How far can you go in Shabbos leniency in order to prepare food?

Question

I am referring to situations in which it is very likely that there will not be any food unless Shabbos leniencies are exploited. For example, if literally all my food is all in the fridge, but I know I left the light in--can I open it, if it's the only way I will eat Shabbos? Or if someone deliberately misused the blech, and all of the food we have is dependent on profiting from their melacha, may we still eat? Or if my [only] food is wrapped in something that would require extensive work to open, may I open it in order to eat?

The focus of my question is not on whether or how such a thing could possibly occur, but on where having no food at all on Shabbos would fall on the scale of illness and other extenuating circumstances that could lead to a loosening of (particularly rabbinical) strictures.

I imagine a situation in which there is no immediate threat to life or health, and in which--for the sake of interest--there is also no risk of not completing the positive mitzvot. In other words, one has enough wine for 1 kiddush, and enough for 1 kezayis (kebeitza?) of bread x 3 meals per person. But literally nothing else.

Answer 1

Very good question. For a little child RMA OC 328, 17 told about melachot for little children meal preparation and allows only shevut of amira lenochri. Even no active derabanan chillul, even by the person who is chole sheen bo Saccana when there is no sakkanat evar. Roughly the Rosh is the stringent opinion and for the Rambam, Machloket Tur and Bet Yosef if he is really lenient.

See this stuff of SA (op. cit.)

וְיֵשׁ אוֹמְרִים שֶׁאִם אֵין בּוֹ סַכָּנַת אֵבֶר עוֹשִׂין בְּשִׁנּוּי: {היינו שעושין בשינוי וכו' ודוק בפוסקים ותמצא שהוא מגדולי הפוסקים ודברי הב"ח צ"ע: מגן אברהם} ‏

Shulchan Aruch (and Magen Avraham end of sk 12) ( thanks to @Double AA) allows Shvut deshvut by Israel itself when there is a bit of illness: To make a isur deorayita with shinuy:

The leniency is valuable only if there is a bit of ilness, not only disagrement.

וכמ"ש סימן ש"ז ס"ה שבות דשבות שרי במקצת חולי ומיחוש בעלמא אפילו ע"י עכו"ם אסור וכמ"ש ס"א ועמ"ש סי' תצ"ו:‏

Magid Mishne Shabbat 6, 9 in name of Raavad which is the source of this text.

Thus, To make a mel'acha derabanan with shinuy, for a bit of illness is allowed by SA. But e. g. to open the door of the fridge with the foot, (turn on the light is a problem keein deorayta even If he doesn't need it (מלאכה שאינה צריכה לגופה) ) seems not possible.

Or if my [only] food is wrapped in something that would require extensive work to open, may I open it in order to eat?

It is always the possibility to destroy entirely the package.

Answer 2

Not all sages say that the Shabbat is a feast.

Rabbi Yosé ben Zimra went so far as to declare that Jews who fasted on Shabbat were assured of the cancellation of any negative decrees that had been issued against them by the heavenly court.(Brachot 31b)

Some of the sages say that the reason we gather extra manna before shabbat is because we should eat Enough before shabbat and that the day of shabbat is more spiritual.

(This is a view from some sages,dont downvote it because I give light to a view in the Talmud)

http://people.ucalgary.ca/~elsegal/Shokel/021031_SabbathFast.html