Chetan,
I felt so rough with my tongue surgery. I know I lost weight, after each surgery, the excision biopsy, the clean margins, the new excision--to take wider margins, being the worst. I ended up anemic.
I am not a vegetarian, but ate almost no meat, so it was easier for it to happen I guess. (with use of iron pills & careful dietary choices, I was able to raise my hemoglobin and hematocrit to normal levels post treatment) BUT, you have to be careful because you definitely want to have as few pre-existing problems (i.e. low weight, blood counts) going into treatment. Most of us get mouth sores that slow us down, mine not being nearly as bad as some.

Re: chemo. I did not like it, but I had it 6 times, once a week over the 6 weeks. I did not have nausea because Zofran took care of it, but I just felt lousy for 3 days afterwards. It was explained to me that it was a boost to the radiation, so it I did not need a heavier dose of radiation. To me the radiation was not bad until the last few days and afterwards. I do not know about have two lymph nodes vs one and having chemo. The chemo was added in for me because of the extra capsular extension, which as I said microscopic. I would say you might be border line.

I'm with Christine that you need to consume more, and if your tongue is still really too bothersome for solids, drink more of those Ensures, or Boosts, or Carnations. Keep working at it and it will get better.
Anne