Examine.com - A great quick meta-reference for all supplements. They do a great job organizing the relevant research.
Ogrestrength Pharmacology - Blog run by a friend looking in depth at some supplements.
Chaos and Pain - NSFW, a nice site for powerlifting with some strong opinions and a strong author. Bulgarian/Old school style focus for the training.
Suppversity - great in depth fitness/diet/supplement articles written by a physicist
Ergo-log - great blurbs on research on fitness related topics
Longecity - Great for nootropic and general health research
Mark’s Daily Apple - An awesome site for the science on specific food choices. Specifically great for learning about what healthy fats are and what the benefits are.