September 18, 2025, 2:03 am | Read time: 8 minutes
FITBOOK author Beke Enderstein conducted a self-experiment with intermittent fasting using the “Alternate Day Fasting” method. Unlike the 16:8 diet or the 5:2 variant, this involves fasting for 36 consecutive hours followed by 12 hours of unrestricted eating.
After “16 to 8” and “5 to 2,” It’s Now “36 to 12”
For four weeks, I focused on one of the toughest intermittent fasting methods: the so-called alternate fasting, where I abstain from food for 36 hours, followed by 12 hours of unlimited eating.
This form of intermittent fasting is also known as the “Every Other Day Diet” and was introduced by Prof. Dr. Krista Varady, who published a book of the same name in 2013. It’s important to note that Krista Varady is a professor of nutrition at the University of Illinois and conducts extensive research on intermittent fasting. Both the expert and other studies, such as one published in 2005 in “The American Journal of Clinical Nutrition,” have shown that alternate fasting is an effective weight loss strategy for overweight individuals.1 I will refer to the intriguing results of the 2005 study frequently throughout the text.
The Golden Mean: Maximum 500 Calories!
As with the “5 to 2” diet, where fasting occurs two days a week, the “Every Other Day Diet” theoretically allows up to 25 percent of the usual energy intake on fasting days. With an average caloric need of 2,000 calories, this amounts to about 500 calories.
To maximize the health benefits of fasting, I initially planned a zero-calorie diet during the fasting phase of my “Alternate Day Fasting” self-experiment. However, if my gut feeling indicated that a small meal would be beneficial, I allowed myself a buffer.
An Important Nutritional Psychology Note
For individuals with eating disorders, any form of fasting and dieting is off-limits! The same applies to those who want to starve themselves only to binge on fast food, ice cream, and the like for a whole day. The focus is on the conscious decision to give the body and mind a break—and lose a few pounds in the process!2
Accordingly, the figure-friendly “Alternate Day Fasting” is suitable for anyone who wants to benefit healthily and mentally from fasting—alternating with balanced, nutrient-rich, and wholesome meals on eating days.
Note: Fasting beginners should initially choose less strict fasting variants like “16 to 8” to gradually get used to longer meal breaks.
What Did I Expect from My “Alternate Day Fasting” Self-Experiment?
Since I have already detailed the health benefits of intermittent fasting from A for anti-aging to Z for cell protection in parts 1 and 2 of my intermittent fasting guide, I will keep it brief here.
My Goals
- Weight Loss: According to study results, “eat stop eat” even in the milder version with up to 500 calories on fasting days leads to a significant reduction in fat mass with an average weight loss of 5 kilograms in the first month. I found this aspect particularly interesting because, for example, I did not lose more weight during therapeutic fasting (completely without solid food!).
- Health Improvement: Due to the numerous health benefits, I have become an absolute fasting fan. The focus is on the so-called autophagy (cell cleaning). Additionally, blood values improve with “Alternate Day Fasting,” and insulin levels are lowered.
I was also curious about how easy or difficult it would be for me to eat nothing or a maximum of 500 calories for 36 hours.
My Intermittent Fasting Plan “Alternate-Day Fasting”
To avoid feeling tired and low on energy on fasting days despite the lack of food, I put together a large assortment of drinks. It is recommended to drink two to three liters of fluids during alternate fasting.
Suitable Drinks
The basis of my fluid intake was mineral water and tap water in the form of herbal teas like peppermint, lemon verbena, and sage. “On top” were moderate amounts of green and black tea mixed with mate tea—naturally pure, without sugar or milk.
Meals on Eating Days
On eating days, I ate as I would on “normal” days: This included two to three nutrient-rich main meals, which I supplemented with salad or raw food as a starter and berries, frozen yogurt, and the like as dessert. On days when I skipped breakfast à la 16:8, I ensured that lunch and dinner had a particularly high nutrient density.
In general: Since there are no dietary rules for eating days in “Alternate Day Fasting,” they can be arranged flexibly.
