Strict Fasting Rules Prohibit Animal Products, Including Salo
According to the provided materials, traditional fasting rules require a strict abstinence from animal products, including salo. During strict fasting periods, only plant-based food is allowed, and products obtained from animals (including meat, fish, dairy products, and even oils) are not permitted. This regulation is reflected in the prescriptions, which emphasize that food should not cause undue heaviness or contribute to indulgences in carnal pleasures.
For example, one source states:
"Thus, the fast during Holy Forty is not only about abstaining from meat and cheese, but even from fish and oil; it involves a dry diet (that is, without oil), and during the first week, the first two days are prescribed to be spent without food at all. The Church Fathers strictly censured those who consumed even fasting-approved but refined food during the fast." (source: link txt)
The principle of abstaining from meat is also highlighted:
"We refrain from consuming meat not because we regard it as unclean, but because it produces a particular heaviness throughout our system, hindering our spiritual progress." (source: link txt)
Since salo is an animal product (in this case, pig fat), its consumption contradicts these strict fasting rules. Consequently, from the perspective of the religious traditions described in the cited materials, salo should not be consumed during the fast.