I remember trying to calculate it a couple times, by mass.
One berry equals about a centimeter or two of a single branch, not in wood but in foliage, a single strand.
The energy isn't that much of an issue because juniper berries are pretty resinous and super high fiber, but the proteins that go into it are depleting the rest of the plant a little..
If the juniper has no traces of Sabina in it, then you could use the berries to spice up some alcoholic spirits or spice up a stew. Rabbit or deer stew from European recipes traditionally contain a couple juniperus communis berries.
If they contain sabina genetics, they're toxic.