Ensure for weight gain

So I've gained a total of a steady 5 lbs this pregnancy but it fluctuates between 5-7 when I'm at the doctor due to time of day, anywho my baby's stomach is measuring small and doc recommended I drink ensure for weight gain and to get more nutrients and protein to the baby. Has anyone tried it or them? What's the best flavors? I hate shakes in general so hopefully I don't waste them.