If you have meat with bones, don't throw away the bones. Make soup. In this way you can stretch a meal into two meals. You may be able to save money by learning to cut up a whole chicken rather than buying pieces.
If your situation is truly dire, you may qualify for a food pantry.
Also, there are edible wild plants to harvest, even in the city. I regularly forage for mustard greens and plantain (Plantago elongata, not the banana). Grows as weeds in open spaces. I've also eaten chickweed, stinging nettle (favorite!!), bedstraw and miners lettuce. Dang chickweed grows in my garden instead of the stuff my black thumb planted. May as well eat it. There are others I have not tried, like dandelion. A bag of wild greens foraged for free can take the place of a $3 bunch of swiss chard at the grocery store. I recommend the book Edible and Medicinal Plants of the West for good pictures. You may have stuff in your area I don't have in arid So Cal, possibly better stuff.
Another thing you can do, if you have time to take a walk, is find some alleys or neighborhoods where people's fruit trees grow over the fence. Any fruit that grows over the fence is fair game, it's not stealing. I've harvested plums, apples, apricots, cherimoya, sapote, loquats and pecans. If your neighbors have fruit trees, you can also ask if they'd mind if you harvest some. Sometimes people are really super happy to give their fruit away because they have too much and don't know what to do with it! If you have fruit trees, you can trade or even sell your produce. I made about $50 selling avocados on the honor system in my driveway. I just put out a box of avocados, a sign that said 50 cents each and a box with a slot to drop the money. People were honest!
Female, 5'3", 50, Starting weight: 163lbs. Current weight: 135 (more or less).
I can squat 187.5lbs, press 75lbs and deadlift 200lbs