Comment by rpozarickij

Limiting animal fats (which are mostly saturated fats) has a very noticeable and measurable effect on how I'm feeling and doing overall. Primarily using olive/avocado oil and nuts/seeds as my fat sources significantly improved my energy levels, mental clarity, sleep, and stress/HRV (as measured by my Garmin watch). I've noticed this so many times that I don't think this is a placebo. I haven't checked any specific blood markers that might be affected by dietary fats though.

Saturated fats _are_ essential for humans but you should be getting enough of them from non-animal sources.

YMMV