(10) When you have eaten your fill, give thanks to the Eternal your God for the good land which God has given you.
וברכת [את] ה' [אלהיך] על הארץ הטובה. מצוה. ומכאן תקנו שלש ברכות שבברכת המזון. ואכלת א' ושבעת ב' וברכת ג', שמברך על אכילתו זהו ברכת הזן, על הארץ זהו ברכת הארץ נודה לך, הטובה אשר נתן לך, זהו בונה ירושלים דכתי' ההר הטוב הזה והלבנון.
וברכת המוציא מק"ו דהשתא כשהוא שבע ונפשו קצה באוכל צריך לברך. כשהוא רעב והוא תאב ושמח על האוכל לא כל שכן?
מעת' אין לירא אלא שתבעט מתוך שיפוע הטובה, ולכך אני מזהירך שלא תשכח את הק' שעשה לך כל הטובה הזאת. ואפי' כשיצערך לענותך, נתכווין לטובתך להטיבך באחריתך:
A commandment. And from here they established the three blessings of Birkat HaMazon. 1. "And you shall eat..." 2. "And you shall be satisfied..." 3. "And you shall give thanks..."
When we recite a blessing for food, that is Birkat HaZan (#1). For the land, that is Birkat HaAretz Nodeh Lecha (#2). "The good that God has given you is Boneh Yerushalayim (#3), as it is written: This good mountain and the Levanon.
And Birkat HaMotzi [is derived] from a Kal Ve'Chomer argument: Now when one is satisfied and their gullet is filled with food, one needs to give thanks. When one is hungry, and has an appetite, and is joyful for the food, is it not more so [appropriate to give thanks]?
From here, the only concern is that one expresses themself because of the flow the goodness, and thus I warn you not to forget God who does all of this good. And even when God is causing suffering and affliction, we should focus on God's goodness that God bestows upon you all along. (This is based on the Talmud Brachot 48b)
וברכת את ה׳ אלקיך לרבות בעל הבית.
...The word את in the line: את ה׳ אלוקיך; this includes the owner of the house [in which you have consumed this food, i.e. your host.]
לברך את השם אחר אכילת המזון - לברך את השם יתברך אחר שיאכל האדם וישבע מלחם או משבעת המינים הנזכרים בכתוב (דברים ח ח), כשהוא זן מהם
ולחם סתם נקרא פת העשויה מחטה ושעורה, ובכלל החטה הכסמת, ובכלל השעורה שבלת שועל ושיפון,
ועל כלל שבעת המינין הזנין נאמר (שם י) ואכלת ושבעת וברכת את יי אלהיך על הארץ הטובה וגו'.
וזאת השביעה אינה שוה בכל אדם, אלא כל אדם יודע שביעתו, וידענו שעור שביעת הצדיק, שהוא באכלו לשבע נפשו, ארצה לומר, כדי מחיתו לבד...
To bless God after eating food: To bless God after one eats and is satiated from bread or from the seven types [of food] that are mentioned in the verse (Deuteronomy 8:8) when they are nourished by them.
And a loaf made from wheat or barley is called lechem stam ("just bread"); and included in wheat is spelt, and included in barley is oats and rye. [These are called the Five Grains.]
And about the seven types that nourish is it stated (Deuteronomy 8:10), "And you shall eat and be satiated, and you shall bless the Eternal, your God, for the good land, etc."
And this satiation is not the same with very person, but rather every person knows their [own] satiation. And we know the measurement of the satiation of a righteous person is to satiate himself, [by which] I mean to say, only for his sustenance.
Here is a hint that one should not to eat like a glutton, but to eat in order to live. We learned this first when the Torah describes the amount that Joseph sold to the brothers. The amount is described as שבר רעבון, i.e. enough grain to still the hunger (Genesis 42,19). This is the meaning of the words לא במסכנות. On the one hand one must be careful not to suffer from under-nourishment; on the other hand one must not eat as a matter of indulgence. This is why the Torah demands that we give thanks to God as soon as we have eaten enough to feel sated, (8,10). We should train ourselves to be satisfied with what God has granted us.