1. (2019) Body Composition Changes Following Lenten fasting: A Study in Ethiopia by Tariku Sisay, Getahun Chala, Yonas Teshome, Chala Kenenisa Edae, J Nutrition Fasting and Health.
2. (2020) Changes in biochemical parameters by gender and time: Effect of short-term vegan diet adherence by Tariku Sisay, Tesfaye Tolessa, Wondyefraw Mekonen, PLoS One. 2020; 15(8).

   Excerpts from the above paper:

   "The Ethiopian Orthodox Church (EOC) specifies dietary limits and fasting for the total number of 250 days each year, of which about 180 days are compulsory for all. These fasting practices are performed on every Wednesdays and Fridays, and the entire Lenten season [13]. To the EOC, Lenten is a test of one's Christianity with greater rigor than any other fasting that encompasses 56 days. During the lent fasting most of the EOC is considered as "vegans", since meat, eggs, dairy, and honey are restricted. Other lifestyle behaviors (for example., alcohol use, and smoking, sexual) also restricted specifically during Lent [13]."

   What do they eat during the 180 days of dietary fasting (every Wed & Fri and during the entire length of 56 days of Lent)? Traditional Ethiopian vegan preparations without processed foods:

   "The vegan diets that consumed for the entire 7-weeks of the EOC Lenten were purely a plant based diets that involved whole grains, cereals, green leafy vegetables, legumes, peas, beans, fruits [13]. A local stew (wat) that scooped up with enjera (sour flatbread made with teff, a tiny, round grain) is the habitual foods of EOC during Lent. The particular stew is Shiro wat (made from chickpea, broad bean flour, mixed with garlic and onions, and made into a thick, just like a paste), miser wat, or red lentil stew and Salata (Ethiopian salad)."

   During non-Lent days, 40% calories were meat & fish, 18% were dairy, 25% were cereals and whole grains, 9% were veggies, 8% fruits. During Lent days, they had zero meat & fish, zero dairy, 46% whole grains, 29% veggies and 25% fruits.
   

   They studied the effects of 56-days of veganism (without processed foods) during Lent. Myriad health markers improved but when they reverted to their original diet after Lent was over, their markers started becoming worse.

What's the relationship between fasting guidelines in Ethiopian Orthidox Church and Whole Food Plant-Based guidelines? They overlap quite a bit. Clearly, the fasting guidelines don't employ any processed foods but are they SOS-free? Don't know. Perhaps the ebook below explains (I haven't read it yet). [SOS-Free means free of salt, oil and sugar]

Book: (2020) Unnoticed Wisdom of Ancient Civilizations: Ethiopian's Genius Eating Pattern by Dara Babatunde.

(2021) Dietary guidelines by Govt of Ethiopia endorse 100% vegan food plates for those who are doing "continuous fasting":

How old is Ethiopian Orthodox Church? The Wikipedia article explains:

Excerpts from Fasting and abstinence in the Ethiopian Orthodox Tewahedo Church (Wikipedia):

Thus we have a tradition of veganism (with simple food plates from unprocessed plant foods) for hundreds of days annually going back at least 1,700 years in Ethiopia! I wonder if some percentage (maybe 0.1% of this population) adopted fasting for the entire year? I wonder if anybody has studied this population group just like we have studied the Seventh Day Adventists via so many Adventist Health Studies in detail.