All depends, many people on weight loss diets chop the amount of calories drastically, and also depend on what you want to add to your 2 cans of soup a day…
Campbells split pea with ham and bacon :
Amount Per Serving (serving size) = 1/2 cup
Total Fat 3.5g
Total Carb. 27g
Dietary Fiber 5g
there being 2 servings per can of soup - makes it 720 calories per day, 7 grams of fat, 54 grams of carbs, 10 grams of fiber, 8 grams of sugars and 20 grams of protein.
I have seen people on an 800 cal a day diet for severe weight loss, and if you added cheap bread [packet of yeast is abotu $1US, and if you make a lavin, or sourdough starter and keep it alive, you have eternal yeast to make bread with. Flour, water and salt are all you need. Salt is very cheap per pound, water is available in your kitchen sink and flour can be very cheap if you go for generic basic white bleached flour. Add a loaf of bread a day, and the 2 cans of soup though boring would actually emulate a menu common to many eras in our history. If you wanted to add carrots, cabbage, onions and alfalfa sprouts to your diet, they are all fairly cheap as well. [alfalfa seed is available in many health food stores and that little package goes a fairly long way and can be sprouted at home dead easy.]
When I was very broke, I would make a pot of cabbage soup and that would be my food for the entire day, all 3 meals - 1 spicy italian sausage out of a package of 6, 1 onion, chopped, 2 stalks celery, chopped, 1 potato chopped, 2 cups chopped cabbage, water, tsp of generic italian herbs and a chicken bouillion cube. I kept a sourdough starter living in my fridge, and baked up a loaf a day, and made a lot of cabbage soup=)
Back in 1986 this cost me about $2 US for the day. I would also make a ramen soup - 1 packet ramen, 1 carrot, 1 celery, 1 chicken wing, seasoning packet. Also dead cheap.