Theoretically, one could eat whatever and as much as one wants. However, for me, this does not align with the fasting philosophy. I value a wholesome diet, especially since I consume few or no essential nutrients on fasting days. Nevertheless, I allowed myself chocolate, gummy bears, salty licorice, or a glass of red wine on eating days if I felt like it.
Fasting Days with 500 Calories
As described above, I initially tried to go 36 hours without eating. However, knowing from experience that I crave a delicious meal in the evening, I planned to enjoy a small dinner depending on my gut feeling—on individual days or throughout the entire period.
Fasting Recipes
My Fasting Plan
- Week
- Monday: 1st fasting day (including night from Sun to Mon)
- Tuesday: 2 to 3 main meals without calorie counting
- Wednesday: 2nd fasting day (including night from Tue to Wed)
- Thursday: 2 to 3 main meals without calorie counting
- Friday: 3rd fasting day (including night from Thu to Fri)
- Saturday: 2 to 3 main meals without calorie counting*
- Sunday: 4th fasting day (including night from Sat to Sun)
*particularly nutrient-rich thanks to a starter and dessert
I planned the second, third, and fourth weeks in the same pattern.
My Experience: Four Weeks of “Alternate Day Fasting” in Self-Experiment
After not eating for 36 hours on my first fasting day, I quickly realized that I would definitely prepare a small dinner on each fasting day.
Since the 500-calorie meal on fasting days does not hinder the health benefits and weight loss of “eat stop eat,” according to Prof. Dr. Krista Varady, I would also recommend everyone to prepare a nutrient-rich meal within the fasting phase.
Motivation
My tip: The mindset plays a significant role in sticking to fasting. Psychologically, it makes a big difference whether I start the fasting day with the thought “no food today and overnight until tomorrow” or “I’m looking forward to a delicious meal in the evening.” If you still want to try a 36-hour zero-calorie diet, you can also come up with a suitable motivational phrase.
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My Conclusion on Alternate Fasting
For me, as an experienced intermittent fasting fan, it was significantly easier to persevere thanks to the 500-calorie meal and motivating thoughts! This assessment also aligns with study results, which show that the feeling of hunger decreases with a small meal on fasting days—and the chances of staying on track increase.
The experience that my body adjusts well to two meals (16:8) or just one dinner (5:2) was a clear advantage for my self-experiment with “Alternate Day Fasting.”
Weight Loss
At the end of the fourth week, my scale indeed showed almost five kilograms less. Therefore, I would absolutely recommend “eat stop eat” to overweight individuals who want to lose weight sustainably and long-term, provided there is no eating disorder like binge eating. Scientific studies also show that “Alternate Day Fasting” is effective for overweight but not for obesity (compulsive overeating).3
The rapid weight loss in the first few weeks will decrease over time. However, this aspect is important because successful weight reduction should not happen too quickly. The body and psyche need sufficient time to adjust to the new body feeling and to learn permanent healthy eating behavior.4
Everyday Suitability
I also positively rate that calorie counting on eating days is eliminated, and the 500-calorie meals on fasting days are easy to put together with some practice. This makes alternate fasting suitable for everyday life and uncomplicated. Meal invitations and the like should, of course, be scheduled for eating days as much as possible.
I also like that individual preferences are taken into account. This makes this fasting method practical for people with allergies, food intolerances, and for vegetarians and vegans.
My Summary
I consider “Alternate Day Fasting” with a nutrient-rich food selection a sensible weight loss strategy. In my opinion, “eat stop eat” is preferable to any crash diet, considering current dietary recommendations. Initially, however, those looking to lose weight should slowly ease into intermittent fasting.
For individuals who are of normal weight or only slightly overweight and primarily want to benefit healthily from everyday fasting, “lighter” variants like the “5 to 2” diet should suffice.
Personally, I have decided to stick to my “16 to 8” method three days a week in the coming months. On the remaining two weekdays, I will maintain fasting days with an evening meal in line with “5:2” or “Alternate Day Fasting.” And most importantly: weekends and vacations will continue to be marked by culinary freedom. I will enjoy brunch, dining out, or cooking with friends extensively.