uLundhu vs muttai---one more example of Brahminical contradiction

"Traditionally made during death ceremonies, but nowadays in most festivals in Tamil Nadu, a specific type of vadai called uddina vada(uLundhu Vadai) is served. This is made of Urad Dal or ulundhu, which has one of the highest protein contents among all dals (100 gms of uLundhu has 24.0 gms of protein), and is thus one of the main protein sources of the meal. Historians today believe that this food item is proof of a certain change in the habits of Brahmins which took place around 500BC. The advent of Jainism which emphasised vegetarianism, is supposed to have caused this change in food habits. The Brahmins had to compensate for the loss of proteins from meat by eating uLundhu."

My friend send me this interesting question from an IITM open quiz. My mother says that Yogis, Siddhars and Gyanis are prohibited from eating uLundhu. They eat aval and pori instead. Further she quotes Balakumaran. And to add to this my Yoga teacher asks me to not eat Vadai if I care to reduce my weight. One Vadai is equivaent to 2 eggs he claims.

Now assuming that all this is true, what on earth are the Brahmins(and other junta too) of today doing eating, Idly and Dosai (both contain a lot of uLunthu) on Viratham(Vrath)days? Devarukke telusu..