on earth - However, the rationale for Scientific AmeriKen is just being hopeful that it is a good thing because he is about to do it.

Materials and Methods: Baseline measurements were initiated one week prior to fast. Fasting was initiated following engorgement on Thanksgiving day and proceeded through to the night of the third day (approximately 70-72 hours total fasting time). Fasting consisted of a water only diet (black coffee allowed on occasion). An allowance of one apple was given to wife due to lightheadedness. Measurements included body weight and body fat % (Electronic scale with bioimpedence analyzer (BIA)), waist, belly, and arm measurements (tape measure), and caloric input and utilization (MyFitness Tracker for diet tracking and Jawbone UP for calories burned). Body fat was also measured via skinfold caliper test. Finally, at each time point ScientificAmeriKen would complete as many push-ups as possible, take 60 seconds rest and repeat for a second set. One year and one week later, a second fast by ScientificAmeriKen was performed of similar length and conditions, although most data not kept.

Results and Discussion:

General impacts including body weight

Both ScientificAmeriKen and wife completed the three day fast. No significant issues occurred during the fast except a headache in wife that was alleviated immediately upon consuming an apple. Other minor symptoms include lightheadedness upon rising quickly and tunnel vision. It is possible that wife's failure to fully engorge oneself on Thanksgiving day led to her susceptibility and need for an apple. Many mysteries surround the potential impacts of fasting although one that is generally accepted is that fasting will result in significant weight loss. Figure on the right indeed shows this to be the case - however, a common warning regarding fasting is that this weight loss also comes with a reduction in one's "metabolism", thus resulting in chronic weight gain. Our data here suggests no such reduction of metabolism occurred and body weight generally returned to initial levels following the fast. Furthermore, one year later body weight remained the same for ScientificAmeriKen and reduced for wife. Examination of calories in / calories out (Figures below) support body weight data as little change was observed in calories out while a significant reduction in calories in happened during the fasting period, resulting in the expected weight loss. Like the body weight data, these data do not provide evidence of impacts on metabolism. However, these data also suggest a single 3-day fast does not work as a long term weight loss solution.

Impacts on metabolism and body fat

Another common belief is that fasting may first utilize lean tissue mass for energy instead of body fat. Furthermore, consistent with the notion above that metabolism declines due to fasting, leading to an expectation that body fat % would increase due to fasting. Instead our data below (figure bottom, left) reveal a significant decline in body fat due to fasting in ScientificAmeriKen, that did not fully return to baseline levels at the conclusion of this experiment. Body fat measurement was much more sporadic in wife with the greatest decline in body fat occurring after the fasting period. Although it is unclear where her baseline position was it does appear fasting resulted in a net decline in body fat %. Additionally, fasting also resulted in a roughly 5% decline in waist and belly circumference in wife, although no such decline was observed in ScientificAmeriKen (Figure bottom, right).

Impacts on muscle mass and function

As suggested above, warnings surrounding fasting include the possibility of loss of muscle mass and strength. To test this, measurements of bicep circumference were taken before, during and after the 3 day fast (Figure below, left). Essentially no noticeable change (i.e. change greater than 2%) was seen in either ScientificAmeriKen or wife. These findings are surprising considering ScientificAmeriKen was completing push-ups during this time, however, perhaps not to the extent that would lead to an increase in muscle size. Despite having no gain in bicep circumference, ScientificAmeriKen did increase the maximum number of push-up repetitions throughout the experiment, including during the fast period. Despite these gains, fasting seemed to dramatically affect the recovery rate from the exercise. Taken together, fasting did not seem to have significant impacts on muscle mass and strength.

Impacts on the immune system

A 2014 study found that fasting had dramatically improved the immune system (Link) and as ScientificAmeriKen was frequently sick (likely due to child initiating pre-school), he became motivated by this study to attempt this experiment. Surprisingly, both the number of times becoming sick (~3) and the duration of each illness, were dramatically reduced compared to the previous two years. However, during the follow-up fast one year and a week later, Scientific AmeriKen caught a cold - with the illness lasting a lengthy week and a half. In all it remains unclear if fasting is beneficial for ScientificAmeriKen's immune system.


One phrase to summarize the conclusion of this study would be, "what if you fasted for three days... and nothing happened...!". Indeed, within 1 week of completing the fast most parameters returned to baseline levels. Generally speaking, this phenomenon was similar in the female participant, with the exception of potential, but somewhat unclear, changes in midline measurements and body fat %. Yet, despite the apparent lack of impacts on body weight, a much more positive spin could be that fasting prevented the weight gain associated with thanksgiving gluttony. Although this finding is quite meritorious, fasting during this time comes at huge cost as wonderful thanksgiving left overs were accessible, yet frustratingly untouchable. To avoid this mental anguish, on the next fast attempt, ScientificAmeriKen performed the three day fast one week after Thanksgiving and found the process much easier to accomplish. As a final note, although the impacts of a single three-day fast did not appear to have long term impacts, it still remains unclear whether repeated or intermittent fasting could have the impacts discussed above. Nonetheless, ScientificAmeriKen nor wife have any desire to pursue this research further and will gladly await the pill form of these potential health benefits.

Questions, comments or want more discussion? Visit Science Chat Forum to to discuss this topic!

Download the raw data of this experiment.

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