This is an important consideration. The target audience of Soylent likely has some wild variation in desired caloric intake, perhaps 4-6x between people who want to drop some pounds and people who lift as a hobby.
Yeah. The creator of Soylent makes a point of saying that it should be tuned for the person using it. Hopefully in the long-term they'll offer versions with varying calorie content. Alternatively, they could offer a two-component system with nutrients and minimal calories in one and pure calories in the other, to make it easy to tune that one variable for your target calorie consumption.