Sorry about this, real simple newbie stuff but I have spent the last hour browsing manuals and strategy guides and can't find the answer - it must be somewhere obvious that I'm not looking.
I think I understand this screen (but not the next one):
Health:
I'm on Noble, so I get 2 free health, plus 3 from resources = 5
My pop is 7, so that's -2 health, which means 2 food subtracted from whatever I am producing.
Happiness:
I get 4 free, plus 1 each for the Palace and a resource =6
7 pop gives -7.
So that's -1 happy, = 1 angry citizen
Food production:
Of my 7 citizens, 5 are working water tiles = 10 food
'Free' from my city tile = 2 food
Health penalty = -2 food
Total = 10
Pop = 7, so I require 14, so that's -4 starvation
Settler production:
I thought it worked like this: During settler production, all food surplus is diverted to the settler, and converted into equivalent hammers.
I have no surplus food, 1 free hammer from my city tile plus 1 from my 1 unassigned citizen = 2, as shown in the production bar.
BUT now, I take my unassigned citizen, and assign him to another water tile:
The starvation works just like I expect - 6 citizens give 12 food, plus 2 from the city tile, -2 from health = total food 12. Pop 7 means starvation of -2.
But the settler production doesn't work - there's 3 extra food appeared from somewhere, to give me the 1 food shown in the settler production bar.
This 'extra' 3 applies if I reassign the citizens to better food producing squares. I won't waste space with another screenshot, but trust me:
If I have them on tiles worth 21 food
Plus 2 from the city tile gives 23.
Less 2 for health gives 21.
Less 14 for pop, leaves 7.
But the settler production bar shows 10 from food (+whatever actual hammers there are on the worked tiles).
Even if I am wrong about the way health subtraction works, it still doesn't work out sensibly.
I must be missing something obvious - help.
I think I understand this screen (but not the next one):
Health:
I'm on Noble, so I get 2 free health, plus 3 from resources = 5
My pop is 7, so that's -2 health, which means 2 food subtracted from whatever I am producing.
Happiness:
I get 4 free, plus 1 each for the Palace and a resource =6
7 pop gives -7.
So that's -1 happy, = 1 angry citizen
Food production:
Of my 7 citizens, 5 are working water tiles = 10 food
'Free' from my city tile = 2 food
Health penalty = -2 food
Total = 10
Pop = 7, so I require 14, so that's -4 starvation
Settler production:
I thought it worked like this: During settler production, all food surplus is diverted to the settler, and converted into equivalent hammers.
I have no surplus food, 1 free hammer from my city tile plus 1 from my 1 unassigned citizen = 2, as shown in the production bar.
BUT now, I take my unassigned citizen, and assign him to another water tile:
The starvation works just like I expect - 6 citizens give 12 food, plus 2 from the city tile, -2 from health = total food 12. Pop 7 means starvation of -2.
But the settler production doesn't work - there's 3 extra food appeared from somewhere, to give me the 1 food shown in the settler production bar.
This 'extra' 3 applies if I reassign the citizens to better food producing squares. I won't waste space with another screenshot, but trust me:
If I have them on tiles worth 21 food
Plus 2 from the city tile gives 23.
Less 2 for health gives 21.
Less 14 for pop, leaves 7.
But the settler production bar shows 10 from food (+whatever actual hammers there are on the worked tiles).
Even if I am wrong about the way health subtraction works, it still doesn't work out sensibly.
I must be missing something obvious - help.
)) and then there you go. A good ol' screenshot. 
. 
from population you need 16 
to avoid starvation. Thus in the first / second screenshot you produce 12 / 14 
for the 1 extra 
If you can't fix it, feature it...
