Cezar

Weight loss varies by individual. Doctors don't like to see any as Christine noted. If burping up Ensure makes him nauseous, I'm not sure what VHC would do. Usually you can get a can for free to try out at the hospital.
Another option is to use a blender (Vitamix is the very best but expensive although they have a medical discount program for a reconditioned one for $300) to mix up high calorie shakes for your Dad. You can put in things he likes the taste of, add some flax seed oil and you will have a healthy supplement to put some more calories on. Ensure Plus has more calories than regular ensure and that's what I lived on the last three weeks of radiation and chemo.
Charm