MrsTP and Pan I couldn't agree more.
Not just the innocent, but even murderers should be fed properly. How could we possibly be part of a society that locks people up for the rest of their life and doesn't treat them decently?
I heard Claudia Sturt (a prison governor) give a very moving address about the reality of prison life: of sleeping with your face 15 inches away from your open toilet that you can't clean because you are not trusted with bleach (unless you decide to use your toothbrush, or your key fob), of never getting away from the smell of faeces, of lying awake at night hearing people crying and self harming. Being in prison is sufficient punishment for any crime; we do not have to make people ill too through poor nutrition.
The lifer I visit tells me how her fellow inmates are regularly trying to kill themselves. Of how she has some friends whose cells she is nervous to visit as there is sometimes the results of a suicide attempt (successful or failed) And of how she tries to stay out of the hospital wing as that is where it is worst (so she never admits to being ill, even seriously ill). This is so wrong and all starts with the kind of knee jerk response that prisoners have forfeited all their human rights.
Oh, and because only the hardest criminals work in the prison kitchens (it is too dangerous unless you have status in the prison), the food can often be contaminated. You would not wish that on anyone, 5 choices or otherwise.
On the cost side, let's lock up fewer people and for less time. Let's concentrate more on meaningful justice and on rehabilitation and education. It will be cheaper and more effective in the long run, even with decent food.