SR is right ... one or two days with low calories and you would likely feel a bit drained but be okay ... 2 weeks right before your race and you may very well be in trouble.

You are by now well trained so why not back off on the running a bit and let your stomach calm ... while adding in easy calories ... ensure (canned drink with lots of cals), PB, small bowl of buttered noodles. At this point don't worry too much about what you eat, just think of what sounds at all good and try that ...

when I feel no interest in food I have this thin german toast (110cal a slice but not high volume and smear it with PB or butter ... easy to eat and high cal for low volume).

600 calories? Yikes! I'm no expert, but that's pretty low. PLease eat more. Food is the best source of energy for our bodies.

I may get flamed, but here are my two cents.

I say if you are hungry, eat..if not, don't.

Barring any circumstances you aren't telling us about (illness, pre-existing medical conditions, etc), your body is your best gauge. Again, if you are purposely not eating to keep weight down or for some other reason, or if you don't have time to eat, thats different.

But, if you are genuniely not hungry, don't force it. I think that would be the worst thing to do. In the same vein, however, it seems as if your body is out of wack. If this is the case, i would strongly recommend NOT running the marathon. Life gets in the way of stuff sometimes. You just have to go with it. Theres nothing shameful about putting running on the backburner for a while. I'm sure this isnt what you want to hear, but its what I would do, and I speak from a ton of experience. Going into a race not feeling like yourself is never fun.

Two weeks is a long time away. I would just eat if you feel like it and not eat if you don't. Make sure you make healthy choices, though. Don't bother eating more calories than you burn in a given day on purpose.

I usually try to lose some weight three to one week before the marathon. feeling bad during one run does not mean anything, really. Remember three days before the marathon is when it really becomes significant.