What is "Mateh Lechem"?
Rashi: The support of bread. Radak - it supports man, just like a Mateh (staff) supports a weak person. Also in the Torah it says "b'Shivri Lachem Mateh Lechem" (Vayikra 26:26).
What is "bi'D'agah"?
Rashi: They worry lest their bread be finished.
Radak: They worry lest they lack bread and water.
Why does it say that they will eat by weight and amidst worry?
Radak: This explains why Hashem commanded Yechezkel to eat by weight and drink in measure - it is a sign for Bnei Yisrael.
Malbim: Hashem told Yechezkel to eat for 390 days by weight, for in Yerushalayim they will eat by weight and amidst worry, for they know that the bread will finish afterwards.
What is "Shimamon"?
Radak: It is frenzy.
