Didn't The Israelites Pre-Plan When They Left Egypt?
The Israelites didn't leave Egypt unprepared. They left hurriedly, but not without instructions by God, through Moses (Exodus 12:1–28). The people had eaten a Passover supper the night before they left Egypt. Exodus 12:32 and 38 both testify that the Israelites did indeed take great flocks and herds with them when they left Egypt. It is also mentioned in this passage that they took balls of unleavened bread dough, and may have additionally taken food from the Egyptians when they were leaving (Exodus 12:36). So the Israelites definitely did not leave hungry or without provisions.
Seventy-Five Days Later Though, They Appear To Be Starving?
However we read in Exodus 16:1–3, that it was the fifteenth day of the second month after they departed from the land of Egypt, when the whole congregation of the children of Israel complained against Moses and Aaron in the wilderness. They were so hungry that they were dreaming of the "good old days" of slavery in Egypt when they supposedly had full stomachs. In other words, 75 days after they left Egypt they began to complain about being intensely hungry. How could this be?
The obvious answer is that a lot can change in 75 days, especially with a lot of hungry mouths!1 The second obvious answer is that the Israelites were merely grumbling but not really starving (think of a three-year-old child saying he is starving because he wants some chocolate to eat all the while neglecting his dinner). Let's evaluate the options in more detail though.