Supporting husband

My husband was diagnosed with tonsil cancer with lymph node involvement in January and finished a 6 week course of RT and 2 cycles of chemo at the end of March.  He needed an NG tube from the end of week 3.  He showed marked improvement about 3-4 weeks post treatment and had his NG tube removed at 6 weeks as he was able to eat and wanted it removed.  However, although he is able to swallow without difficulty, he is finding it very difficult to eat much.  He has very little taste and feels full after eating only a little.  Also he says that he just has no desire to eat.  He is having some of the drink supplements, but I am worried that he is not getting enough calories.  I keep trying different things to tempt him, but to no avail.