Hmmm...  Your question "why would you have cut your protein intake before the Fontana study when you were out of the loop?" can be interpreted in either of two ways. The first, less plausible, is as a hypothetical. I.e. what would have caused you to cut protein, whether you did or not?   I suspect you are asking when actually DID I cut protein, and why. At least that is how I'll interprete your question.   First off, I went vegan in 2004, meaning I was inclined towards less protein, and less highly-assimilatable protein, since around then. The reason for the switch from omnivore to vegetarian (circa 2002) and then from vegetarian to vegan (in 2004) was mostly ethical. I continued to eat relatively higher protein than I do now during those early vegan years, via supplementing with plant-based protein isolates (pea, rice, soy & hemp protein) as mentioned above.   The best data I have from that era, available at my VERY OLD personal website here:   is that in early 2005, I was eating a diet of around 2000 kcal/day with a macronutrient ratio of 20:53:27 P:C:F. This is lower protein (and fat) than the Zone-ish macro ratios that were popular back then (30:40:40), but not as low as the 12-14% protein that I (and I believe you) eat these days, as a result of insights about the downsides of extra protein.   Exactly when I dropped lower than 20% protein is hard to say. In email to Luigi for a human CR study visit to WUSTL in 2008, I was still eating that same diet above with 20% protein. So it was sometime between 2008 and 2012, at which point I have definitive evidence (via CRON-O-Meter) that I was eating 14% protein (around 14:56:30 PCF).   Subsequent to that, in early 2013, I shifted from around 14:56:30 PCF to 13:71:16 PCF - i.e. the high-carb, low-fat, mostly raw vegan diet that I eat today.   Finally, it was definitely NOT the China Study that motivated any of my dietary changes, although I admire the work of Collin Campbell, despite the way he and the other four "horseman of the vegan apocalypse" (i.e. John McDougall, Neal Bernard, Dean Ornish, Michael Greger) tend to oversell the benefits of a low-protein, low-fat, strictly plant-based diet. ;-)   Finally, thanks for prompting me to do this bit of "diet archeology". It's nice to have a better picture of one's dietary evolution over the years.   --Dean