Genesis 2:16

And the Lord God commanded Adam, saying, Of every tree of the garden eating thou mayest eat.

מכל עץ הגן, depending on which tree’s fruit was in season. Each season required nutrients appropriate to the prevailing climate, and the fruit ripening during the various seasons would provide man with these nutrients. The prophet Ezekiel 47,12 expresses this thought in the words לחדשיו יבכר “in its appropriate month it will yield new fruit.”

ויצו ה' אלוקים, the commandment mentioned here may either apply only to the specific fruit Adam was not to eat, or it is a dual commandment, the positive commandment being to eat the other fruit in order to keep healthy, and to shun the fruit of the tree of knowledge precisely for the same reason, as it would prove extremely harmful. G’d emphasised the importance of eating in order to keep alive and healthy by repeating and saying אכול תאכל, meaning: “be sure to eat!” Such repetitions are always used in the Torah when the Torah wants to underscore a point. A well known example is Deuteronomy 11,22 שמור תשמרון, where the Jewish people are warned insistently not to become guilty of violating the preceding commandments by ignoring them. A similar repetition is found a few verses earlier (11,13) when the performance is urged with the words שמוע תשמעו, “be sure to listen (and carry out).”
Our sages (Bereshit Rabbah 15,6) claim that Adam had been commanded 6 commandments. This verse was written where it was to illustrate that chronologically, this was immediately after he had received these commandments.
They said furthermore that the word ויצו referred to the prohibition to commit idolatry. This word has again been used to describe such a prohibition in Hoseah 5,11 כי הואיל הלך אחרי צו. “because he followed the path of idolatry.” The word Hashem in that verse refers to the law prohibiting cursing G’d by invoking His name. (compare Leviticus 24,16) The word אלוקים in the same verse refers to the need to deal with offenders of the law by legal means (compare Exodus 22,27) The words על האדם in our verse refer to the prohibition to shed human blood, something spelled out in greater detail in Genesis 9,6. The word לאמור alludes to illicit sexual relations including incest. The prophet Jeremiah 3,1 refers to widespread non-observance of this legislation even among the Jewish people. The seventh law was spelled out in detail, i.e. not to eat flesh while the animal from which it stems is still alive. This law was not applicable before Noach had thanked G’d for his deliverance, as all flesh had been forbidden as food until that time.