Hi, as much as what, as much as he or she used to? Or as much as some otheer 16-month-old that you know? Babies do sometimes go through a period of time where they seem not to eat a lot, but if the baby is not hungry, he or she is not hungry. I remember a neighbor of mine, an older lady who used to come over two times a week to help me for a couple of hours, muttering under her breath about my son, "Not eating enough to keep a gnat alive." But my son wasn't hungry and he wasn't thin. If your doctor assesses that your baby is losing weight, then be concerned. But if not, try to relax.