Carol,
I think like everybody says each person is different. My mom went through 2 surgeries she started at around 170 lbs (shes 5'8) with the first surgery in April 2003 after that surgery she went down to about 150 lbs. Since they removed a large portion of her tongue eating was very difficult. Then when she had her surgery again in December 2003 she was already back up to about 170 lbs and she lost about 10 lbs after surgery but she tried to eat everything she could before radiation and chemo because she knew she would lose quite a bit of weight. She went down to 135 lbs after radiation now 4 months out she has stayed at 135 lbs. Even though she eats quite a bit she has had a very difficult time gaining any weight back. She doesn't look unhealthy but she did loose a lot of muscle so she has lots of loose skin which she has been exercising to try to tone a little.
My mom still drinks one of those 1300 calorie shakes a day and it has had no effect on her weight.
Take Care,
Dani