Today were getting the Quick Regeneration achievement. To unlock the perk/achievement you must overcharge your health to 200+.
It becomes simpler later in the game due to health upgrades. But you can only acquire those in the Fergus timeline, my guide works w/ either timeline. The level we are getting this on is the first one before any plot choices. It is very helpful to find the pistol silencer in the room w/ the 3 switches. Now down to the walkthrough.
Shortly after scaling the building you will proceed to raise the gates for your comrades to get through by pulling a lever. After this you slide down the chain to continue.
In this room you will see a health pack for +40. Ignore and enter the hall. A guard should enter and turn away from you. (Assuming you have the silencer) shoot him in the head and turn right, you will notice another medpack at the corner/intersection where the guard appeared, ignore that one as well.
Sneak down the hallway and you will see a rather large room w/ a staircase going down. On your left as you enter the room is a crate that when broken has +80 hp. Don't break it yet b/c it will attract guards. Wait for the guard to move out of view then proceed to stealth kill the dog w/ a headshot.
Next to the dead dog is a room w/ a commander, you will then stealth kill him and enter the room. On the table is assorted food, eat the food for a boost, then backtrack and break the box for the +80, then backtrack to get the other 2 mentioned.
If you did it right you should have the achievement!! On a side note this is my first guide and any and all feedback/comments is appreciated. Also comment if -1 so that I can improve, thank you and enjoy!