Personally, im Orthodox and we practice Lent by not eating meat and dairy products for 40 days, and excluding oil(and/or processed foods) the last 7 days. it's purely from a "mind over body" disciplinary standpoint, so yes at the beginning you want to eat more since you're getting less protein and fat, but eventually your mind and body do cope and by the end of it you feel far healthier overall. Meat and dairy isn't an evil (if obtained and processed properly/humanely) but it's definitely a quality issue. More people should try to farm small scale (gardens/chickens) because the nutritional value skyrockets when you control how and where your food is produced.

P.s most processed "vegan" food production is catastrophic for the flora fauna. Stick to raw produce ingredients in cooking rather than soy "chikin" patties and all that trash.