Lembas For Mordor

"Simply Walking into Mordor: How Much Lembas Would The Fellowship Need?"

The full analysis is in the paper (PDF).  Their conclusion:

Using hourly metabolic rates for the species, this is approximately 304 pieces for the hobbits, 214 for the ‘men’, 99 for Gimli and 60 for Legolas, assuming that they only eat their daily required amounts.