They do require a slight amount of work, but not necessarily a lot. The easiest sprouts to make are lentils. The easiest way to make them is simply to soak them in a large plastic cup for 4-8 hrs, then drain and keep moist by spraying and occasionally rinsing. They can be eaten as soon as they get soft enough, though sometimes hard seeds might still exist for 8 hrs or more, which are bad for teeth. Sprouts can be allowed to grow for a couple of days.
Sprouts make a person hungry, as do other types of raw food to some extent.
So there is little danger of being undernourished on such a diet. And still, it is about impossible to put on excess fat. Eating nothing but bananas and raisins might do it, but not much else would. So persons who are concerned about fat should revert to a raw food diet. However, there is the social inconvenience that such a diet creates.