I'm also drinking ensure, but sometimes I feel not so well, I suppose it causes toxicosis.
I would drink pediasure with my 1 st and 2nd, with 3rd and 4th I drank muscle milk, now I'm doing carnation instant breakfast. I think it's OK as long as you're not using it as a meal substitution. If you're overweight dr may be concerned that is liquid calories which puts on more weight but it doesn't effect health