Let me tell you how my journey to paleo began. As an obese former soccer player I got invited to play a friendly game after work. Hadn't played in years. Tripped, fell, and broke my collar bone. In six places. Had to have a titanium rod put in the shoulder to hold it together. $20,000 surgery. And I didn't fall hard, mind you. Found out I had osteporosis as a 36-year-old. As bad as any little old SAD grandmother.
Wondered how this could happen eating all those healthy oils like safflower, walnut, and grapeseed oil and eating healthy meats like chicken (and minimal bad red meats like beef) wrapped in healthy corn and flour tortillas. Ultimately, my experiments led to greatly higher animal fats, coconut milk, and the like. I lost weight and became strong and felt great.
Now that I eat beef and fry my salmon in bacon fat with butter on top I play soccer four nights a week, goalie, where I throw myself around in ridiculous ways. And I'm not even sore the next day (unless I get asked to sub and play three games in a row like last Friday night).
In short, I'm not buying it. PUFAs and MUFAs and/or grains gave me osteoporosis. There are other possible variables, too. But it wasn't saturated fats that did it because I wasn't eating them.