Current bare starting health is 10.5k (just checked it on live).
Starting health post CP system is supposedly 16k.
As I read it, we're losing mitigation passives in CP, to the tune of a removal of the direct/dot and hardy/elemental CPs. Unsure if we're losing armor focus alike, but for now we'll let that one hang (if someone knows how they're handling that in the red tree please tell me).
This means that, borrowing from a very experienced player's mitigation calculation, we're losing two sources of "effective hp", but gaining another (Higher base hp).
Now the math.
Say you have a character (let's use mine for simplicity) that has the following stats.
HP: 10.5k
Dot/Direct stars 19% mitigation
Elemental/physical stars 11%
Armor: 16.5k (after stars and dk passives)
and compare it to a character post changes who has
HP: 16k
Armor 16.5k
And compare their effective resistance to damage
Live (no food): 10.5 / ((.81)(.89)(.75)) = 10.5/.541 (rounded)
Effective HP: 19.4k HP
CP2.0: 16k/ (.75) 16k/.75
Effective HP: 21.3k HP
Live (food): 17.5/.541
Effective HP: 32.34k HP
CP 2.0: 21.4/.75
Effective HP: 28.53k HP
So, an interesting thing; For a lot of builds, they'll be a bit weaker with stat food than pre update. I saw a lot of people saying they could run stat and regen food, and I'd advise against it. Without access to the PTS, I'd also greatly appreciate it if someone could tell me how many HP points/cp you can squeeze out of the passive red tree.
Food for thought.