There are several meal replacement programs sold in the dieting community. I was on one for three months where I could choose to consume zero solid food and get all my nutrition from powdered soups and shakes; the US equivalent seems to be Medifast, though that includes a single food meal daily. It was not a healthy plan, but my energy levels were great and I lost a significant amount of weight in that time (45 pounds or so). The composition was designed to induce and keep participants in ketosis, but I don't see why a little more carbohydrate couldn't be added to avoid this.