Your health has much to do with your genes.  My uncle was 97 when he died.  He ate bacon,  saugage, scrapple and eggs for breakfast.  He never ate fruit or vegetables.  He ate ice cream every night for a snack.  My mother is 92 and eats everything and she is very healthly.  My father's first cousins were 97 and 100 years of age when they died.  My grandparents on both sides were in their 90's when they died.  They ate everything.  

True. I have the identically same experiences in my family. They ate everything! However, they grew up in a different time, when foods where prepared at home. I'm not sure we will live as long, eating these foods of which we don't even know for sure what's in them.

I think that the paleo-evolutionists are silly. People haven't changed, but our lifestyles have. Grains are wonderful but as far as our modern lifestyle goes, the two main issues are that refined grains are nutritionally inferior and as lifestyles shift away from manual labor, even in recreation, we aren't expending the amount of energy needed for our bodies to use grains properly. Under different and certain conditions grains are good, but there is no denying their contribution to diabetes and other disorders. The number of people with celiac disease is growing exponentially.

Our soil is different, growing practices are different, our seeds are different, too. I don't know if that contributes to the problem but it is something to consider.

Overall, eating primal/paleo can be adapted for Lent and done in a spirit of penance, a vegetable stock, made into a simple monastery soup, for example, or eggs which are simple, inexpensive and versatile. Maybe people are not able to cook as well, and these simple nutritious things have been cast aside for boxed mac and cheese during Lent? But really, which makes better use of God's gifts in the harvest? Which is less wasteful?

Speaking of waste, the primal diet is much better in terms of using everything and letting little go to waste, even in terms of packaging. Lard and other healthy fats can be used, how many people actually save their bacon grease? Yet, is it not wasteful to throw it out? The traditional diets also make use of offal and bones, and other parts of the animal instead of letting them go to waste.

On a side note, people who eat this way are more likely to buy direct from a small scale farmer, which promotes an economy which is more in line with Catholic thought on economics.