Source? I have not heard of this. Our nurse emphasized that while a child is on formula, that's really all they consume for both nutrition and hydration, so it needs to be balanced per manufacturer guidelines. They don't have a way to signal "I thirsty" or "My tiny stomach is full of watery stuff but my blood sugar is still low". Their digestive and urinary systems are pretty amazing, but habitually using too much or too little (wrong scoop, wrong ratio, packing it dense) can be unhealthy.
I don't really have a source, but it's common with protein powders.
They'll list 28 grams as a serving size with a scoop that has a line in it about 3/4 of the way up that represents 28 grams. Technically not misleading, but it's absolutely reasonable that people would assume 1 scoop = 1 serving size. The end result is that people go through more product.
If you watch professional bodybuilders who have to be very exacting about their intake, you'll see them tell you to always measure on the scale because you can't trust the scoop.
That and a few cheap plastic containers with lids. Measure out a handful of those. Keep at least one always ready for those times when the baby's very, um, demanding (loud).
