I suffer a similar problem with eating and subsequent weight loss. I was recommended (by dietition) Scandishake sachets. Each sachet (approximately a mugful) contains 600 calories I believe. I take 3 per day and they come in a variety of flavours.
While this number on its own is, again I believe, insufficient for a recommended daily food calorie intake, I find them very easy to consume especially when chilled. I obtain mine on prescription. I hope this helps. Fridge